A Guide to Noise Control in Minnesota

Acoustical Properties, Measurement, Analysis, and Regulation

November 2015

Minnesota Pollution Control Agency

520 Lafayette Road North | Saint Paul, MN 55155-4194 | www.pca.state.mn.us | 651-296-6300

Toll free 800-657-3864 | TTY 651-282-5332

This report is available in alternative formats upon request, and online at www.pca.state.mn.us

Document number: p-gen6-01

Authors

Amanda Jarrett Smith, MPCA

Anne Claflin, MPCA

Melissa Kuskie, MPCA

Editing and graphic design

Tanja Michels

PST Staff

PIO Staff

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Foreword

The Minnesota Pollution Control Agency (MPCA) is empowered to enforce the State of Minnesota noise

rules. These rules and supporting acoustical information can be viewed in the document, “A Guide to

Noise Control in Minnesota.” This publication is intended to provide information on the basics of sound

and noise regulation.

Revised 2015

Contents

Foreword ...........................................................................................................................................2

Contents ............................................................................................................................................1

Introduction ......................................................................................................................................1

1. Noise rules in Minnesota ................................................................................................................2

1.1 The basics ................................................................................................................................................... 2

1.2 Noise area classifications ........................................................................................................................... 2

1.3 Common noise concerns ............................................................................................................................ 3

1.4 Regulatory agencies ................................................................................................................................... 4

2. Basics of how sound works .............................................................................................................6

2.1 Waves and sound pressure level ................................................................................................................ 6

2.2 Sound weighting networks ......................................................................................................................... 8

2.3 Human perception of sound ...................................................................................................................... 9

2.4 Using decibel measurements ................................................................................................................... 10

3. Measurement procedures ............................................................................................................ 13

3.1 General procedures .................................................................................................................................. 13

3.2 Noise Test Procedure 1: Measurement procedure for non-impulsive noise ........................................... 14

3.3 Noise Test Procedure 2: Manual measurement procedure for non-impulsive noise .............................. 14

4. Minnesota noise pollution statutes and rules ................................................................................ 18

Minn. Rules § 7030 NOISE POLLUTION CONTROL .......................................................................................... 19

Minn. Stat. § 86B WATERCRAFT OPERATION ................................................................................................. 27

Minn. Stat. § 84.8 SNOWMOBILES ................................................................................................................. 29

Minn. Stat. § 87A. SHOOTING RANGES .......................................................................................................... 31

Minn. Rules § 6102, RECREATIONAL VEHICLES .............................................................................................. 31

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Introduction

Noise is a pollutant. While its physical and emotional effects are difficult to define quantitatively, the

noise level itself can be measured.

Sound: An alteration of pressure that propagates through an elastic medium such as air and produces an

auditory sensation.

Noise: Any undesired sound.

The Minnesota Pollution Control Agency (MPCA) is empowered to enforce the State of Minnesota noise

rules (Minn. Rules Ch. 7030). Minnesota’s primary noise limits are set by “noise area classifications”

(NACs) based on the land use at the location of the person that hears the noise. They are also based on

the sound level in decibels (dBA) over ten percent (L

), or six minutes, and fifty percent (L

), or thirty

minutes, of an hour.

For residential locations (NAC 1), the limits are L

= 65 dBA and L

= 60 dBA during the daytime

(7:00 a.m. – 10:00 p.m.) and L

= 55 dBA and L

= 50 dBA during the nighttime (10:00 p.m. – 7:00 a.m.)

(Minn. R. 7030.0040). This means that during a one-hour period of monitoring, daytime noise levels

cannot exceed 65 dBA for more than 10 percent of the time (six minutes) and cannot exceed 60 dBA

more than 50 percent of the time (30 minutes).

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

1. Noise rules in Minnesota

1.1 The basics

Minnesota’s noise pollution rules are based on statistical calculations that quantify noise levels over a

one-hour monitoring period. The L

calculation is the noise level that is exceeded for 10 percent, or six

minutes, of the hour, and the L

calculation is the noise level exceeded for 50 percent, or 30 minutes, of

the hour. There is not a limit on maximum noise.

The statutory limits for a residential location are L

= 65 dBA and L

= 60 dBA during the daytime (7:00

a.m. – 10:00 p.m.) and L

= 55 dBA and L

= 50 dBA during the nighttime (10:00 p.m. – 7:00 a.m.)

(Minn. R. 7030.0040). This means that during the one-hour period of monitoring, daytime noise levels

cannot exceed 65 dBA for more than 10 percent of the time or 60 dBA more than 50 percent of the

time.

The basic noise rules for other noise area classifications are:

Noise Area

Classification

Daytime

Nighttime

1.2 Noise area classifications

Noise area classifications (NAC) are based on the land use at the location of the person who hears the

noise, which does not always correspond with the zoning of an area. Therefore, noise from an industrial

facility near a residential area is held to the NAC 1 standards if it can be heard on a residential property.

Some common land uses associated with the NACs include:

NAC 1: Residential housing, religious activities, camping and picnicking areas, health services,

hotels, educational services

NAC 2: Retail, business and government services, recreational activities, transit passenger

terminals

NAC 3: Manufacturing, fairgrounds and amusement parks, agricultural and forestry activities

NAC 4: Undeveloped and unused land

Note that, although there is a NAC 4, there are no noise standards for these areas. The full list of NAC

land uses can be found starting on page 21 of this guide or in Minnesota Rule 7030.0050.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

1.3 Common noise concerns

By Minnesota law, the MPCA is empowered to enforce the state’s noise rules. Many other agencies and

levels of government, however, have an important role to play in upholding the noise standards.

Depending on the source and location of the noise, some agencies may be in a better position than

others to help citizens with noise concerns.

Industrial facilities

The MPCA enforces noise standards at facilities for which it has issued an air permit. For complaints

about noise at one of these facilities, please use the Online Citizen Complaints Form. If you prefer, you

may call the MPCA to make your complaint: 651-296-6300 within the Twin Cities metropolitan area or

1-800-657-3864 if you are outside of this area.

Local land uses

Local law enforcement agencies are empowered to enforce Minnesota state rules and laws relating to

the prevention and control of pollution (Minn. Stat. 115.071). Many local governments also have

nuisance noise ordinances or general public nuisance ordinances that can be used to enforce local noise

concerns.

Local governments are required to take reasonable measures to prevent the approval of land use

activities that will violate the state noise standard immediately upon establishment of the land use

(Minn. R. 7030.0030). Municipalities should consider the state noise standard when reviewing and

approving new projects in their jurisdiction. The MPCA can provide some expertise to support this

review process. Please contact noise.pca@state.mn.us.

Roads and highways

The Minnesota Department of Transportation (MnDOT) handles complaints about noise on highways

and other roads it manages. According to Minn. Stat. 116.07.2a, most roads are exempt from

Minnesota’s state noise rules. MnDOT does, however, have policies, agreed on with the MPCA, for

providing noise mitigation when it is determined to be both feasible and reasonable. MPCA reviews

some MnDOT projects and noise mitigation decisions. For further information on MnDOT’s noise

policies, please visit its website.

Vehicles

Minn. R.7030.1000-1060 outlines Minnesota’s state rules relating to motor vehicle noise. In addition to

the state rules, local governments may have nuisance sound ordinances, which are often easier to

enforce than the state rule. As with noise relating to local land-use decisions, contacting your local

government or law enforcement is your best course of action.

Airplanes

The Metropolitan Airports Commission (MAC) responds to all concerns regarding noise relating to

aircraft or the airports. For more information, please see its website.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Snowmobiles, off-highway vehicles, and motor boats

The Minnesota Department of Natural Resources (MDNR) has source-specific noise rules for

snowmobiles (Minn. R. 6100.5700.5), off-highway vehicles (Minn. R. 6102.0040.4), and motor boats

(Minn. Stat. 86B.321), requiring them to be equipped with proper mufflers and conform to certain noise

standards. For more information on MDNR regulations for snowmobiles, off-highway vehicles, and

boats, please visit its website.

Mining

The MDNR also has source-specific rules to restrict noise and vibrations from different types of metallic

mining operations (Minn. R. 6130.3900 and 6132.2900). Local governments are relied upon to consider

noise when approving and permitting sand and gravel mining operations. The MPCA enforces noise

standards at mining facilities for which it has issued an air permit. For complaints about noise at one of

these facilities, please use the Online Citizen Complaints Form. If you prefer, you may call the MPCA to

make your complaint: 651-296-6300 within the Twin Cities metropolitan area or 1-800-657-3864 if you

are outside of this area.

Gun clubs

Minn. Stat. 116.07.2a exempts gun clubs from the receiver-based noise standards administered by the

MPCA. However, Minn. Stat. 87A includes some standards regarding gun club noise. Through this

statute, the MDNR is authorized to regulate gun club noise. For further information, please visit its

website.

Motor vehicle race track

Minn. Stat. 116.07.2a exempts motor vehicle race tracks built before July 1, 1996 from Minnesota’s

noise standards. All tracks built since that date must comply with the noise rules. Local governments

have often been successful in working with exempt tracks to mitigate noise concerns by establishing

time and date restrictions, muffler requirements, and noise barriers.

1.4 Regulatory agencies

Several agencies have noise regulations for different noise sources. Noise rules either set standards

based on the source of the noise (source standards) or based on who hears the noise (receiver-based

standards).

Minnesota Pollution Control Agency - The MPCA has a receiver-based standard intended to limit noise

levels and protect the health and welfare of the general public. The MPCA enforces the standard at

facilities for which the agency issues air quality permits. The MPCA also works with other agencies and

levels of government to enforce noise standards and reduce violations through pre-construction project

reviews.

Local Agencies - Local governing agencies, such as a cities and counties, are relied upon to enforce noise

standards relating to local land use and often have ordinances regulating noise levels. They are also

responsible for not allowing land uses that would immediately violate the state noise standard. For

instance, local governments should be cautious of allowing a loud local utility facility to locate in a

residential area.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Minnesota Department of Natural Resources - The MDNR has source standards for snowmobiles,

motorboats, personal watercraft, off-highway vehicles, and gun clubs. MDNR also has source standards

for metallic mining operations. For more information, see its website.

Metropolitan Airport Commission - The MAC is responsible for all noise issues related to the

Minneapolis-St. Paul International Airport and reliever airports. For more information, see its website.

Federal Aviation Administration - The FAA has source regulations for commercial jet engines. All

commercial jet engines must meet noise emission criteria prior to being certified for flight. However, the

Metropolitan Airport Commission is the best contact for noise concerns related to its airports.

Additional information on the FAA’s noise standards can be found on its website.

Minnesota Department of Transportation – MnDOT is responsible for state highway noise mitigation. It

works with the Federal Highway Administration (FHWA) and the MPCA to evaluate road projects for

noise impacts and possible mitigation measures. For more information see the Department’s website.

Federal Highway Administration (FHWA) - The FHWA does not have actual noise standards, but has a

70 dBA L

guideline that is used to determine federal funding for noise abatement on highway projects.

New highway projects must go through a noise impact analysis and be considered for abatement

measures. Information on FHWA’s noise policies can be found on its website.

Federal Railroad Administration (FRA) - Regulation of railroad-related noise is the responsibility of the

FRA. For more information see the Administration’s website and to contact them about a noise concern,

call 1-800-724-5040.

Occupational Safety and Health Administration (OSHA) - OSHA has regulations to protect against

hearing loss in the workplace. These are “dose standards” that restrict the amount of noise an employee

receives over a period of time, such as eight hours. For additional information, visit OSHA’s website.

Housing and Urban Development (HUD) - HUD has noise regulations that establish acceptable noise

zones for HUD housing projects. More information can be found on HUD’s website.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

2. Basics of how sound works

2.1 Waves and sound pressure level

Sound travels in a wave motion through the air to our ears. A good way to imagine wave motion is with

a weight hanging from a spring. Picture the following diagram (Figure 1) as a single weight and spring

combination varying as time progresses along the horizontal axis.

In Figure 1 the first position of the weight on the spring is at rest with no forces exerted upon the

system. If the weight is raised above its point of rest and the progression of the weight moving down

and up again is observed over a period of time, a wave form is produced.

The amplitude of the moving weight is labeled as “A” in Figure 1 and corresponds with the maximum

movement of the weight from its “at rest” position to the peak of the wave form either up or down. We

hear changes in amplitude as changes in volume.

The period of the vibration is the amount of time taken to produce one complete cycle or, in this

example, how quickly the weight moves from top to bottom and back. The number of cycles per second

defines the frequency of the periodic (up and down) motion, which is given the unit of hertz, or Hz. We

hear different frequencies as higher or lower pitched sounds.

Figure 1. Weight on a spring – example of periodic motion

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Figure 2 shows how the weight on a string (two-dimensional) example of sound waves compares to the

compression and expansion of sound waves through space (three-dimensional).

The graphical representation of sound waves in Figure 2 is of pure tones, which are sounds made up of a

single frequency. A familiar example of a pure tone is the sound produced when a single key of a piano is

pressed. For instance, the middle C key on a piano vibrates the associated wire at a rate of

approximately 260 times per second or 260 Hertz. The vibration of the wire transfers its motion to the

sound board of the piano, which then vibrates at the same frequency, causing the air adjacent to the

sound board to form compression and expansion waves in the air emitting outward from the sound

board. When received by the human ear, this is regarded as sound. Most sounds are not pure tones, but

a mixture of tones of varying amplitude, frequency, and duration.

The intensity of a sound is the amount of sound energy at a given moment in a given area. The sound

pressure level, measured in a unit called the decibel, or dB, is the ratio between the intensity of a sound

and that of a reference pressure, which is the threshold of perception. The decibel is a logarithmic

measurement which can accommodate a large range of values. The human ear can detect sounds more

than a million times quieter than a jet aircraft during take-off; therefore, to have a system with a

manageable range of numbers, the logarithm is used.

Sound pressure level = 20 Log

* (Measured Sound Pressure / Reference Pressure)

Reference Pressure = 0.00002 Newtons / (meter)

Figure 2. Comparison of periodic motion to sound waves

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Many different properties affect the noise level of a specific source type. For example, three lawn

mowers may have three different noise levels because of differences in each specific piece of

equipment. Noise level also depends on the distance from the noise source and features of the

surrounding environment.

Figure 3 provides a rough estimate of decibel levels of some common noise sources.

2.2 Sound weighting networks

Sound level meters (SLM) used for monitoring can pick up sounds as a perfect computer, but the human

ear is not as precise. The human ear cannot hear very low frequencies or very high frequencies.

Weighting networks are used in noise monitors to adjust specific frequencies in the audio spectrum to

attempt to duplicate the response of the human ear.

The C-weighting network represents the actual sound pressure level that is received by the sound level

meter, and does not noticeably vary in its amount of compensation throughout the audio spectrum.

C-weighting is used during the calibration of sound level meters to ensure that the sound level displayed

on the meter is accurate and the same as the frequency of the calibrator.

The A-weighting network is used to duplicate the sensitivity of the human ear. At 100 Hertz, the

A-weighting network filters out approximately 20 dB from the incoming signal before it is combined with

the levels from the other frequency ranges to produce an A-weighted sound level.

Figure 3. Decibel levels of common noise sources

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

The graph in Figure 4 represents the sensitivity of the human ear in comparison to the compensation of

a C-weighting network and an A-weighting network. This illustration is useful in understanding how the

ear is inefficient in the detection of lower frequencies and is very sensitive to higher frequencies.

2.3 Human perception of sound

Sound has qualitative aspects that can be described with adjectives and quantitative aspects that can be

described with measurements. Sound can be qualitatively perceived as pleasant or annoying, and

quantitatively (as loudness) measured in terms of decibels.

Changes in loudness are described on a logarithmic scale because the human ear can hear such a wide

range of sound levels. The human ear can usually tell the difference when sound changes by 3 dBA and a

5 dBA change is clearly noticeable. Because of how the logarithmic scale functions in compressing the

measurements associated with sounds, an increase of 10 dBA sounds twice as loud.

Figure 4. Weighting networks with sound measurements done in the A-weighting

network are reported with the unit dBA

Figure 5. Change in decibel level and perceived change in loudness

± 1 dBA…………………….. Not Noticeable

± 3 dBA…………………….. Threshold of Perception

± 5 dBA…………………….. Noticeable Change

± 10 dBA…………………… Twice (Half) As Loud

± 20 dBA…………………… Four Times (One Fourth) As

Loud

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Figure 6. Distance attenuation of noise levels from a point source (top) and a line source (bottom)

2.4 Using decibel measurements

Addition and subtraction of decibels is often necessary for estimating total noise levels or background

noise. Because decibels are measured using a logarithmic scale, conventional linear mathematics cannot

be used. The following rules of thumb provide a good estimate of the effect that type, distance, and

number of sources have on measured sound pressure level.

Sound propagation and sources

Sources of sound can be defined as point or line sources, based on the way sound pressure waves

spread away from the source. Sound waves move out from sources in a way similar to waves traveling

away from a rock dropped in a pond. A point source, like a factory, emits sound that spreads out in a

sphere. A line source, like a busy highway, emits sound that spreads out in a cylinder. Knowing the

sources of sounds makes it possible to make assumptions about how the sound behaves.

Distance attenuation

Over distance, sound attenuates, or is reduced in amplitude, and is perceived as becoming quieter. This

occurs as the sound travels outward to an increasingly larger sphere or cylinder, and the energy per unit

of area decreases. These basic principles allow us to make generalized assumptions about sound.

When the distance is doubled from a line source, the sound level decreases three decibels.

Example: If a sound level is: 70 decibels at 50 feet it will be

67 decibels at 100 feet, and

64 decibels at 200 feet

When the distance is doubled from a point source, the sound level decreases six decibels (Figure 6).

Example: If a sound level is: 70 decibels at 50 feet it will be

64 decibels at 100 feet, and

58 decibels at 200 feet

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Number of sources

In many situations pertaining to noise control and monitoring, it is very useful to be able to add and

subtract multiple sources of sound. This can be done with principles similar to how sound attenuation

over distance is estimated.

A doubling of sound energy yields an increase of three decibels. For example, each generator at a

factory produces sound that is measured at 70 decibels, so running one generator would create sound

measured at 70 dBA, turning on a second generator would increase sound by 3 dBA to 73 dBA, and

doubling again to four generators would increase sound levels to 76 dBA. Figure 7 illustrates this

principle.

In the same way, reducing the number of sources by half will reduce the sound pressure by 3 dBA.

Consider the perception of changes in decibel levels (Figure 5) compared to the example of addition or

subtraction of sources (Figure 7). Doubling sources yields an increase of 3 dBA, which is a change that is

just perceptible.

Background noise

Background, or ambient, noise consists of all noise sources other than the noise source of concern. This

can include traffic, animals, machinery, voices, and other sounds.

Wind is often a major source of ambient noise and can frequently be a problem when trying to monitor

a specific source of noise. The MPCA’s noise test procedures state that measurements should not be

made when noise from wind or precipitation results in a difference of less than 10 dBA between the

background sound level and noise source being measured. In practice, this means that wind speeds

must be below 11 mph when making noise measurements and rainy weather conditions should be

avoided. When background noise is less than 10 dBA from the decibel level of the noise source to be

measured, confidence in the accuracy of the measurement decreases.

Figure 7. Addition and subtraction of decibel levels

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

In certain instances, when a single noise source is analyzed along with other noise sources, correction

factors can be used to isolate the noise source being monitored and calculate its individual noise level.

This is done by measuring and recording the total noise level of all sources. Next, the noise source to be

isolated is turned off and a noise level reading is taken with all the other existing noise sources in

operation. The background noise level is then subtracted from the total noise level. The result is used in

conjunction with the following background noise correction chart (Figure 8) to find the approximate

noise level of the source.

Figure 8 is a graph used to estimate the amount of background noise influencing a measurement. Based

on the measured background noise it gives the corresponding decibel level to be subtracted from the

total measurement to determine the decibel level of the noise source being monitored.

For example, if the total noise level is 74 dBA, and then falls to 70 dBA when the source of interest is

turned off, the difference of four decibels between the total noise level and background noise indicates

that two decibels should be subtracted from the total. This means that a 72 dBA noise level can be

attributed to the monitored source in the absence of background noise.

Figure 8. Background noise correction

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

3. Measurement procedures

This guide contains two measurement procedures. The general protocols remain the same, but your

choice of procedure depends on the capabilities of your sound level meter (SLM). Noise Test Procedure

1 (NTP-1) should be used if your SLM is capable of calculating monitoring results and Noise Test

Procedure 2 (NTP-2) should be used if your SLM only displays instantaneous readings.

3.1 General procedures

Sound level meter

Your sound level meter and microphone must comply with the specifications for ANSI S1.4-1983 Type 0,

1, 2, or S.

Calibration

You must also have a calibrator of a known frequency and sound level. Calibrators should be compared

to a lab standard periodically. Calibration must be performed before and after the monitoring period.

Adjustments should be made if necessary.

Weather conditions

Measurements should not be made when noise from wind or precipitation results in a difference

between the background sound level and noise source being measured that is less than 10 dBA. In

practice, this means that wind speeds must be below 11 mph and rainy weather conditions should be

avoided. Temperature and humidity should be within equipment specifications.

Background noise

As mentioned in the previous section, background noise is any ambient noise other than the noise to be

measured, including wind, precipitation, traffic, etc. The difference between the sound level of the

source being monitored and that of the background noise must be less than 10dBA. See page 11 for

suggestions on how to correct for background noise.

Location of measurement

Properly choosing a monitoring location is an important consideration. Measurements should be made

in the appropriate NAC, at the area of normal outdoor human activity nearest to the noise source. The

monitoring location may not necessarily be at the property line; for instance, if the property of the

complainant is large and residential outdoor activity is limited to a backyard patio (possibly such as on a

farm).

Measurements must be made outdoors from at least three feet off of the ground (a tripod is helpful for

this). Another important part of site selection is the consideration of errors caused by reflecting objects,

such as a house or other large manmade or natural structures. Measurements should be made at least

as far away from any large reflecting object as from the noise source being measured. If this is not

possible, stay at least 30 feet from structures.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Documentation of measurement

A survey form must be completed containing date, time, location, noise source, wind speed/direction,

temperature, humidity, equipment information (make, model, serial number), site sketch with the

location of the noise source and measurement location (including appropriate distances), data and

calibration information. A sample survey form can be found on page 16.

3.2 Noise Test Procedure 1: Measurement procedure for non-

impulsive noise

The following test procedure has been approved by the Commissioner of the MPCA for the

measurement of non-impulsive noise. The general procedures described above (3.1 General procedures)

should be followed whether you are using the NTP-1 or NTP-2 procedures.

Instrumentation:

 Sound level meter and a microphone conforming to type 0, 1, 2, or S specifications under ANSI S1.4-

1983

 Calibrator of known frequency and level

 Small screwdriver for sensitivity adjustment

 Microphone windscreen

 Noise survey form

 Tripod (optional)

Monitoring procedure:

Monitoring must be conducted for at least a one hour time period. Sound meter must use the "A"

weighting and FAST response characteristics. Follow your manufacturer instructions to obtain the L

and L

results.

3.3 Noise Test Procedure 2: Manual measurement procedure for non-

impulsive noise

The following test procedure has been approved by the Commissioner of the MPCA for the

measurement of non-impulsive noise. The general procedures described above (3.1 General procedures)

should be followed whether you are using the NTP-1 or NTP-2 procedures. The NTP-2 procedure is to be

used with SLMs that cannot calculate noise statistics and only provide instantaneous readings.

Instrumentation:

 Sound level meter and a microphone conforming to type 0, 1, 2, or S specifications under ANSI S1.4-

1983

 Calibrator of known frequency and level

 Small screwdriver for sensitivity adjustment

 Microphone windscreen

 Noise survey form

 Tripod (optional)

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Manual monitoring procedure:

Using a hand-held SLM, take an instantaneous sound reading every 10 seconds and record on a data

sheet. A partner is very helpful.

Continue taking sound readings for one hour, which will give you 360 individual readings. Figure 9

provides an example of a manual monitoring data sheet.

To determine the L

, take the 36th loudest (10 percent of 360 = 36) individual sound reading by

counting from the loudest to the quietest on the data sheet. For example, in Figure 9, the L

= 63 and is

the 36th X from the top of the sheet.

To determine the L

, take the 180th loudest (50 percent of 360 = 180) individual sound reading. In

Figure 9, the L

= 57 and represents the 180th X from the top of the sheet.

Figure 9. Example manual monitoring data sheet

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Noise survey

Investigator ______________________________________ Date _________________________

SLM Manufacturer and Model _______________________ Serial Number_________________

Calibrator Manufacturer and Model ____________________________________________________

Calibrator Serial Number____________________________ Calibrator Frequency (Hz) ____________

Initial Calibration (dBA) ___________ Final Calibration (dBA) ___________

Meteorological Conditions: Wind Speed ________ Direction ________ Temperature________

Source ________________________________________________________________________

Monitor Location _______________________________________________________________

Time Start _______________ Time End _________________

Results L

_________dBA L

_________dBA

Diagram (Indicate noise source, receiver, microphone location, reflecting objects, obstructions,

landmarks, and distances)

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

4. Minnesota noise pollution statutes and rules

Minn. Stat. § 116.07 POWERS AND DUTIES.

Subdivision 1. Generally. In addition to any powers or duties otherwise

prescribed by law and without limiting the same, the Pollution Control Agency shall have

the powers and duties hereinafter specified.

Subd. 2. Adoption of standards. (c) The Pollution Control Agency shall also

adopt standards describing the maximum levels of noise in terms of sound pressure

level which may occur in the outdoor atmosphere, recognizing that due to variable

factors no single standard of sound pressure is applicable to all areas of the state. Such

standards shall give due consideration to such factors as the intensity of noises, the

types of noises, the frequency with which noises recur, the time period for which noises

continue, the times of day during which noises occur, and such other factors as could

affect the extent to which noises may be injurious to human health or welfare, animal or

plant life, or property, or could interfere unreasonably with the enjoyment of life or

property. In adopting standards, the Pollution Control Agency shall give due recognition

to the fact that the quantity or characteristics of noise or the duration of its presence in

the outdoor atmosphere, which may cause noise pollution in one area of the state, may

cause less or not cause any noise pollution in another area of the state, and it shall take

into consideration in this connection such factors, including others which it may deem

proper, as existing physical conditions, zoning classifications, topography,

meteorological conditions and the fact that a standard which may be proper in an

essentially residential area of the state, may not be proper as to a highly developed

industrial area of the state. Such noise standards shall be premised upon scientific

knowledge as well as effects based on technically substantiated criteria and commonly

accepted practices. No local governing unit shall set standards describing the maximum

levels of sound pressure which are more stringent than those set by the Pollution

Control Agency.

Subd. 2a. Exemptions from standards No standards adopted by any state

agency for limiting levels of noise in terms of sound pressure which may occur in the

outdoor atmosphere shall apply to (1) segments of trunk highways constructed with

federal interstate substitution money, provided that all reasonably available noise

mitigation measures are employed to abate noise, (2) an existing or newly constructed

segment of a highway, provided that all reasonably available noise mitigation measures,

as approved by the commissioners of the Department of Transportation and Pollution

Control Agency, are employed to abate noise, (3) except for the cities of Minneapolis

and St. Paul, an existing or newly constructed segment of a road, street, or highway

under the jurisdiction of a road authority of a town, statutory or home rule charter city,

or county, except for roadways for which full control of access has been acquired, (4)

skeet, trap or shooting sports clubs, or (5) motor vehicle race events conducted at a

facility specifically designed for that purpose that was in operation on or before July 1,

1996. Nothing herein shall prohibit a local unit of government or a public corporation

with the power to make rules for the government of its real property from regulating

the location and operation of skeet, trap or shooting sports clubs, or motor vehicle race

events conducted at a facility specifically designed for that purpose that was in

operation on or before July 1, 1996.

A Guide to Noise Control in Minnesota • November 2015 Minnesota Pollution Control Agency

Minn. Rules § 7030 NOISE POLLUTION CONTROL

7030.0010 INCORPORATION BY REFERENCE.

For the purpose of chapter 7030, American National Standards Institute, Specification

for Sound Level Meters, S1.4-1983 is incorporated by reference. This publication is

available from the American National Standards Institute, 1430 Broadway, New York,

N.Y. 10018 and can be found at: the offices of the Minnesota Pollution Control Agency,

1935 West County Road B-2, Roseville, Minnesota 55113; the Government Documents

Section, Room 409, Wilson Library, University of Minnesota, 309 19th Avenue South,

Minneapolis, Minnesota 55454; and the State of Minnesota Law Library, 25 Rev. Dr.

Martin Luther King Jr. Blvd., Saint Paul, Minnesota 55155. This document is not subject

to frequent change.

The Federal Highway Administration publication, Sound Procedures for

Measuring Highway Noise: Final Report, FHWA-DP-45-1R (August 1981) is incorporated

by reference. This publication is available from the United States Department of

Transportation, Federal Highway Administration, 1000 North Globe Road, Arlington,

Virginia 22201 and can be found at: the offices of the Minnesota Pollution Control

Agency, 1935 West County Road B-2, Roseville, Minnesota 55113; the Government

Documents Section, Room 409, Wilson Library, University of Minnesota, 309 19th

Avenue South, Minneapolis, Minnesota 55454; and the State of Minnesota Law Library,

25 Rev. Dr. Martin Luther King Jr. Blvd., Saint Paul, Minnesota 55155. This document is

not subject to frequent change.

7030.0020 DEFINITIONS.

Subpart 1. Application. The terms used in this chapter have the meanings given

them in this part.

Subp. 2. A-weighted. "A-weighted" means a specific weighting of the sound

pressure level for the purpose of determining the human response to sound. The

specific weighting characteristics and tolerances are those given in American National

Standards Institute S1.4-1983, section 5.1.

Subp. 3. Daytime. "Daytime" means those hours from 7:00 a.m. to 10:00 p.m.

Subp. 4. dB(A). "dB(A)" means a unit of sound level expressed in decibels (dB)

and A-weighted.

Subp. 5. Decibel. "Decibel" means a unit of sound pressure level, abbreviated as

dB.

Subp. 6. Impulsive noise. "Impulsive noise" means either a single sound

pressure peak (with either a rise time less than 200 milliseconds or total duration less

than 200 milliseconds) or multiple sound pressure peaks (with either rise times less than

200 milliseconds or total duration less than 200 milliseconds) spaced at least by 200

millisecond pauses.

Subp. 7. L

. "L

" means the sound level, expressed in dB(A), which is exceeded

ten percent of the time for a one hour survey, as measured by test procedures approved

by the commissioner.

Subp. 8. L

. "L

" means the sound level, expressed in dB(A), which is exceeded

50 percent of the time for a one hour survey, as measured by test procedures approved

by the commissioner.

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Subp. 9. Municipality. "Municipality" means a county; a city; a town; a regional

planning and development commission established under Minnesota Statutes, chapter

473; the metropolitan council; or other governmental subdivision of the state

responsible by law for controlling or restricting land use within its jurisdiction.

Subp. 10. Nighttime. "Nighttime" means those hours from 10:00 p.m. to 7:00

a.m.

Subp. 11. Person. "Person" means any human being, any municipality or other

governmental or political subdivision or other public department or agency, any public

or private corporation, any partnership, firm, association, or other organization, any

receiver, trustee, assignee, agency, legal entity, other than a court of law, or any legal

representative of any of the foregoing, but does not include the agency.

Subp. 12. Sound pressure level. "Sound pressure level", in decibels, means 20

times the logarithm to the base 10 of the ratio of the pressure to the reference

pressure. The reference pressure shall be 20 micronewtons per square meter.

7030.0030 NOISE CONTROL REQUIREMENT.

No person may violate the standards established in part 7030.0040, unless exempted by

Minnesota Statutes, section 116.07, subdivision 2a. Any municipality having authority to

regulate land use shall take all reasonable measures within its jurisdiction to prevent the

establishment of land use activities listed in noise area classification (NAC) 1, 2, or 3 in

any location where the standards established in part 7030.0040 will be violated

immediately upon establishment of the land use.

7030.0040 NOISE STANDARDS.

Subpart 1. Scope. These standards describe the limiting levels of sound

established on the basis of present knowledge for the preservation of public health and

welfare. These standards are consistent with speech, sleep, annoyance, and hearing

conservation requirements for receivers within areas grouped according to land

activities by the noise area classification (NAC) system established in part 7030.0050.

However, these standards do not, by themselves, identify the limiting levels of impulsive

noise needed for the preservation of public health and welfare. Noise standards in

subpart 2 apply to all sources.

Subp. 2. Noise standards.

Noise Area

Classification

Daytime

Nighttime

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7030.0050 NOISE AREA CLASSIFICATION.

Subpart 1. Applicability. The noise area classification is based on the land use

activity at the location of the receiver and determines the noise standards applicable to

that land use activity unless an exception is applied under subpart 3.

Subp. 2. Noise area classifications. The noise area classifications and the

activities included in each classification are listed below:

Noise Area

Classification

Land Use Activities

Household Units (includes farm houses)

Transient lodging

Group quarters

Mobile home parks or courts

Residential hotels

Other residential

Cultural activities and nature exhibitions

Medical and other health services

Correctional institutions

Educational services

Religious activities

Motion picture production

Entertainment assembly

Resorts and group camps

Camping and picnicking areas

(designated)

Other cultural, entertainment, and

recreational activities.

Railroad terminals (passenger)

Bus passenger terminals (intercity)

Railroad terminals (passenger and

freight)

Bus passenger terminals (local)

Rapid rail transit and street railway

passenger terminals

Bus passenger terminals (intercity and

local)

Other motor vehicle transportation

Marine terminals (passenger)

Airport and flying field terminals

(passenger)

Marine terminals (passenger and freight)

Airport and flying field terminals

(passenger

and freight)

Automobile parking

Telegraph message centers

Transportation services and

arrangements

Wholesale trade

Retail trade -- apparel and accessories

Retail trade -- building materials,

hardware, and farm equipment

Retail trade -- automotive, marine craft,

aircraft, and accessories

Retail trade -- general merchandise

Retail trade -- furniture, home

furnishings, and equipment

Retail trade -- food

Retail trade -- eating and drinking

Other retail trade

Finance, insurance, and real estate

services

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Personal services

Repair services

Business services

Legal services

Other professional services

Contract construction services

Governmental services (except

correctional institutions)

Miscellaneous services (except religious

activities)

Public assembly (except entertainment

assembly and race tracks)

Amusements (except fairgrounds and

amusement parks)

Recreational activities (except

designated camping and picnicking

areas)

Parks.

Food and kindred products --

manufacturing

Textile mill products -- manufacturing

Apparel and other finished products

made from fabrics, leather,

and similar materials -- manufacturing

Lumber and wood products (except

furniture) -- manufacturing

Furniture and fixtures -- manufacturing

Printing, publishing, and allied industries

Paper and allied products --

manufacturing

Chemicals and allied products --

manufacturing

Petroleum refining and related industries

Primary metal industries

Rubber and miscellaneous plastic

products -- manufacturing

Stone, clay, and glass products --

manufacturing

Professional, scientific, and controlling

instruments; photographic and optical

goods; watches and clocks --

manufacturing

Railroad, rapid transit, and street railway

transportation (except passenger

terminals)

Miscellaneous manufacturing (except

motion picture production)

Fabricated metal products --

manufacturing

Motor vehicle transportation (except

passenger terminals)

Aircraft transportation (except passenger

terminals)

Marine craft transportation (except

passenger and freight terminals)

Communication (except telegraph

message centers)

Highway and street right-of-way

Utilities

Race tracks

Fairgrounds and amusement parks

Agricultural

Agricultural and related activities

Fishing activities and related services

Other transportation, communication,

and utilities (except transportation

services and arrangements)

Forestry activities and related services

(including commercial forest land, timber

production, and other related activities)

All other activities not otherwise listed.

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Undeveloped and unused land area

(excluding non-commercial forest

development)

Non-commercial forest development

Water areas

Vacant floor area

Under construction

Other undeveloped land and water

areas.

Subp. 3. Exceptions. The noise area classification for a land use may be changed

in the following ways if the applicable conditions are met.

A. The daytime standards for noise area classification 1 shall be applied to

noise area classification 1 during the nighttime if the land use activity does not include

overnight lodging.

B. The standards for a building in a noise area classification 2 shall be

applied to a building in a noise area classification 1 if the following conditions are met:

(1) the building is constructed in such a way that the exterior to interior

sound level attenuation is at least 30 dB(A);

(2) the building has year-round climate control; and

(3) the building has no areas or accommodations that are intended for

outdoor activities

C. The standards for a building in a noise area classification 3 shall be

applied to a building in a noise area classification 1 if the following conditions are met:

(1) the building is constructed in such a way that the exterior to interior

sound level attenuation is at least 40 dB(A);

(2) the building has year-round climate control; and

(3) the building has no areas or accommodations that are intended for

outdoor activities.

D. The standards for a building in a noise area classification 3 shall be

applied to a building in a noise area classification 2 if the following conditions are met:

(1) the building is constructed in such a way that the exterior to interior

sound level attenuation is at least 30 dB(A);

(2) the building has year-round climate control; and

(3) the building has no areas or accommodations that are intended for

outdoor activities.

7030.0060 MEASUREMENT METHODOLOGY.

Subpart 1. Measurement location. Measurement of sound must be made at or

within the applicable NAC at the point of human activity which is nearest to the noise

source. All measurements shall be made outdoors.

Subp. 2. Equipment specifications. All sound level measuring devices must

meet Type O, I, II, or S specifications under American National Standards Institute S1.4-

1983.

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Subp. 3. Calibration. All sound level measuring devices must, at a minimum, be

externally field calibrated before and after monitoring using a calibration device of

known frequency and sound pressure level.

Subp. 4. Measurement procedures. The following procedures must be used to

obtain representative sound level measurements:

A. Measurements must be made at least three feet off the ground or

surface and away from natural or artificial structures which would prevent an accurate

measurement.

B. Measurements must be made using the A-weighting and fast response

characteristics of the sound measuring device as specified in American National

Standards Institute S1.4-1983.

C. Measurements must not be made in sustained winds or in precipitation

which results in a difference of less than ten decibels between the background noise

level and the noise source being measured.

D. Measurements must be made using a microphone which is protected

from ambient conditions which would prevent an accurate measurement.

Subp. 5. Data documentation. A summary sheet for all sound level

measurements shall be completed and signed by the person making the measurements.

At a minimum, the summary sheet shall include:

A. Date

B. Time

C. Location

D. Noise source

E. Wind speed and direction

F. Temperature

G. Humidity

H. Make, model, and serial number of measuring equipment

I. Field calibration results

J. Monitored levels

K. Site sketch indicating noise source, measurement location, directions,

distances, and obstructions.

7030.0070 SOUND ATTENUATION MEASUREMENT METHODOLOGY.

Subpart 1. Purpose. Sound level measurements made for assessing sound

attenuation as specified in part 7030.0050, subpart 3, item B, C, or D, shall be made

according to the requirements of this part.

Subp. 2. Equipment. The equipment shall meet the requirements specified in

part 7030.0060, subpart 2.

Subp. 3. Calibration. The equipment must meet the calibration requirements

specified in part 7030.0060, subpart 3.

Subp. 4. Measurement procedure.

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The measurement procedure described in FHWA-DP-45-1R, section 8 must be used for

determination of the sound attenuation.

Subp. 5. Equivalent methods. Methods equivalent to those described in subpart

4 may be used provided they are approved by the commissioner of the Minnesota

Pollution Control Agency. The commissioner shall approve an alternative method if the

commissioner finds that the method will produce representative data and results which

are as reliable as the methods specified in subpart 4.

7030.0080 VARIANCE.

If, upon written application of the responsible person, the agency finds that by reason of

exceptional circumstances strict conformity with any provisions of any noise rule would

cause undue hardship, would be unreasonable, impractical, or not feasible under the

circumstances, the agency may permit a variance upon the conditions and within the

time limitations as it may prescribe for the prevention, control, or abatement of noise

pollution in harmony with the intent of the state and any applicable federal laws.

7030.1000 DEFINITION.

"Motor vehicle" means any self-propelled vehicle not operated exclusively upon railroad

tracks and any vehicle propelled or drawn by a self-propelled vehicle and includes

vehicles known as trackless trolleys which are propelled by electric power obtained from

overhead trolley wires but not operated upon rails, except snowmobiles.

7030.1010 PROHIBITIONS.

Subpart 1. Operation of vehicle. No person shall operate either a motor vehicle

or combination of vehicles of a type subject to registration pursuant to Minnesota

Statutes, chapter 168 at any time or under any condition of grade, load, acceleration, or

deceleration in such a manner as to exceed the noise limits contained herein for the

category of motor vehicle and speed limits specified, when tested with a measurement

procedure approved by the commissioner.

Subp. 2. Sale of vehicle. No person shall sell or offer for sale a new motor

vehicle or combination of vehicles of a type subject to registration pursuant to

Minnesota Statutes, chapter 168 which when maintained according to the

manufacturer's specifications would exceed the noise limits contained herein for the

category of motor vehicle and speed limits specified, when tested with a measurement

procedure approved by the commissioner.

Subp. 3. Modification of vehicle. No person shall modify a motor vehicle or

combination of vehicles of a type subject to registration pursuant to Minnesota

Statutes, chapter 168 in a manner which will amplify or increase the noise emitted by

the vehicle, above the noise limits contained herein for the category of motor vehicle

and speed limits specified, when tested with a measurement procedure approved by

the commissioner. No person shall operate a motor vehicle so modified.

Subp. 4. Sale of parts. No person shall sell or offer for sale replacement or

additional parts for a motor vehicle or combination of vehicles of a type subject to

registration pursuant to Minnesota Statutes, chapter 168 which when installed in the

vehicle will amplify or increase the noise emitted by the vehicle, above the noise limits

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contained herein for the category of motor vehicle and speed limits specified, when

tested with a measurement procedure approved by the commissioner. No person shall

operate a motor vehicle incorporating such parts.

7030.1020 SCOPE.

This chapter applies to the total noise from a vehicle or combination of vehicles of a

type subject to registration pursuant to Minnesota Statutes, chapter 168 and shall not

be construed as limiting or precluding the enforcement of any other provision of law

relating to motor vehicle exhaust noise.

7030.1030 EXCEPTIONS.

Vehicles under parts 7030.1050 and 7030.1060 are allowed to exceed the noise limits

contained herein when performing acceleration maneuvers for safety purposes.

7030.1040 NOISE LIMIT FOR VEHICLES OVER 10,000 POUNDS.

Motor vehicle noise limits for vehicles with a manufacturer's gross vehicle weight rating

of more than 10,000 pounds and any combination of vehicles towed by such motor

vehicle.

A. Speed limits greater than 35 mph.

B. Speed limits equal to or less than 35 mph and stationary run-up tests (for

vehicles with governed engines). For stationary run-up tests on all-paved surfaces, add 2 dBA.

C. Speed limits equal to or less than 35 mph and stationary run-up tests (for

vehicles with governed engines), for vehicles manufactured on or after January 1, 1978. For

stationary run-up tests on all-paved surfaces, add 2 dBA.

D. Speed limits equal to or less than 35 mph and stationary run-up tests (for

vehicles with governed engines), for vehicles manufactured on or after January 1, 1982. For

stationary run-up tests on all-paved surfaces, add 2 dBA.

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7030.1050 MOTOR VEHICLE NOISE LIMITS FOR MOTORCYCLES.

A. For vehicles manufactured before January 1, 1975.

B. Speed limits greater than 35 mph for vehicles manufactured on or after

January 1, 1975.

C. Speed limits equal to or less than 35 mph for vehicles manufactured on or after

January 1, 1975.

7030.1060 NOISE LIMITS FOR OTHER VEHICLES.

Motor vehicle noise limits for any other motor vehicle not included under parts

7030.1040 and 7030.1050 and any combination of vehicles towed by such motor

vehicle.

Minn. Stat. § 86B WATERCRAFT OPERATION

86B.321 NOISE LIMITS.

Subdivision 1. Operation in excess of noise limits prohibited. A person may not

operate a motorboat under any condition of load, acceleration, or deceleration in a

manner that exceeds the noise limits contained in subdivision 2.

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Subd. 2. Noise limits. (a) The noise limits for the total noise from the marine

engine or motorboat may not exceed:

(1) for marine engines or motorboats manufactured before January 1, 1982, a

noise level of 84 decibels on the A scale measured at a distance of 50 feet from the

motorboat or equivalent noise levels at other distances as specified by the

commissioner in a pass-by test or 86 decibels on the A scale measured at idle in a

stationary test at least four feet above the water and at least four feet behind the

transom of the motorboat being tested; and

(2) for marine engines or motorboats manufactured on or after January 1, 1982, a

noise level of 82 decibels on the A scale measured at a distance of 50 feet from the

motorboat or equivalent noise levels at other distances as specified by the

commissioner in a pass-by test or 84 decibels on the A scale measured at idle in a

stationary test at least four feet above the water and at least four feet behind the

transom of the motorboat being tested.

(b) The noise limits in paragraph (a) do not preclude enforcement of other laws

relating to motorboat noise. The officer or deputy doing the testing shall determine

which test or tests shall be used. Failure to pass either the pass-by or stationary idle test

is a violation of this section.

commissioner by written order and published in the State Register. The noise level

determinations are exempt from the rulemaking provisions of chapter 14 and section

14.386 does not apply.

Subd. 3. Applicability. The provisions of this section do not apply to motorboats

operating under a permit issued under section 86B.121 or a United States Coast Guard

marine event permit in a regatta or race while on trial runs or while on official trials for

speed records during the time and in the designated area authorized by the permit.

86B.521 MOTORBOAT NOISE CONTROL.

Subdivision. 1. Exhaust muffling system required. A motor may not be used on

a motorboat unless it is equipped with an efficient muffler, underwater exhaust, or

other device that adequately muffles or suppresses the sound of the exhaust of the

motor so as to prevent excessive or unusual noise. A motor may not be equipped with

an altered muffler, muffler cutout, muffler bypass, or any other device designed or

installed so that it can be used to continually or intermittently bypass any muffler or

muffler system installed in the motorboat or to reduce or eliminate the effectiveness of

such a muffler or muffler system.

Subd. 2. Sale of motor that exceeds noise limits prohibited.

A person may not sell or offer for sale a marine engine or motorboat that would exceed

the noise limits contained in section 86B.321, subdivision 2, under a test procedure

approved by the commissioner if the motor is maintained according to the

manufacturer's specifications.

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Subd. 3. Modification of engine to exceed noise limits prohibited. (a) A person

may not modify a marine engine or motorboat in a manner that will amplify or increase

the noise emitted by the marine engine or motorboat above the noise limits contained

in section 86B.321, subdivision 2, under a test procedure approved by the

commissioner.

(b) A person may not operate a motorboat with an engine modified to increase

noise above the noise limits.

Subd. 4. Sale of parts that cause excessive noise prohibited. (a) A person may not

sell or offer for sale replacement or additional parts for a marine engine or motorboat

which when installed in the marine engine or motorboat will amplify or increase the

noise emitted by the marine engine or motorboat above the noise limits contained in

section 86B.321, subdivision 2, under a test procedure approved by the commissioner.

(b) A person may not operate a motorboat incorporating parts prohibited to be

sold under paragraph (a).

Subd. 5. Applicability. The provisions of this section do not apply to motorboats

operating under a permit issued under section 86B.121 or a United States Coast Guard

marine event permit in a regatta, or race, while on trial runs, or while on official trials

for speed records during the time and in the designated area authorized by the permit.

Subd. 6. Rulemaking exemption. The test procedures under subdivisions 2, 3, and

4 shall be established by written order by the commissioner and published in the State

provisions of chapter 14 and section 14.386 does not apply.

Minn. Stat. § 84.8 SNOWMOBILES

84.871 EQUIPMENT REQUIREMENTS.

Subdivision. 1. Mufflers. Except as provided in this section, every snowmobile

shall be equipped at all times with a muffler in good working order which blends the

exhaust noise into the overall snowmobile noise and is in constant operation to prevent

excessive or unusual noise. The exhaust system shall not emit or produce a sharp

popping or crackling sound. This section does not apply to organized races or similar

competitive events held on (1) private lands, with the permission of the owner, lessee,

or custodian of the land; (2) public lands and water under the jurisdiction of the

commissioner of natural resources, with the commissioner's permission; or (3) other

public lands, with the consent of the public agency owning the land. No person shall

have for sale, sell, or offer for sale on any new snowmobile any muffler that fails to

comply with the specifications required by the rules of the commissioner after the

effective date of the rules.

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6100.5700 REQUIRED EQUIPMENT.

Subp. 5. Mufflers. Mufflers:

A. No person shall operate a snowmobile unless it is equipped with a muffler as

required by law and these rules, except that snowmobiles may be operated in organized

events as authorized by Minnesota Statutes, section 84.871, without such a muffler.

B. No snowmobile manufactured on or after June 30, 1970, and before February

1, 1972, for sale in Minnesota, except snowmobiles designed for competition purposes

only, shall be sold, or offered for sale, unless it is equipped with a muffler that limits

engine noise to not more than 86 decibels on the A scale at 50 feet.

C. No snowmobile manufactured on or after February 1, 1972, for sale in

Minnesota, except snowmobiles designed for competition purposes only, shall be sold,

or offered for sale, unless it is equipped with a muffler that limits engine noise to not

more than 82 decibels on the A scale at 50 feet.

D. No snowmobile manufactured on or after April 1, 1975, except a snowmobile

designed for competition purposes only, shall be sold, offered for sale, or operated in

Minnesota unless it is so equipped and has been certified by the manufacturer to

conform to a sound level limitation of not more than 78 decibels on the A scale at 50

feet as originally equipped.

E. In certifying that a new snowmobile complies with the noise limitation

requirements of this rule, a manufacturer shall make such a certification based on

measurements made in accordance with the SAE Recommended Practice J192(a), as set

forth in the Report of the Vehicle Sound Level Committee, as approved by the Society of

Automotive Engineers September 1970 and revised November 1973.

F. No snowmobile shall be sold or offered for sale in Minnesota unless its maker

has previously furnished the commissioner with a certificate of compliance certifying

that all snowmobiles made by that maker meet or exceed the applicable noise level

restrictions established by these rules. The certification of compliance shall be in the

form of a "Snowmobile Safety Certification Committee" label conspicuously attached to

the machine showing certification by the Snowmobile Safety and Certification

Committee, Inc., or a label showing compliance with Snowmobile Safety Certification

Committee standards accompanied by a letter containing test results of an evaluation of

noise levels by a competent independent testing laboratory. Snowmobiles intended for

competition purposes only shall be exempt from this part provided a separate placard

identifying that such snowmobile is not so equipped is conspicuously and permanently

affixed thereto.

G. Except for organized events as authorized by Minnesota Statutes, section

84.871, no snowmobile shall be modified by any person in any manner that shall amplify

or otherwise increase total noise level above that emitted by the snowmobile as

originally equipped, regardless of date of manufacture.

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Minn. Stat. § 87A. SHOOTING RANGES

87A.05 NOISE STANDARDS.

Allowable noise levels for the operation of a shooting range are the levels determined

by replacing the steady state noise L

and L

state standards for each period of time

within each noise area's classification with a single Leq(h) standard for impulsive noise

that is two dBA lower than that of the L

level for steady state noise. The noise level

shall be measured outside of the range property at the location of the receiver's activity

according to Minnesota Rules, parts 7030.0010 to 7030.0080, as in effect on May 28,

2005. For purposes of this section, "Leq(h)" means the energy level that is equivalent to

a steady state level that contains the same amount of sound energy as the time varying

sound level for a 60-minute time period.

Minn. Rules § 6102, RECREATIONAL VEHICLES

6102.0002 DEFINITIONS.

Subpart 1. Scope. For the purposes of parts 6102.0002 to 6102.0080, the terms

defined in this part have the meanings given them.

Subp. 2. ATV. "ATV" means an all-terrain vehicle.

Subp. 3. Commissioner. "Commissioner" means the commissioner of Natural

Resources.

Subp. 4. Department. "Department" means the Department of Natural

Resources.

Subp. 5. OHM. "OHM" means an off-highway motorcycle.

Subp. 6. ORV. "ORV" means an off-road vehicle.

Subp. 7. Vehicle. "Vehicle" means an OHM, ORV, or ATV.

6102.0040 REQUIRED EQUIPMENT.

Subp. 4. Mufflers.

A. No person shall operate a vehicle unless it is equipped with a muffler

having a spark arrestor approved by the United States Forest Service as described by

Code of Federal Regulations, title 36, chapter II, section 261.52, paragraph (j).

B. Vehicles shall not be sold, offered for sale, or operated in this state

unless equipped so that overall noise emission does not exceed a sound level limitation

of not more than 99 decibels on the A scale from a distance of 20 inches using test

procedures and instrumentation as set forth in the Society of Automotive Engineers'

Standard, SAE J1287, June 1988, or, if different procedures or instrumentation are used,

a noise level equivalent to that level.

C. No noise suppressing system or muffler shall be equipped with a

cutout, bypass, or similar device and no person shall modify or alter that system or its

operation in any manner which will amplify or increase the noise emitted by the

vehicle's motor to exceed the noise limits established in this subpart, except for

organized events as authorized by Minnesota Statutes, sections 84.795, subdivision 7;

84.804, subdivision 5; and 84.928, subdivision 5.