The purpose of this Informal Report is to provide City Council with information about proposed changes to the City s noise ordinance.

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1 INFORMAL REPORT TO THE CITY COUNCIL MEMBERS To the Mayor and Members of the City Council June 29, 2012 SUBJECT: NOISE ORDINANCE REVISION ISSUED BY THE CHIEF OF POLICE MINERAL WELLS, TEXAS SUMMARY The purpose of this Informal Report is to provide City Council with information about proposed changes to the City s noise ordinance. An important goal of community policing is to improve the quality of life. Among the issues found affecting this subject here in Mineral Wells are the numerous citizen complaints about noise-related disturbances. A noise is defined as any sound which negatively impacts the community environment and is considered an annoyance or nuisance, thus diminishing the quality of life. Researching available enforcement and educational remedies on this matter, staff expressed concerns about the subjective nature of the current noise ordinance, specifically the difficulty in fair standards of enforcement. Interpreting a noise violation in the context of a nuisance, there is a certain amount of perceptual value and opinion required under the current ordinance structure. This Informal Report outlines the research conducted and proposes elements for a new noise ordinance that will provide objective measures and seek to protect the property interests of involved parties within the various zoning districts of this community. The decibel (dba) levels are based on results from research conducted at one of the higher volume call locations regarding noise complaints and comparative information from other cities noise ordinance provisions. BACKGROUND Reported disturbance calls to police are historically a high volume police activity in many urban and suburban areas. Researching the Mineral Wells Police dispatch records found there were nearly 1800 citizen-initiated calls for service reporting a disturbance during year This figure accounted for approximately 12% of all calls for service that year. Of these, there were a significant number related to reports of disturbing noise or loud music, which were found to be approximately 30% of the total number of disturbance calls reported. This high volume call activity issue has continued into this current year. Examining the issue further, one location is considered prominent for repeat disturbance calls to police. Of the 132 disturbance calls reported to police this year-to-date, Fuzzy s Taco Shop, located at 306 N. Oak Avenue, was the related call location in 26% of all citizen-initiated calls for service reporting a disturbance. Of that number, 29 calls were directly related to reports of loud music or loud noise coming from that location. Officers have responded to the location and made every attempt to restore the peace; however, staff has expressed concern over their inability to enforce the current

2 ordinance due to the subjective nature of the current ordinance and lack of any objective measures to cite in documenting violations other than perceptual values alone. In April, 2012, after meeting with the business owners and other concerned citizens with properties abutting or in the vicinity of this location, a noise impact study of the downtown Central Business District was conducted by the police department staff. Call records indicated the issues specific to the reported disturbances at Fuzzy s Taco Shop were in regards to live music and amplified karaoke contests on certain nights of the week (Wednesday) and weekend (Friday and Saturday) where the amplified speakers were either placed out on the patio or noise emitting from the business was allowed to escape the business structural boundaries through a set of open patio doors adjacent to an interior bar area. The acoustical environment at this venue is also particularly concerning, as it contains an open-air patio which is enclosed by exterior brick walls that provide a recipe for a perfect acoustical storm. Staff conducted twenty business checks between April 6 th and May 9 th. During this period, decibel measurements were documented on 16 occasions and prepared in a summary report graph (see attachment Sound Measurements Fuzzy s Taco Shop). Shortly before concluding this study, the business management was allowed to host one live event on the open-air patio for comparative purposes (NOTE: The Sound Measurement Fuzzy s Taco Shop on May 5 th shows a reading of 103 dba this was directly attributable to the open-air use of amplified loud speaker utilized by the band) This statistic should be excluded and classified as a statistical anomaly for controlled study of the overall acoustical effect in this open-air environment specific to this noise impact study. The results of the noise impact study found that the live or amplified music emanating from the Fuzzy s Taco Shop could be perceived as negatively impacting the community environment when allowed to escape from the business curtilage and into the public domain or properties abutting the location. Applying objective measurement gathered from the study, the ambient noise levels at this location averaged 63.1 dba when measured at times other than when live music or amplified karaoke was present. Between 07:00 a.m. and 10:00 p.m., the average ambient noise level was 70.3 dba, measured outside of the front of the business on the public sidewalk, with 71 dba being the highest peak measurement recorded at 9:49 p.m. The average ambient noise level was 71.4 dba between 10:00 p.m. and 1:00 a.m., taken from the same location on the public sidewalk, with 79 dba being the highest peak measurement recorded at 10:45 p.m. Ambient sound levels between 1:00 a.m. and 7:00 a.m. averaged 58.1 dba. These ambient levels were consistent during the late night hours throughout a two-square block measurement distance from the source location. In the alleyway, at the bounding real property line where residences adjoining this location, the average ambient sound levels were 69.6 dba, between 7:00 a.m. and 10:00 p.m., with 75 dba being the highest peak measurement recorded at 9:20 p.m. Between 10:00 p.m. and 1:00 a.m., the average was 68.2 dba, with 92 dba being the highest peak measurement recorded at 10:17 p.m. Between 1:00 a.m. and 7:00 a.m. ambient levels mirrored those from in front of the business and for the area.

3 The noise impact study and graph provided include proposed decibel levels of 75 dba allowable between the hours of 7:00 a.m. and 10:00 p.m., and 65 dba allowable between 10:00 p.m. and 7:00 a.m. the following day. These levels would apply to the Commercial Business District and any Planned Development zoning districts for the City of Mineral Wells. The recommended levels are based upon the results gathered during this period of empirical research and comparative information from other municipal ordinances (see attached Texas Municipal Code of Ordinances [Reference Group Sample]). The maximum sound level permissible under state law is 85 dba. Any measurements above this level are defined as a nuisance. Another issue on the subject of noise is the number of complaints received regarding animals, specifically barking dogs and birds or fowl. The current ordinance lacks enforceable measure in regard to defining frequent or long continued noise. The proposed ordinance quantifies this issue with specific measurement for continuous noise from an animal in sustained duration exceeding ten (10) minutes or longer. Finally, the current ordinance does not include provisions for construction noises limiting any Saturday or Sunday activities. The proposed ordinance expands the current limits to include and address weekend day(s) limitations with time parameters applied. RECOMMENDATION Consider the proposed repeal and revision of the current noise ordinance. Hold a public hearing on the subject to solicit community feedback and input. Approve the new ordinance upon the completion of the public hearing process with any addendums incorporated into the proposed noise ordinance revision. If you have any questions, please contact me at (940) Dean A. Sullivan Chief of Police Attachments: A complete draft of the proposed ordinance revision is included for consideration and possible public hearing by the City Council. Sound Measurements Fuzzy s Taco Shop Noise Impact Study Chart and Graphs of site plan from measurement level points along with ambient measurement levels Comparative table of other Texas Municipal Code of Ordinances (Reference Group Sample) Fundamentals of Environmental Acoustics (Abridged) with tables

4 ORDINANCE NO. AN ORDINANCE REPEALING AND REPLACING ARTICLE III - NOISE OF CHAPTER 42, ENVIRONMENT OF THE CODE OF THE CITY OF MINERAL WELLS, TO AMMEND AND REVISE THE NOISE ORDINANCE TO INCLUDE DECIBEL LEVELS AND TIME PARAMETERS; TO ADD DEFINITIONS RELATED TO NOISE; TO SET MAXIMUM SOUND LEVELS BASED ON ZONING CATEGORIES; TO REGULATE AMPLIFIERS IN THE RIGHT OF WAY; TO RESTRICT ANIMAL NOISE; TO ALLOW EXCEPTIONS, PROVIDING THAT THIS ORDINANCE SHALL BE CUMULATIVE OF ALL ORDINANCES; PROVIDING A SAVINGS CLAUSE; PROVIDING A SEVERABLIITY CLAUSE; PROVIDING A PENALTY CLAUSE; PROVIDING FOR PUBLICATION AND NAMING AN EFFECTIVE DATE. WHEREAS, it is the policy of the City of Mineral Wells to minimize the exposure of citizens to excessive noise and to protect, promote and preserve the public health, comfort, convenience, safety and welfare; and WHEREAS, it is the intent of the City to control the level of noise in a manner which promotes commerce; protects the sleep and repose of citizens; promotes the use, value and enjoyment of property; and preserves the quality of the environment; and WHEREAS, it is desirable to address common noise complaints caused by repetitive and excessive noise by adding maximum decibel levels and by adding restrictions on noise from animals and from amplifiers in public right-of-way; NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY OF MINERAL WELLS, TEXAS:

5 ARTICLE III. NOISE Sec Noise General Provisions. 1. Scope. This Section applies to the control of all sound and noise within the City of Mineral Wells. 2. Overview. This Section is designed to regulate noise by various alternative means in order to allow the enforcement of noise regulations. A noise may be in violation of this Section because it is disturbing to a reasonable person of ordinary sensibilities or because it exceeds the decibel level restrictions provided below. If a noise violates more than one of these provisions, the violation will be enforced under whichever provision is most applicable to the situation as determined by the enforcement officer of the City. Sec Definitions. Ambient noise shall mean the all-encompassing noise level associated with a given environment, being a composite of sounds from all sources at the location, constituting the normal or existing level of environmental noise at a given location. A-Weighting (dba) shall mean the sound pressure level in decibels as measured on a sound level meter using the A-weighted network. The level so read is designated db(a) or dba. Bounding real property line shall mean an imaginary line at the ground and its vertical extension which separates the real property owned, occupied, or used by one person or entity from that owned, occupied, or utilized by another person or entity.

6 Decibel (dba) shall mean the unit of measurement for sound pressure at a specified location. Governmental function shall mean work conducted by a governmental entity, including its employees or agents, in the interest of the community. Person shall mean a natural person or association of natural persons, trustee, receiver, partnership, corporation, organization, or the manager, agent, servant, or employee of any of them. Sound level shall mean the instantaneous sound pressure level measured in decibels obtained by the use of a sound level meter set for A-weighting on slow integration speed, unless otherwise noted. Time shall mean: whenever certain hours are named herein, they shall mean Central Standard Time or Daylight Saving Time as may be in current use in the City. Unreasonable noise shall mean: (1) Any unreasonably loud, disturbing, and unnecessary noise which causes material distress, discomfort or injury to persons of ordinary sensibilities in the immediate vicinity thereof; or (2) Any noise of such character, intensity and continued duration, which substantially interferes with the comfortable enjoyment of private homes by persons of ordinary sensibilities. Zoning districts shall mean: Residential shall mean: property zoned for residential use in accordance with the City s zoning ordinance (ie. SF-E, SF-9, SF-6, MD, MF, MH), or Non-residential shall mean: all other property not zoned for residential use in accordance with the City s zoning ordinance (ie. A, LB, GR, C, BP, LI, HI, WP-A), or

7 Mixed Use shall mean: all other property zoned for the concurrent use of commercial and residential structures in accordance with the City s zoning ordinance (ie. CBD, PD, WP- B). Sec Restrictions on Decibel Levels. (1) Maximum sound levels. During the times and in the zoning districts set out below, the activities that create a sound pressure level on the complainant s bounding real property line that exceeds the maximum allowable sound level (dba) listed herein are declared to be public nuisances. Regardless of the measurable db(a) level established herein as provided by this Ordinance, the generation of any sound at a level greater than 85 decibels (dba) is presumed to be unreasonable if it occurs in a public place or near a private residence, in accordance with state statute, and after the person making the noise receives notice from a magistrate or peace officer that the noise is a public nuisance. All residential (SF-E, SF-9, SF-6, MD, MF, MH) zoning districts: Daytime: 7:00 a.m. to 10:00 p.m. = 70 dba Nighttime: 10:00 p.m. to 7:00 a.m. = 60 dba All non-residential (ie. A, LB, GR, C, BP, LI, HI, WP-A) zoning districts: Daytime: 7:00 a.m. to 10:00 p.m. = 80 dba Nighttime: 10:00 p.m. to 7:00 a.m. = 70 dba All mixed use (ie. CBD, PD, WP-B) zoning districts: Sunday Thursday Daytime: 7:00 a.m. to 10:00 p.m. = 75 dba Nighttime: 10:00 p.m. to 7:00 a.m. the following day = 65 dba

8 Friday Saturday Daytime: 7:00 a.m. to 12:00 Midnight = 75 dba Nighttime: 12:00 Midnight to 7:00 a.m. the following day = 65 dba ALL zoning districts where existing ambient noise levels are found to exceed the prescribed maximum level: 7:00 a.m. to 10:00 p.m. = Existing Ambient (dba) + 3 dba 10:00 p.m. to 7:00 a.m. = Existing Ambient (dba) (2) Method of noise measurement. Noise measurements shall be a minimum of 30 seconds in duration using an A-weighting scale on the slow meter response setting as specified by the American Standards Association. Decibel levels are measured from the complainant s bounding real property line or at a distance of fifty (50) feet if in a public place. For residential districts adjacent to other districts, the residential decibel levels apply when measured from a residential complainant s bounding real property line. Where the complainant s bounding real property line is not clearly identifiable, measurement will be taken from within the complainant s real property standing at the point where the audible noise disturbance is detectable. Violations will be determined based on the highest registered reading in that measurement period. All measurement levels will be inclusive of any ambient noise that exists at the time of the measurement. Sec Unreasonable Noise Prohibited. (1) In addition to the other noise restrictions in this Section, no person shall make, cause, suffer, allow or permit unreasonably loud noises in such a manner, or with such volume, intensity or duration, so as to disturb a reasonable person of ordinary sensibilities. While portions of this Ordinance prohibit sound over a certain decibel limit, a decibel level may not be required for the enforcement of this subsection. (2) This subsection is intended to apply to, but is not limited to, unreasonable noises in the form of:

9 a. Amplifiers or amplified sound in the Public ROW and on City Property. The use of a bullhorn, loudspeaker, or other sound amplification is prohibited in the public right-of-way and on City of Mineral Wells property, unless permitted as an exception below. Exceptions: i. Public safety officials and their employees while performing their duties. ii. Persons or entities with written permission from the City Manager or designee to operate amplified sound equipment associated with a recognized public event that produces sound audible beyond the bounding real property line of the source venue in excess of the limits prescribed herein as outlined, not to exceed the maximum levels prescribed. b. Animals. It shall be unlawful to keep, or to permit the keeping of, any dog(s) or rooster(s) or any other bird or animal that creates any bark, cry, crow, or other sound on a frequent, repetitive or continuous basis for ten (10) minutes or longer. c. Construction Work. Noise created by construction work within three hundred (300) feet of an occupied residential structure involving the erection, excavation, demolition, alteration, or repair of any building, structure, or flatwork is prohibited as follows: Before 7:00 a.m. or after 6:00 p.m. Monday-Friday Before 9:00 a.m. or after 6:00 p.m. Saturday-Sunday d. Music. The playing of any music or musical instrument in such manner or with such volume or bass, in accordance with the limits described in Section 42-63: Restrictions on Decibel Levels above, as to annoy or disturb the quiet, comfort or repose of persons of ordinary sensibilities in any dwelling, hotel/motel or other type of residence.

10 e. Horns or other signal devices. The continued or frequent sounding of any horn, air horn, or signal device on any vehicle except as a danger or warning signal; the creation by means of any such signal device of any unreasonably loud or harsh noise for any unnecessary and unreasonable period of time. f. Operation of motor vehicles. The revving of any engine, the use of an engine brake, the playing of any music with such volume or bass, or the operation of any vehicle so out of repair, so loaded or in such manner as to create loud or unnecessary grating, grinding, jarring, rattling, or squealing noise or vibrations is prohibited. This includes the discharge in the open air of the exhaust of any steam engine, stationary internal-combustion engine, motor vehicle or motorboat engine, except through a muffler or other device which will effectively prevent loud or explosive noises therefrom. Sec Exemptions. The following acts and sounds shall be exempt from the requirements of this Section: 1. Noise generated due to normal building conditioning and ventilation and property maintenance. 2. Noise generated on public property, school property, and those areas zoned as community facilities (CF) as permitted by the property owner. 3. Noise generated by authorized permit granted by the City Manager or designee as described above. (See Sec Unreasonable Noise Prohibited: 2 (a) ii) 4. Noise generated by amplifiers at entertainment venues having a capacity of 1,000 or more persons. 5. Noise generated by any governmental body, its employee/agents, and/or its contractors in the performance of a governmental function. 6. Noise generated by airport, railway and other mass transit vehicular transportation. 7. Noise produced by gas drilling and production, as regulated by the City Code. Sec Enforcement.

11 The provisions of this section shall be enforced primarily by the Police Department and Code Enforcement Officials. Sec Savings. The repeal of any ordinance or part of ordinances effectuated by the enactment of this ordinance shall not be construed as abandoning any action now pending under or by virtue of such ordinance or as discontinuing, abating, modifying or altering any penalty accruing or to accrue, or as affecting any rights of the City under any section or provisions of any ordinances at the time of passage of this ordinance. Sec Severability. If any provision, section, sentence, clause or phrase of this ordinance, or the application of the same to any person or set of circumstances is for any reason held to be unconstitutional, void, invalid, or unenforceable, the validity of the remaining portions of this ordinance or its application to other persons or sets of circumstances shall not be affected thereby, it being the intent of the City Council of the City of Mineral Wells in adopting, and of the Mayor in approving this ordinance, that no portion thereof or provision or regulation contained herein shall become inoperative or fail by reason of any unconstitutionality or invalidity of any portion, provision or regulation. Sec Penalties. 1. A person commits an offense if the person makes noise in violation of this Section. 2. An offense under this Section is punishable by a fine of not more than Five Hundred Dollars ($500.00).

12 3. Each occurrence of a violation, or, in the case of multiple violations, each day a violation occurs or continues, constitutes a separate offense and may be punished separately. 4. A violation of this Section is a nuisance. The prosecution of an offense under this Section does not limit the City or an individual s right to seek abatement of the nuisance, including the use of injunctive or other civil relief. Sec Effective date. This ordinance shall take effect immediately from and after its passage and publication as may be required by governing law.

13 Sound Measurements - Fuzzy's Taco Shop at 306 N. Oak Street (04/06/12 to 05/09/12) db (decibel) Levels - A Weighted LEGEND State Noise limit (85 dba): 20 Proposed max thresholds 7:00 AM to 10:00 PM (75 dba) : 10:00 PM to 7:00 AM (65 dba) : Live Band on patio (exclude): 0 10:45 PM 11:30 PM 8:38 PM 9:49 PM 10:00 PM 9:30 PM 11:00 PM 11:40 PM 10:14 PM 9:20 PM 10:18 PM 10:17 PM 10:30 PM 11:05 PM 11:30 PM 8:00 PM FRI FRI WED WED WED THU FRI FRI SAT TUE TUE WED FRI FRI SAT WED 4/6/12 4/6/12 4/11/12 4/11/12 4/11/12 4/12/12 4/13/12 4/13/12 4/14/12 4/17/12 4/17/12 4/18/12 4/20/12 4/20/12 5/5/12 5/9/12 PEAK OUTSIDE (dba) PEAK PATIO (dba) PEAK ALLEY (dba)

14 Ambient Sound Pressure Measurements at 300 N. Oak Avenue 6:55 PM :20 AM :31 PM AMBIENT SIDEWALK (dba) AMBIENT ALLEYWAY (dba) 4:30 AM 11:40 PM TIME AMBIENT SIDEWALK (dba) AMBIENT ALLEYWAY (dba) 6:55 PM :31 PM :40 PM :30 AM :20 AM 58 57

15 Sound Measurement Points for Fuzzy s Taco Shop at 306 N. Oak Street Outside Front Door (public easement) Adjoining Property Line (alleyway) Outdoor Patio Area (business property)

16 Texas Municipal Code of Ordinances (Reference Group Sample) El Paso (No Friday/Saturday Extension) San Antonio (Friday/Saturday: Extended to 11:00 p.m.) Corpus Christi (Friday/Saturday: Extended by 1 hour both time ends) Fort Worth (Friday/Saturday: Extended until 2:00 a.m. in CBD and Cultural) Noise Zone All single, double and multiplefamily residential structures or property. All commercial properties. All manufacturing or industrial properties. Noise Zone All residential zoned property. All business zoned property. All industrial zoned property. Time Interval 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. Time Interval 10:00 p.m. to 600 a.m. 6:00 a.m. to 10:00 p m. 10:00 p.m. to 6:00 a.m. 6:00 a.m. to 10:00 p m. 10:00 p.m. to 6:00 a.m. 6:00 a.m. to 10:00 p m. Allowable Exterior Noise Level 50 db(a) 55 db(a) 60 db(a) 65 db(a) 65 db(a) 70 db(a) Allowable Exterior Noise Level 50 db(a) 63 db(a) 60 db(a) 70 db(a) 65 db(a) 72 db(a) Entertainment zoned property. 6:00 a.m. to 10:00 p.m. 85 db(a) Noise Zone All residential, commercial, and industrial; except entertainment. Time Interval 11:01 p.m. to 8:00 a.m. 8:01 a.m. to 11:00 p.m. Allowable Exterior Noise Level 60 db(a) 70 db(a) Entertainment district. All times 85 db(a) Noise Zone All one, two and multiplefamily districts. All non-residential and mixeduse districts. Central business and Cultural districts. Time Interval 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. Allowable Exterior Noise Level 60 db(a) 70 db(a) 70 db(a) 80 db(a) 70 db(a) 80 db(a) All other areas where existing ambient exceeds MAX All times db(a) + 3dB(A)

17 Texas Municipal Code of Ordinances (Reference Group Sample) North Richland Hills (No Friday/Saturday Extension) Terrell (No Friday/Saturday Extension) Waco (No Friday/Saturday Extension) Marble Falls (Friday/Saturday: Extended until 12:00 Midnight) Noise Zone All residential districts. All non-residential, industrial, and mixed-use districts. All property. Noise Zone Noise Zone All residential property. Time Interval 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. Time Interval 10:00 p.m. to 600 a.m. 6:00 a.m. to 10:00 p m. Time Interval 10:00 p.m. to 7:00 a.m. 7:00 a.m. to 10:00 p m. Allowable Exterior Noise Level 60 db(a) 75 db(a) 70 db(a) 80 db(a) Allowable Exterior Noise Level 85 db(a) No restrictions Allowable Exterior Noise Level 80 db(a) 85 db(a) All non-residential property. All times 85 db(a) Noise Zone All property areas. Time Interval 11:00 p.m. to 6:00 a.m. 6:00 a.m. to 11:00 p m. Allowable Exterior Noise Level 70 db(a) 80 db(a)

18 FUNDAMENTALS OF ENVIRONMENTAL ACOUSTICS Noise may be defined as unwanted sound. Noise is usually objectionable because it is disturbing or annoying. The objectionable nature of sound could be caused by its pitch or its loudness. Pitch is the height or depth of a tone or sound, depending on the relative rapidity (frequency) of the vibrations by which it is produced. Higher pitched signals sound louder to humans than sounds with a lower pitch. Loudness is intensity of sound waves combined with the reception characteristics of the ear. Intensity may be compared with the height of an ocean wave in that it is a measure of the amplitude of the sound wave. In addition to the concepts of pitch and loudness, there are several noise measurement scales that are used to describe noise in a particular location. A decibel (db) is a unit of measurement that indicates the relative amplitude of a sound. The zero on the decibel scale is based on the lowest sound level that the healthy, unimpaired human ear can detect. Sound levels in decibels are calculated on a logarithmic basis. An increase of 10 decibels represents a ten-fold increase in acoustic energy, while 20 decibels is 100 times more intense, 30 decibels is 1,000 times more intense, etc. There is a relationship between the subjective noisiness or loudness of a sound and its intensity. Each 10-decibel increase in sound level is perceived as approximately a doubling of loudness over a fairly wide range of intensities. Some of the technical terms are defined in Table 1. There are several methods of characterizing sound. The most commonly accepted and utilized by municipalities is the A-weighted sound level or dba. This scale gives greater weight to the frequencies of sound to which the human ear is most sensitive. Representative outdoor and indoor noise levels for a variety of common sound, represented in units of dba, are shown in Table 2. Because sound levels can vary markedly over a short period of time, a method for describing either the average character of the sound or the statistical behavior of the variations must be utilized. Most commonly, environmental sounds are described in terms of an average level that has the same acoustical energy as the summation of all the time-varying events. This energy equivalent sound/noise descriptor is called Leq. The most common averaging period is hourly, but Leq can describe any series of noise events of arbitrary duration. The scientific instrument used to measure noise is the sound level meter. Sound level meters can accurately measure environmental noise levels to within about plus or minus 1 dba. Various computer models are used to predict environmental noise levels from sources, such as roadways and airports. The accuracy of the predicted models depends upon the distance the receptor is from the noise source. Close to the noise source, the models are accurate to within about plus or minus 1 to 2 dba. Sensitivity to noise also increases during the evening and at night -- because excessive noise interferes with the ability to sleep. The Community Noise Equivalent Level, CNEL, is a measure of the cumulative noise exposure in a community, with a 5 db penalty added to evening (7:00 pm - 10:00 pm) and a 10 db addition to nocturnal (10:00 pm - 7:00 am) noise levels. The Day/Night Average Sound Level, Ldn, is essentially the same as CNEL, with the exception that the evening time period is dropped and all occurrences during this three-hour period are grouped into the daytime period.

19 TABLE 1: DEFINITIONS OF ACOUSTICAL TERMS Term Decibel, db Sound Pressure Level Frequency, Hz A-Weighted Sound Level, dba Equivalent Noise Level, Leq Day-Night Level, Ldn Community Noise Exposure Level, CNEL Ambient Noise Level Intrusive Definitions A unit describing the amplitude of sound, equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to the reference pressure. The reference pressure for air is 20. Sound pressure is the sound force per unit area, usually expressed in micro Pascals (or 20 micro Newtons per square meter), where 1 Pascal is the pressure resulting from a force of 1 Newton exerted over an area of 1 square meter. The sound pressure level is expressed in decibels as 20 times the logarithm to the base 10 of the ratio between the pressures exerted by the sound to a reference sound pressure (e.g., 20 micro Pascals). Sound pressure level is the quantity that is directly measured by a sound level meter. The number of complete pressure fluctuations per second above and below atmospheric pressure. Normal human hearing is between 20 Hz and 20,000 Hz. Infrasonic sound are below 20 Hz and Ultrasonic sounds are above 20,000 Hz. The sound pressure level in decibels as measured on a sound level meter using the A-weighting filter network. The A-weighting filter deemphasizes the very low and very high frequency components of the sound in a manner similar to the frequency response of the human ear and correlates well with subjective reactions to noise. The average A-weighted noise level during the measurement period. The hourly Leq used for this report is denoted as dba Leq[h]. Ldn is the equivalent noise level for a continuous 24-hour period with a 10-decibel penalty imposed during nighttime and morning hours (10:00 pm to 7:00 am). CNEL is the equivalent noise level for a continuous 24-hour period with a 5-decibel penalty imposed in the evening (7:00 pm to 10:00 pm) and a 10-decibel penalty imposed during nighttime and morning hours (10:00 pm to 7:00am) The composite of noise from all sources near and far. The normal or existing level of environmental noise at a given location. That noise which intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, and time of occurrence and tonal or informational content as well as the prevailing ambient noise level.

20 TABLE 2: TYPICAL NOISE LEVELS IN THE ENVIRONMENT Common Outdoor Noise Source Noise Level (dba) Common Indoor Noise Source Jet fly-over at 1000 feet Rock concert 120 dba 110 dba Jackhammer at 60 feet 100 dba 90 dba Night club with live music Large truck pass by at 45 feet 80 dba Noisy restaurant Garbage disposal at 3 feet Gas lawn mower at 30 feet 70 dba Vacuum cleaner at 6 feet Commercial/Urban area (daytime) Suburban expressway at 250 feet 60 dba Normal speech at 3 feet Suburban daytime Active office environment 50 dba Urban area nighttime Quiet office environment 40 dba Suburban nighttime Quiet rural areas 30 dba Library Quiet bedroom at night Wilderness area 20 dba Quiet recording studio Threshold of human hearing 10 dba 0 dba Threshold of human hearing

21 Effects of Noise Sleep and Speech Interference: The thresholds for speech interference indoors are about 45 dba if the noise is steady and above 55 dba if the noise is fluctuating. Outdoors the thresholds are about 15 dba higher. Steady noise of sufficient intensity; above 35 dba, and fluctuating noise levels above about 45 dba have been shown to affect sleep. Interior residential standards for residential dwellings are generally recommended by HUD to be at 45 dba Ldn. Typically, the highest steady traffic noise level during the daytime is about equal to the Ldn and nighttime levels are 10 dba lower. The standard is designed for sleep and speech protection and most jurisdictions apply the same criterion for all residential uses. Typical structural attenuation is dba with open windows. With closed windows in good condition, the noise attenuation factor is around 20 dba for an older structure and 25 dba for a newer dwelling. Sleep and speech interference is therefore possible when exterior noise levels are about dba Ldn with open windows and dba Ldn if the windows are closed. Levels of dba are common along collector streets and secondary arterials, while dba is a typical value for a primary/major arterial. Levels of dba are normal noise levels at the first row of development outside a freeway right-of-way. In order to achieve an acceptable interior noise environment, bedrooms facing secondary roadways need to be able to have their windows closed, those facing major roadways and freeways typically need special glass windows. Annoyance: Attitude surveys are used for measuring the annoyance felt in a community for noises intruding into homes or affecting outdoor activity areas. In these surveys, it was determined that the causes for annoyance include interference with speech, radio and television, house vibrations, and interference with sleep and rest. The Ldn as a measure of noise has been found to provide a valid correlation of noise level and the percentage of people annoyed. People have been asked to judge the annoyance caused by aircraft noise and ground transportation noise. There continues to be disagreement about the relative annoyance of these different sources. When measuring the percentage of the population highly annoyed, the threshold for ground vehicle noise is about 55 dba Ldn. At an Ldn of about 60 dba, approximately 2 percent of the population is highly annoyed. When the Ldn increases to 70 dba, the percentage of the population highly annoyed increases to about 12 percent of the population. There is, therefore, an increase of about 1 percent per dba between an Ldn of dba. Between an Ldn of dba, each decibel increase increases by about 2 percent the percentage of the population highly annoyed. People appear to respond more adversely to aircraft noise. When the Ldn is 60 dba, approximately 10 percent of the population is believed to be highly annoyed. Each decibel increase to 70 dba adds about 2 percentage points to the number of people highly annoyed. Above 70 dba, each decibel increase results in about a 3 percent increase in the percentage of the population highly annoyed. Source: Cowan, James P. Handbook of Environmental Acoustics. Van Nostrand Reinhold, New York, Egan, M. David, Architectural Acoustics. McGraw-Hill Book Company, 1988.