aci Acoustical Consultants Inc. 5031 – 210 Street Edmonton, Alberta, Canada T6M 0A8 Phone: (780) 499-1591 www.aciacoustical.com
Environmental Noise Impact Assessment For the
Proposed Pinnacle Village Residential Development
Prepared for:
Pinnacorp Investments Inc.
11/29/2024
11/29/2023 Prepared by: P. Froment, B.Sc., B.Ed., P.L.(Eng.) aci Acoustical Consultants Inc. Edmonton, Alberta APEGA Permit to Practice #P7735
aci Project #: 22-057 November 29, 2024
Disclaimer This report has been prepared by aci Acoustical Consultants Inc. (aci) in response to a specific request for service from, and for the exclusive use of, the Client to whom the report is addressed. The report has been prepared in a manner consistent with a level of care and skill ordinarily exercised by members of the engineering and science professions currently practising under similar conditions in the jurisdiction in which the services are provided, subject to the time limits and physical constraints applicable to this report. The findings contained in this report are based, in part, upon information provided by others. aci does not vouch for the accuracy of information provided by others or how that may impact the accuracy of the results presented in the report. The information contained in this report is not intended for use of, nor is it intended to be relied upon, by any person, firm, or corporation other than the Client to whom it is addressed, with the exception of the applicable regulatory authority to whom this document may be submitted. Any, calculation methods and noise models prepared by aci are considered proprietary professional work product and shall remain the copyright property of aci who authorizes only the Client to use and make copies of the report.
The report is of a summary nature and is not intended to stand alone without reference to the instructions given to aci by the Client, communications between aci and the Client, and to any other reports prepared by aci for the Client relative to the specific project described in the report. In order to properly understand the suggestions, recommendations, and opinions expressed in this report, reference must be made to the whole of the report. aci cannot be responsible for use of portions of the report without reference to the entire report. aci accepts no liability or responsibility for any damages that may be suffered or incurred by any third party as a result of the use of, reliance on, or any decision made based on this report.
Unless otherwise stated, the suggestions, recommendations, and opinions given in this report are intended only for guidance of the Client in the design of the specific project. The extent and detail of investigations, necessary to determine all of the relevant conditions which may affect potential project construction costs would normally be greater than has been carried out for design purposes. Any Contractors bidding on, or undertaking work discussed in this report, should rely on their own investigations, as well as their own interpretations of the factual data presented in the report, including but not limited to proposed construction techniques, materials selected, schedule, safety, and equipment capabilities.
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Executive Summary
aci Acoustical Consultants Inc. (aci) was retained by Pinnacorp Investments Inc c/o Arcadis to conduct an environmental noise impact assessment (NIA) for the proposed Pinnacle Village residential development (the Development) in Sturgeon County, AB. The purpose of the work was to generate a computer noise model with the proposed Development, elevation contours, road alignments, and future traffic data to determine the noise levels for residential receptors most impacted by Starkey Road & Trestle Ridge Road. This was then used to determine the noise attenuation measures required to meet Sturgeon County’s criteria for Noise Attenuation policy TRA-NAT-1.
The Future Case noise modelling scenario indicated noise levels ranging from 51.2 –58.7 dBA Leq24. Since all residential receptor Leq24 noise levels are projected to be below 65 dBA under Future Case conditions noise mitigation will not be required to meet the requirements of Sturgeon County’s Noise Attenuation policy TRA-NAT-1.
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Pinnacorp – Pinnacle Village – NIA Table of Contents 1.0
Introduction ..................................................................................................................................... 1
2.0
Location Description ....................................................................................................................... 1
3.0
Modeling Methods .......................................................................................................................... 1
3.1.
Computer Noise Modeling .......................................................................................................... 1
3.2.
Noise Modeling Scenarios........................................................................................................... 2
3.3.
Noise Modeling Parameters ........................................................................................................ 2
3.4.
Modeling Confidence .................................................................................................................. 3
4.0
Permissible Sound Levels ............................................................................................................... 4
5.0
Results and Discussion .................................................................................................................... 5
5.1.
Future Case .................................................................................................................................. 5
6.0
Conclusion ....................................................................................................................................... 6
7.0
References ....................................................................................................................................... 7
Appendix I NOISE MODELING PARAMETERS ............................................................................... 10 Appendix II THE ASSESSMENT OF ENVIRONMENTAL NOISE (GENERAL) ............................ 11 Appendix III SOUND LEVELS OF FAMILIAR NOISE SOURCES .................................................. 23
List of Tables Table 1. Future Case Noise Modeling Results ........................................................................................... 5
List of Figures Figure 1. Study Area .................................................................................................................................. 8 Figure 2. Future Case Leq24 Noise Levels .................................................................................................. 9
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Pinnacorp – Pinnacle Village – NIA 1.0 Introduction
aci Acoustical Consultants Inc. (aci) was retained by Pinnacorp Investments Inc c/o Arcadis Professional Services (Canada) Inc. (Arcadis) to conduct an environmental noise impact assessment (NIA) for the proposed Pinnacle Village residential development (the Development) in Sturgeon County, AB. The purpose of the work was to generate a computer noise model with the proposed Development, elevation contours, road alignments, and future traffic data to determine the noise levels for residential receptors most impacted by Starkey Road & Trestle Ridge Road. This was then used to determine the noise attenuation measures required to meet Sturgeon County’s criteria for Noise Attenuation policy TRA-NAT-1. 2.0 Location Description The proposed Development is in Sturgeon County, as shown in Figure 1. The study area will be bound on the south by the future Trestle Ridge Road, on the west by Starkey Road and on the north & east by open fields. As previously mentioned, Starkey Road is located immediately west of the Development and is anticipated to be the dominant noise source when the Development is completed. The area being specifically investigated for this NIA is comprised of single-family dwellings with private back yards backing directly onto Starkey Road and/or Trestle Ridge Road. As directed by Sturgeon County, a noise attenuation fence will be required along Starkey Road. As such, within the noise model, a 1.8 m tall noise barrier was placed along the rear property lines for residential lots adjacent to Starkey Road. Topographically the land between Starkey Road and the residential lots will be relatively flat with a slight decrease from the road to the lots. Currently there are no existing residences in any parts of the study area. Additionally, the land is not covered with any type of significant vegetation and once the development is in place, much of the land will be comprised of roads, structures, etc. 3.0 Modeling Methods 3.1. Computer Noise Modeling The computer noise modeling was conducted using the CADNA/A (Version 2024 MR1, build: 205.5427) software package. CADNA/A allows for the modeling of various noise sources such as road, rail, and various stationary sources. In addition, topographical features such as land contours, vegetation, and
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bodies of water can be included. Finally, meteorological conditions such as temperature, relative humidity, wind-speed and wind-direction can be included in the calculations. The calculation method used for noise propagation follows the ISO standard 9613-2. All receiver locations were assumed as being downwind from the source(s). In particular, as stated in Section 5 of the ISO document: “Downwind propagation conditions for the method specified in this part of IS0 9613 are as specified in 5.4.3.3 of IS0 1996-2:1987, namely -
-
wind direction within an angle of ± 450 of the direction connecting the centre of the dominant sound source and the centre of the specified receiver region, with the wind blowing from source to receiver, and wind speed between approximately 1 m/s and 5 m/s, measured at a height of 3 m to 11 m above the ground.
The equations for calculating the average downwind sound pressure level LAT(DW) in this part of IS0 9613, including the equations for attenuation given in clause 7, are the average for meteorological conditions within these limits. The term average here means the average over a short time interval, as defined in 3.1. These equations also hold, equivalently, for average propagation under a well-developed moderate ground-based temperature inversion, such as commonly occurs on clear, calm nights”. 3.2. Noise Modeling Scenarios As part of the study, the following scenario was modeled: 1) Future Case: This included the future conditions with the proposed residential development, future traffic volumes (2044 Horizon) and alignments for Starkey Road and Trestle Ridge Road. 3.3. Noise Modeling Parameters Due to the relatively short distances from the roads to the nearest residential structures and the minimal amount of vegetation, vegetative sound absorption was not included in the model. In addition, snow cover was not included since there can be variation in absorption/reflection caused by different snow conditions. As a result, all projected future sound level propagation calculations are considered representative of summertime conditions for all residents.
Buildings were included in the model for a residential lot, however, the exact dimensions and locations of future structures were not known, so approximate dimensions were used.
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Digital topographical
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information representing future elevation contours for the Development were included in the noise model and were provided by Arcadis. Traffic volumes for the study area were reflective of the 2044 horizon and were obtained from the Transportation Impact Assessment (TIA) entitled, “Pinnacle Village Outline Plan TIA” by Arcadis (2024).
The computer noise modeling results were calculated in two ways. First, sound levels were calculated at specific receptor locations directly adjacent to the major roadways (i.e. within typical residential outdoor amenity spaces). This was done at a height of 1.5 m (from the ground) and at an offset from the backproperty line of 10 m for all locations 1. The projected noise levels at the receptor locations provide a more representative indication of the typical noise levels experienced by residents in their private backyard spaces (i.e., not directly adjacent to the rear property line). In addition, the use of specific receptor locations allows for a better evaluation of the anticipated performance of any noise mitigation measures (i.e., the reduction in noise levels), if required. Secondly, color noise contours were calculated using a 3 m x 3 m grid over the entire study area at a height of 1.5 m. The color noise contours are used to determine if and where noise mitigation is required as they illustrate the projected noise levels within the entire residential private back yard spaces. Additionally, they provide the general noise levels of all residential locations within the entire study area that would otherwise be impracticable to be provided. Refer to Appendix I for a list of the noise modeling parameters. 3.4. Modeling Confidence The algorithms used for the noise modeling follow the ISO 9613 standard. The published accuracy for this standard is ±3 dBA between 100 m – 1,000 m. Accuracy levels beyond 1,000 m are not published. Experience based on similar noise models conducted over large distances shows that, as expected, as the distance increases, the associated accuracy in prediction decreases.
Experience has shown that
environmental factors such as wind, temperature inversions, topography and ground cover all have increasing effects over distances larger than approximately 1,500 m. As such, since all receptors are within approximately 1,500 m of the various noise sources, the prediction confidence is considered high.
1
Consistent with industry standards and most likely reflective of the required 5m from the nearest dwelling’s façade, as per TRA-NAT-1.
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Environmental noise levels from roads are commonly described in terms of equivalent sound levels or Leq. This is the level of a steady sound having the same acoustic energy, over a given time period, as the fluctuating sound. In addition, this energy averaged level is A–weighted to account for the reduced sensitivity of average human hearing to low frequency sounds. These Leq in dBA, which are the most common environmental noise measure, are often given for daytime (07:00 to 22:00) LeqDay and nighttime (22:00 to 07:00) LeqNight while other criteria use the entire 24-hour period as Leq24. Refer to Appendix II for a description of the acoustical terminology and Appendix III for a list of common noise sources.
The criteria used to evaluate the road noise in the study area include Sturgeon County’s Noise Attenuation policy TRA-NAT-1. The following is taken directly from Sturgeon County:
Policy Statement:
Sturgeon County will consider attenuation mitigation measures for actual traffic noise in residential neighborhoods when measured noise levels 5 meters from the nearest dwelling’s façade and 1.5 meters above ground elevation at the point, exceeds 65 dBA*. * - Sound level descriptor to be used in all assessment will be the 24-Hour Energy Equivalent Sound Level or Leq (24 Hour) expressed in A-weighted decibels or dBA.
In summary, the TRA-NAT-1 states that noise attenuation mitigation measures when noise levels exceed of 65 dBA Leq24 in residential neighbourhood. As such, the permissible sound level (PSL) for the area is 65 dBA Leq24. As previously mentioned, as directed by Sturgeon County, a 1.8 m tall noise barrier was placed along the rear property lines for residential lots adjacent to Starkey Road.
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The results of the Future Case noise modeling at various residential outdoor amenity spaces are provided in Table 1 and illustrated in Figure 2. Table 1. Future Case Noise Modeling Results Receptor
Leq24 (dBA)
Receptor
Leq24 (dBA)
R-01
53.2
R-14
56.9
R-02
56.5
R-15
57.0
R-03
57.2
R-16
57.1
R-04
56.9
R-17
56.9
R-05
56.8
R-18
56.7
R-06
55.2
R-19
56.3
R-07
58.7
R-20
56.6
R-08
57.5
R-21
56.4
R-09
56.1
R-22
56.4
R-10
57.7
R-23
56.3
R-11
57.4
R-24
56.3
R-12
57.1
R-25
55.3
R-13
57.2
R-26
51.2
Minimum
51.2
Maximum
58.7
The results of the Future Case modeling indicate noise levels ranging from 51.2 – 58.7 dBA Leq24. As anticipated, the highest projected noise levels in the Study Area are for the western residents, since these residents are within closest proximity to Starkey Road, which has the highest projected noise levels. Since all residential receptor Leq24 noise levels are projected to be well below 65 dBA under Future Case conditions, noise mitigation (beyond the 1.8 m barrier) will not be required to meet the requirements of Sturgeon County’s Noise Attenuation policy TRA-NAT-1.
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Pinnacorp – Pinnacle Village – NIA 6.0 Conclusion
The Future Case noise modelling scenario indicated noise levels ranging from 51.2 –58.7 dBA Leq24. Since all residential receptor Leq24 noise levels are projected to be below 65 dBA under Future Case conditions noise mitigation will not be required to meet the requirements of Sturgeon County’s Noise Attenuation policy TRA-NAT-1.
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Pinnacorp – Pinnacle Village – NIA 7.0 References -
Sturgeon County’s Noise Attenuation policy TRA-NAT-1, January (2010)
-
Pinnacle Village Outline Plan Transportation Impact Assessment, by Arcadis (November 2024)
-
International Organization for Standardization (ISO), Standard 1996-1, Acoustics – Description, measurement and assessment of environmental noise – Part 1: Basic quantities and assessment procedures, 2003, Geneva Switzerland.
-
International Organization for Standardization (ISO), Standard 9613-1, Acoustics – Attenuation of sound during propagation outdoors – Part 1: Calculation of absorption of sound by the atmosphere, 1993, Geneva Switzerland.
-
International Organization for Standardization (ISO), Standard 9613-2, Acoustics – Attenuation of sound during propagation outdoors – Part 2: General method of calculation, 1996, Geneva Switzerland.
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Outline of Study Area
Figure 1. Study Area
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Pinnacorp – Pinnacle Village – NIA Outline of Study Area
1.8 m Tall Barrier
R-01
R-05
R-10
R-15
R-26
R-20
Starkey Road Pinnacle Way
Figure 2. Future Case Leq24 Noise Levels
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Trestle Ridge Road
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Appendix I NOISE MODELING PARAMETERS Day (Vehicles Per Hour)
Day % Heavy Vehicles
Night (Vehicles Per Hour)
Night % Heavy Vehicles
Speed (km/hr)
Total Volume (vehicles per day)
Starkey Road (North of Trestle Ridge Road)
415
5
76
5
70
6910
Starkey Road (North of Trestle Ridge Road)
761
5
139
5
70
12680
Trestle Ridge Road (West of Pinnacle Way)
275
3
50
3
60
4580
Trestle Ridge Road (East of Pinnacle Way)
181
3
34
3
60
3015
East Estates Way
224
3
41
3
60
3730
Pinnacle Way
85
2
16
2
50
1420
Residential Streets
12
3
5
2
50
225
Road
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Appendix II THE ASSESSMENT OF ENVIRONMENTAL NOISE (GENERAL) Sound Pressure Level Sound pressure is initially measured in Pascal’s (Pa). Humans can hear several orders of magnitude in sound pressure levels, so a more convenient scale is used. This scale is known as the decibel (dB) scale, named after Alexander Graham Bell (telephone guy). It is a base 10 logarithmic scale. When we measure pressure we typically measure the RMS sound pressure. 2 PRMS P SPL = 10 log10 2 = 20 log10 RMS Pref Pref
Where:
SPL = Sound Pressure Level in dB PRMS = Root Mean Square measured pressure (Pa) Pref = Reference sound pressure level (Pref = 2x10-5 Pa = 20 µPa)
This reference sound pressure level is an internationally agreed upon value. It represents the threshold of human hearing for “typical” people based on numerous testing. It is possible to have a threshold which is lower than 20 µPa which will result in negative dB levels. As such, zero dB does not mean there is no sound! In general, a difference of 1 – 2 dB is the threshold for humans to notice that there has been a change in sound level. A difference of 3 dB (factor of 2 in acoustical energy) is perceptible and a change of 5 dB is strongly perceptible. A change of 10 dB is typically considered a factor of 2. This is quite remarkable when considering that 10 dB is 10-times the acoustical energy!
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The range of frequencies audible to the human ear ranges from approximately 20 Hz to 20 kHz. Within this range, the human ear does not hear equally at all frequencies. It is not very sensitive to low frequency sounds, is very sensitive to mid frequency sounds and is slightly less sensitive to high frequency sounds. Due to the large frequency range of human hearing, the entire spectrum is often divided into 31 bands, each known as a 1/3 octave band. The internationally agreed upon center frequencies and upper and lower band limits for the 1/1 (whole octave) and 1/3 octave bands are as follows:
Lower Band Limit 11
Whole Octave Center Frequency 16
Upper Band Limit 22
22
31.5
44
44
63
88
88
125
177
177
250
355
355
500
710
710
1000
1420
1420
2000
2840
2840
4000
5680
5680
8000
11360
11360
16000
22720
Lower Band Limit 14.1 17.8 22.4 28.2 35.5 44.7 56.2 70.8 89.1 112 141 178 224 282 355 447 562 708 891 1122 1413 1778 2239 2818 3548 4467 5623 7079 8913 11220 14130 17780
13
1/3 Octave Center Frequency 16 20 25 31.5 40 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 6300 8000 10000 12500 16000 20000
Upper Band Limit 17.8 22.4 28.2 35.5 44.7 56.2 70.8 89.1 112 141 178 224 282 355 447 562 708 891 1122 1413 1778 2239 2818 3548 4467 5623 7079 8913 11220 14130 17780 22390
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Human hearing is most sensitive at approximately 3500 Hz which corresponds to the ¼ wavelength of the ear canal (approximately 2.5 cm). Because of this range of sensitivity to various frequencies, we typically apply various weighting networks to the broadband measured sound to more appropriately account for the way humans hear. By default, the most common weighting network used is the so-called “A-weighting”. It can be seen in the figure that the low frequency sounds are reduced significantly with the A-weighting.
Combination of Sounds When combining multiple sound sources the general equation is:
n SPL i Σ SPL n = 10 log 10 Σ 10 10 i =1 Examples: - Two sources of 50 dB each add together to result in 53 dB. - Three sources of 50 dB each add together to result in 55 dB. - Ten sources of 50 dB each add together to result in 60 dB. - One source of 50 dB added to another source of 40 dB results in 50.4 dB It can be seen that, if multiple similar sources exist, removing or reducing only one source will have little effect.
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Over the years a number of methods for measuring and describing environmental noise have been developed. The most widely used and accepted is the concept of the Energy Equivalent Sound Level (Leq) which was developed in the US (1970’s) to characterize noise levels near US Air-force bases. This is the level of a steady state sound which, for a given period of time, would contain the same energy as the time varying sound. The concept is that the same amount of annoyance occurs from a sound having a high level for a short period of time as from a sound at a lower level for a longer period of time. The Leq is defined as:
1 T P 2 1 T dB 10 L eq = 10 log 10 ∫ 10 dT = 10 log 10 ∫ dT 2 0 T 0 Pref T We must specify the time period over which to measure the sound. i.e. 1-second, 10-seconds, 15-seconds, 1-minute, 1-day, etc. An Leq is meaningless if there is no time period associated.
In general there a few very common Leq sample durations which are used in describing environmental noise measurements. These include: -
Leq24 LeqNight LeqDay LDN
- Measured over a 24-hour period - Measured over the night-time (typically 22:00 – 07:00) - Measured over the day-time (typically 07:00 – 22:00) - Same as Leq24 with a 10 dB penalty added to the night-time
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Another method of conveying long term noise levels utilizes statistical descriptors. These are calculated from a cumulative distribution of the sound levels over the entire measurement duration and then determining the sound level at xx % of the time.
Industrial Noise Control, Lewis Bell, Marcel Dekker, Inc. 1994
The most common statistical descriptors are: Lmin L01 L10
L50 L90 L99 Lmax
- minimum sound level measured - sound level that was exceeded only 1% of the time - sound level that was exceeded only 10% of the time. - Good measure of intermittent or intrusive noise - Good measure of Traffic Noise - sound level that was exceeded 50% of the time (arithmetic average) - Good to compare to Leq to determine steadiness of noise - sound level that was exceeded 90% of the time - Good indicator of typical “ambient” noise levels - sound level that was exceeded 99% of the time - maximum sound level measured
These descriptors can be used to provide a more detailed analysis of the varying noise climate: - If there is a large difference between the Leq and the L50 (Leq can never be any lower than the L50) then it can be surmised that one or more short duration, high level sound(s) occurred during the time period. - If the gap between the L10 and L90 is relatively small (less than 15 – 20 dBA) then it can be surmised that the noise climate was relatively steady.
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In order to understand sound propagation, the nature of the source must first be discussed. In general, there are three types of sources. These are known as ‘point’, ‘line’, and ‘area’. This discussion will concentrate on point and line sources since area sources are much more complex and can usually be approximated by point sources at large distances. Point Source As sound radiates from a point source, it dissipates through geometric spreading. The basic relationship between the sound levels at two distances from a point source is:
r2 ∴ SPL1 − SPL 2 = 20 log 10 r1 Where:
SPL1 = sound pressure level at location 1, SPL2 = sound pressure level at location 2 r1 = distance from source to location 1, r2 = distance from source to location 2
Thus, the reduction in sound pressure level for a point source radiating in a free field is 6 dB per doubling of distance. This relationship is independent of reflectivity factors provided they are always present. Note that this only considers geometric spreading and does not take into account atmospheric effects. Point sources still have some physical dimension associated with them, and typically do not radiate sound equally in all directions in all frequencies. The directionality of a source is also highly dependent on frequency. As frequency increases, directionality increases. Examples (note no atmospheric absorption): - A point source measuring 50 dB at 100m will be 44 dB at 200m. - A point source measuring 50 dB at 100m will be 40.5 dB at 300m. - A point source measuring 50 dB at 100m will be 38 dB at 400m. - A point source measuring 50 dB at 100m will be 30 dB at 1000m. Line Source A line source is similar to a point source in that it dissipates through geometric spreading. The difference is that a line source is equivalent to a long line of many point sources. The basic relationship between the sound levels at two distances from a line source is:
r2 SPL 1 − SPL 2 = 10 log 10 r 1 The difference from the point source is that the ‘20’ term in front of the ‘log’ is now only 10. Thus, the reduction in sound pressure level for a line source radiating in a free field is 3 dB per doubling of distance. Examples (note no atmospheric absorption): - A line source measuring 50 dB at 100m will be 47 dB at 200m. - A line source measuring 50 dB at 100m will be 45 dB at 300m. - A line source measuring 50 dB at 100m will be 44 dB at 400m. - A line source measuring 50 dB at 100m will be 40 dB at 1000m.
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As sound transmits through a medium, there is an attenuation (or dissipation of acoustic energy) which can be attributed to three mechanisms: 1) Viscous Effects - Dissipation of acoustic energy due to fluid friction which results in thermodynamically irreversible propagation of sound. 2) Heat Conduction Effects - Heat transfer between high and low temperature regions in the wave which result in non-adiabatic propagation of the sound. 3) Inter Molecular Energy Interchanges - Molecular energy relaxation effects which result in a time lag between changes in translational kinetic energy and the energy associated with rotation and vibration of the molecules.
The following table illustrates the attenuation coefficient of sound at standard pressure (101.325 kPa) in units of dB/100m. Temperature
Relative Humidity
oC
(%)
125
250
500
1000
2000
4000
20
0.06
0.18
0.37
0.64
1.40
4.40
50
0.03
0.10
0.33
0.75
1.30
2.50
90
0.02
0.06
0.24
0.70
1.50
2.60
20
0.07
0.15
0.27
0.62
1.90
6.70
50
0.04
0.12
0.28
0.50
1.00
2.80
90
0.02
0.08
0.26
0.56
0.99
2.10
20
0.06
0.11
0.29
0.94
3.20
9.00
50
0.04
0.11
0.20
0.41
1.20
4.20
90
0.03
0.10
0.21
0.38
0.81
2.50
20
0.05
0.15
0.50
1.60
3.70
5.70
50
0.04
0.08
0.19
0.60
2.10
6.70
90
0.03
0.08
0.15
0.36
1.10
4.10
30
20
10
0
-
Frequency (Hz)
As frequency increases, absorption tends to increase As Relative Humidity increases, absorption tends to decrease There is no direct relationship between absorption and temperature The net result of atmospheric absorption is to modify the sound propagation of a point source from 6 dB/doubling-of-distance to approximately 7 – 8 dB/doubling-of-distance (based on anecdotal experience)
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120
Sound Pressure Level (dB)
100
80
Base
60 1 kHz
500 Hz
250 Hz
125 Hz
1600
1800
2000
2 kHz 40 4 kHz 20 8 kHz
0
0
200
400
600
800
1000 1200 distance (m)
1400
Atmospheric Absorption at 10oC and 70% RH
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Pinnacorp – Pinnacle Village – NIA Meteorological Effects
There are many meteorological factors which can affect how sound propagates over large distances. These various phenomena must be considered when trying to determine the relative impact of a noise source either after installation or during the design stage. Wind - Can greatly alter the noise climate away from a source depending on direction - Sound levels downwind from a source can be increased due to refraction of sound back down towards the surface. This is due to the generally higher velocities as altitude increases. - Sound levels upwind from a source can be decreased due to a “bending” of the sound away from the earth’s surface. - Sound level differences of ±10dB are possible depending on severity of wind and distance from source. - Sound levels crosswind are generally not disturbed by an appreciable amount - Wind tends to generate its own noise, however, and can provide a high degree of masking relative to a noise source of particular interest. Temperature - Temperature effects can be similar to wind effects - Typically, the temperature is warmer at ground level than it is at higher elevations. - If there is a very large difference between the ground temperature (very warm) and the air aloft (only a few hundred meters) then the transmitted sound refracts upward due to the changing speed of sound. - If the air aloft is warmer than the ground temperature (known as an inversion) the resulting higher speed of sound aloft tends to refract the transmitted sound back down towards the ground. This essentially works on Snell’s law of reflection and refraction. - Temperature inversions typically happen early in the morning and are most common over large bodies of water or across river valleys. - Sound level differences of ±10dB are possible depending on gradient of temperature and distance from source. Rain - Rain does not affect sound propagation by an appreciable amount unless it is very heavy - The larger concern is the noise generated by the rain itself. A heavy rain striking the ground can cause a significant amount of highly broadband noise. The amount of noise generated is difficult to predict. - Rain can also affect the output of various noise sources such as vehicle traffic. Summary - In general, these wind and temperature effects are difficult to predict - Empirical models (based on measured data) have been generated to attempt to account for these effects. - Environmental noise measurements must be conducted with these effects in mind. Sometimes it is desired to have completely calm conditions, other times a “worst case” of downwind noise levels are desired.
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Pinnacorp – Pinnacle Village – NIA Topographical Effects
Similar to the various atmospheric effects outlined in the previous section, the effect of various geographical and vegetative factors must also be considered when examining the propagation of noise over large distances. Topography - One of the most important factors in sound propagation. - Can provide a natural barrier between source and receiver (i.e. if berm or hill in between). - Can provide a natural amplifier between source and receiver (i.e. large valley in between or hard reflective surface in between). - Must look at location of topographical features relative to source and receiver to determine importance (i.e. small berm 1km away from source and 1km away from receiver will make negligible impact). Grass - Can be an effective absorber due to large area covered - Only effective at low height above ground. Does not affect sound transmitted direct from source to receiver if there is line of sight. - Typically less absorption than atmospheric absorption when there is line of sight. - Approximate rule of thumb based on empirical data is: (dB / 100m) Ag = 18 log10 ( f ) − 31 Where: Ag is the absorption amount Trees - Provide absorption due to foliage - Deciduous trees are essentially ineffective in the winter - Absorption depends heavily on density and height of trees - No data found on absorption of various kinds of trees - Large spans of trees are required to obtain even minor amounts of sound reduction - In many cases, trees can provide an effective visual barrier, even if the noise attenuation is negligible.
Tree/Foliage attenuation from ISO 9613-2:1996
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Bodies of Water - Large bodies of water can provide the opposite effect to grass and trees. - Reflections caused by small incidence angles (grazing) can result in larger sound levels at great distances (increased reflectivity, Q). - Typically air temperatures are warmer high aloft since air temperatures near water surface tend to be more constant. Result is a high probability of temperature inversion. - Sound levels can “carry” much further. Snow - Covers the ground for approximately 1/2 of the year in northern climates. - Can act as an absorber or reflector (and varying degrees in between). - Freshly fallen snow can be quite absorptive. - Snow which has been sitting for a while and hard packed due to wind can be quite reflective. - Falling snow can be more absorptive than rain, but does not tend to produce its own noise. - Snow can cover grass which might have provided some means of absorption. - Typically sound propagates with less impedance in winter due to hard snow on ground and no foliage on trees/shrubs.
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Appendix III SOUND LEVELS OF FAMILIAR NOISE SOURCES Used with Permission Obtained from AER Guide 38: Noise Control Directive User Guide (February 2007)
Source 1 Sound Level ( dBA) ____________________________________________________________________________________ Bedroom of a country home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
Soft whisper at 1.5 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
Quiet office or living room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .
40
Moderate rainfall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
Inside average urban home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
Quiet street . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
Normal conversation at 1 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60
Noisy office . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60
Noisy restaurant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70
Highway traffic at 15 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
Loud singing at 1 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
Tractor at 15 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
78-95
Busy traffic intersection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
Electric typewriter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
Bus or heavy truck at 15 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
88-94
Jackhammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
88-98
Loud shout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
90
Freight train at 15 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
95
Modified motorcycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
95
Jet taking off at 600 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100
Amplified rock music . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
110
Jet taking off at 60 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
120
Air-raid siren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
130
1
Cottrell, Tom, 1980, Noise in Alberta, Table 1, p.8, ECA80 - 16/1B4 (Edmonton: Environment Council of Alberta).
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SOUND LEVELS GENERATED BY COMMON APPLIANCES Used with Permission Obtained from AER Guide 38: Noise Control Directive User Guide (February 2007)
Source 1 Sound level at 3 feet (dBA) ____________________________________________________________________________________ Freezer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38-45 Refrigerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34-53
Electric heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
Hair clipper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
Electric toothbrush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48-57
Humidifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41-54
Clothes dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51-65
Air conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50-67
Electric shaver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47-68
Water faucet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
62
Hair dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
58-64
Clothes washer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48-73
Dishwasher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59-71
Electric can opener . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60-70
Food mixer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59-75
Electric knife . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
65-75
Electric knife sharpener . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
Sewing machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70-74
Vacuum cleaner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
65-80
Food blender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
65-85
Coffee mill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75-79
Food waste disposer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
69-90
Edger and trimmer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
81
Home shop tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64-95
Hedge clippers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
85
Electric lawn mower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80-90
1
Reif, Z. F., and Vermeulen, P. J., 1979, “Noise from domestic appliances, construction, and industry,” Table 1, p.166, in Jones, H. W., ed., Noise in the Human Environment, vol. 2, ECA79-SP/1 (Edmonton: Environment Council of Alberta). 24
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