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HomeMy WebLinkAboutZMA202100003 Study 2021-08-164;1;<<• A C E N T E C H August 11, 2021 Charles D'Angelo Clifton Management LLC 4 Warwick Road Summit NJ 07901 cdangelo(weStmountcapltalgroup. com Subject Review of Sound Propagation from Proposed Event Site Special Event Venue, Collina Farm, Charlottesville, VA Acentech Project No. 634629, Revision 2 Dear Mr. D'Angelo: .))�(c 2150 Wise Street #5852♦♦♦-' Charlottesville, VA 22905 434 218 0759 acentech.com Thank you for taking the time to discuss your project and getting me in touch with your engineering team and the staff onsite at The Clifton. This review outlines our understanding of your project, our assumptions regarding sound source levels and placement, and details the associated modeling and prediction of sound levels throughout the site. A brief glossary is included at the end of this letter. EXECUTIVE SUMMARY Sound level predictions due to events at the new Collina Farm venue were made using measured sound levels at the current Clifton event venue as reference. The Collina Farm venue is expected to include an event structure with three walls comprised of roll -up style doors. Inside this structure the loudspeakers were placed facing West-southwest with the western and southern doors rolled up (quasi -outdoor configuration). No review has been made of amplified sound with all wall in place (indoor configuration), as the sound levels would be much lower and the county's preliminary review only asked the applicant to study outdoor amplified sound. Based on the results from this study, we expect that if the Collina Farm site is configured to meet all of our assumptions outlined in this report, the predicted sound levels will meet the county's daytime noise limits and be below 60 dBA at all property lines. However, in order to meet the nighttime noise limits at all locations the volume of amplified sound would need to be reduced by roughly 5 dBA relative to typical events at the current outdoor venue at The Clifton. Further details and analysis follow. ALBEMARLE COUNTY NOISE ORDINANCE We understand that your team has had discussions with Albemarle County staff, and you have been given direction to conduct a noise study of outdoor amplified sound at the Collina Farm event venue for inclusion with your application. As is typical for these types of projects, Albemarle County expects the noise study will acoustics av/it/security I vibration The Clifton August 11, 2021 Page 2 of 14 compare predicted sound levels due to these outdoor events with the maximum allowable sound levels 1. All of the parcels adjacent to Collina Farm are zoned rural or residential and must meet the strictest of these limits. For this type of zoning, the maximum allowable sound levels are defined as an equivalent continuous sound pressure level (LAeq — essentially an average) of 60 dBA during the daytime and 55 dBA during the nighttime Z. The Albemarle County Code includes additional details outlining the necessary equipment and measurement procedure (for existing projects), applicable definitions, and source exemptions. Relevant exemptions include transportation and a person's voice. Note that while amplified music is listed as exempt, we understand that exemption does not apply to this use. BACKGROUND In the preliminary special use permit application your team has outlined where the event structure, campsites, cabins, and bathhouse will go. Figure A shows this Collina Farm concept plan as outlined in the preliminary SUP application. Figure A: Collina Farm Concept Plan, Preliminary SUP appl 0 / / Proposed parking Y , g gravel to \\ Appmximtl<locatlonorwalkways: ��•� ~�� pedestrian paths connect parking // ♦� / to evem spar ueu e 1\ i. Existing far nhnus \� brenu, rropoua f16) SW sq. fl. <46iru or �Tng. aaea _71�'-,� Addiuono Naes. 1. pnotakiveglsmPm'ift'shall em,wanre e 10.500 fl. primitive cation, Sheet 5 CWINA FARIM �Nk FARU,CONCEPT PLAN SheeH5of6 We understand that the event structure will be enclosed, but that three of those walls may be comprised of roll - up style doors to allow the outside in, with only the north wall being fixed. Since the event venue can essentially transform into an outdoor venue, you have asked us to review the venue for compliance with the county's noise 'Albemarle County Code, Chapter 18, section 4.18.04, Noise. httos,glibrary.municode.comNa/albemarle county/codes/code of ordinances?node1d=CH18Z0 ARTIIBARE S4GERE S4.18NO S4.18.04MASOLE 2 The county defines daytime as 7AM to 1OPM and nighttime as 1OPM to 7AM. 4)11it0 ACENTECH The Clifton August 11, 2021 Page 3 of 14 ordinance limits. The major sources of sound due to events are expected to be voices from the gathered crowd and amplified speech/music. Sound Levels Measurements at The Clifton While your upcoming special use permit is looking to add the event venue at Collina Farm, we undersand that you are already operating events at The Clifton venue under a separate special use permit. This provided us with an opportunity to measure source sound levels during some of these events for use in this review of Collina Farm events. We continuously measured sound levels at The Clifton's event venue from May 25 through May 31, 2021, including two events with live bands and one with a DJ. These measurements were made approximately 90 feet from the edge of the stage using a class 1 certified sound level meter that was field calibrated at the time of install. All three events had similar A -weighted, equivalent -continuous sound levels (LAeq) with around 85 dBA at 90 feet. However, as shown in Figure B below, the DJ generated significantly more low frequency sound (bass) than the live bands did. Figure B: Measured Sound Level Spectra During Events at The Clifton Xf, m a � 80 0 v 70 a a 60 v 5 v0 J 40rtotal re bass than w 30isn't reflected dvel.Live Band (85 dBA at 90 feet) 20 010DJ (85.5 dBA at 90 feet) a w m 0 a 1 'L 3 h 4 ,y'L ,ti0 3'ti y0 �O 1.tih ��O 1/3 Octave Band Center Frequency (Hz) During the week preceding the events at The Clifton we were able to make ambient sound level measurements at two locations on the property. The first was close the edge of the Collina Farm property near the top of Hurtts Pond and the second close to the southeastern corner of The Clifton near the bottom of Hurtts Pond, as shown in Figure C. These ambient sound level measurements should help to put the sound level predictions into perspective — limiting project sound levels relative to ambient means a lower impact to the community. Table 1 shows the measured sound levels at each location for four consecutive nights, when events might typically take place. We understand that no events were taking place on these night and the ambient sound level was consistently around 47 dBA for each night at both measurment locations. The historic weather report shows that the temperatures were relatively mild, with little wind, and no precipitation. We expect the these ambient sound levels are controlled by the general hum of traffic from nearby Interstate-64 and some insect activity. 4))11tO ACENTECH The Clifton August 11, 2021 Page 4 of 14 Figure C: Ambient Sound Level Measurement Locations Fo :o -:... Richmontl Rd Rich, Location A • 11 • Location B Table 1. Ambient Sound Level Measurement Results Day and Time Measured Sound Levels, LAey Location A Location B Friday May 21, 7PM —11PM 49 dBA 48 dBA Saturday May 22, 713M —11PM 46 dBA 49 dBA Sunday May 23, 7PM —11PM 47 dBA 48 dBA Monday May 24, 713M — 1113M 49 dBA 44 dBA Energy Average of the Above Periods 48 dBA 47 dBA Given the consistency in the ambient sound levels between these two locations, which are roughly 1h mile apart, we expect these sound levels are characteristic of the ambient noise in the area surrounding the Collina Farm and Clifton properties. We also expect that ambient sound levels will be higher at properties closer to the interstate. Amplified Sound at Collina Farm In our experience amplified music and amplified speech are the loudest sources of noise at most events. We generally see that typical sound pressure levels on the edge of a dance floor are often near 85 dBA and increase to above 100 dBA as you move closer to the loudspeakers. For reference, 85 dBA is about the level of a loud film in a movie theater, while 100 dBA would be similar to a dance club or louder fitness class, but quieter than a rock concert. Note that these levels could fall in a wider range based on the performer/presenter's tastes and their client's wishes. In an effort to best represent the sound level from the types of events you will have at Collina Farm, we are able to use the sound level measurements from The Clifton events as reference. The measured 85 dBA sound 4))11tOACENTECH The Clifton August 11, 2021 Page 5 of 14 pressure levels at 90 feet from the loudspeakers equates to around 90 dBA at 50 feet 3, which is closer to the dance floor, and will be better proxy location for monitoring of sound level compliance. For our analysis, we have assumed a two -loudspeaker configuration using the measured sound level from The Clifton events. The specific music played during a given event will dictate the frequency content of the reproduced sound. For example, some music is bass heavy, while other music is not. While we cannot predict the exact music that will be played, we have assumed an energy -averaged frequency distribution measured from the two live bands. Crowd Noise at Collina Farm While a person's voice is exempt from the county's noise ordinance, it will always exist during an event. This means that it is not easy, or practical, to remove a crowd's contribution from a measured sound pressure level, making it difficult to show compliance with the noise ordinance of the non-exempt sources. Therefore, to be thorough and to best reflect the constant sources of noise heard by neighbors, we have included predicted crowd noise in our review. Crowd noise can be very difficult to predict because there are so many independent variables. In an effort to predict crowd noise we are relying on research 4 that characterizes the prediction of outdoor noise due to small to medium sized crowds. Note that very little research has been completed on larger crowds and the paper we have referenced limited their review to crowd sizes of up to only 100 people, which still makes it the best resource we have for predicting noise from crowds of this size. Following the details outlined in this paper, the crowd's equivalent continuous sound power level (LwAeq) has been predicted using the expected number of people at the event. The prediction shows that the sound level will decrease by 4.5 dBA for each halving of crowd size 5. We understand that you are requesting approval for events of up to 300 people at the Collina Farm venue, so that maximum attendance size has been used in our predictive model. The sound power level for 300 people has been added inside the event structure for our predictions at Collina Farm. Note that this crowd noise prediction is for the equivalent continuous level. However, crowd noise is transient and should be expected to be higher and lower over time, such that the actual sound levels of a crowd vary. Because the sound power level of the crowd is expected to be more than 20 dBA lower than that of the amplified sound from the PA speakers, it will contribute very little to the highest sound levels generated during an event on a longer -term LAeq basis. SOUND LEVEL MODELING We use a software package called CadnaA to build a model, predict noise levels, and present that data. CadnaA is a widely recognized and accepted noise propagation modeling software that follows ISO 9613-2 6. We were able to obtain public terrain data for the planned site and used Albemarle County GIS to identify building locations and property boundaries. Using this data, we have built a noise propagation model of your site for the purposes of sound level prediction. Propagation Model Details Buildings near sound source(s) were defined to provide reflection and shielding in the sound propagation path. Elevation contours provided the necessary topographic information to predict spreading, ground and foliage absorption, shielding, and diffraction. These physical conditions in the sound propagation path influence how 3 Resulting in a source sound Dower level (LwAQ of over 120 dBA re 1pW 4 Prediction of Noise from Small to Medium Sized Crowds. M.J. Hayne, at. al. ACOUSTICS 2011. 6 Crowd sound Dower levels are predicted to be about 101 dBA for 300 people and 96.5 dBA for 150 people. 6 International Standards Organization 9613-2, Attenuation of Sound during Propagation Outdoors. •'3,1t0 ACENTECH The Clifton August 11, 2021 Page 6 of 14 the sound is absorbed or reflected and ground conditions in particular can vary greatly for a given site. Collina Farm is largely soft ground with ground absorption factors likely nearing 1. However, in an effort to be more conservative in our predictions, we have chosen to model the general ground absorption factors as 0.5, midway between reflective (0) and absorptive (1). Additionally, much of the project boundary includes the Rivanna River and Hurtts Pond, which has been accounted for by including ground absorption factors of 0 (reflective) in those areas. Foliage such as trees and bushes were included within and outside the project boundary in appropriate regions because of the forest -like density of trees. Note that seasonal variations will occur, but the planned outdoor uses would only take place in the warmer seasons when there is little variation. Atmospheric attenuation of sound is somewhat influenced by temperature and relative humidity, but should not have a large impact on our results. This is because lower frequencies and higher frequencies do not behave the same for a given set of conditions. Because this study only reviews outdoor events at Collina Farm, we expect they will primarily be in use during fair weather, so we have assumed a typical temperature of 80OF and a relative humidity of 70%. We have not accounted for the effects of temperature inversions, wind speed, and wind direction in the sound propagation model. These variables require meteorological data specific to the site and further complicate the predictions. Note that temperature inversions, where a layer of warm air covers cooler surface air, typically occur near sunrise of clear and calm nights, when events will not be taking place. A review of typical weather conditions on Weather Spark 7 shows that the warmer months, when events are expected to be held, have an hourly mean wind speed below 4 mph (roughly 1.5 m/s), which should not be high enough to perceptibly change the downwind sound level 8. Since the applicable wind correction factor would be small and based on actual wind direction/speed, it has not been included in our model. This means that our model and predictions represent the general wind conditions expected for this region. Event Structure & Amplified Sound Sources The event structure, in its proposed operating condition, would have three walls rolled up (west, south, and east) and a standard fourth wall on the north side. However, because the nearest neighbors are to the east, and sound from unamplified instruments is more omnidirectional than the main loudspeakers, we do not recommend rolling up the east wall during the performance portion of the event. We have modeled the event structure as reflective barrier walls to the north and east, a reflective floor and a 20' high reflective ceiling inside the plan area of the 10,500 ft2 structure. We have assumed a pair of loudspeakers placed 8 feet above the floor and located 10 feet from the east wall. These two sources were assigned a standard PA loudspeaker directivity, pointed along the length of the structure (— west-southwest), and given a frequency spectrum and sound level from the live band measurements made at The Clifton. Noise Contour Maps A noise contour map is a way of graphically representing the sound level of a particular site. They allow the reviewer to quickly determine the approximate, predicted sound level at any given location in the model, and determine expected compliance with the noise ordinance. In our model, the sound levels on the noise contour maps are calculated on a 20-foot x 20-foot grid at a height of 5 feet, and further interpolated between points on the grid. Sound level ranges are represented with bands of color. For our purposes, most color bands represent a 5 dBA range, with individual noise contour lines (black) within each range representing 2.5 dBA steps. Also on the noise contour maps are buildings shown as brown shapes and the property boundary shown as a black line. httos://weathersoark.com/y/20225(Averane-W eather-in-Charlottesville-Virainia-United-States-Year-Round#Sections-Wind 6 ISO 9613-2 states that the correction factor for wind is typically small and around 0 — 2 dBA. Any correction would cause a reduction in the upwind sound level and an increase in the downwind sound level. >;1tO ACENTECH The Clifton August 11, 2021 Page 7 of 14 SOUND LEVEL PREDICTIONS Using the CadnaA model, we are able to predict sound levels and generate associated noise contour maps for individual sound sources or groups of sources. In an effort to provide clarity to the sound sources at the Collina Farm site we have create three variants, one with only sound due to the gathered crowd of 300 people, the next with the addition of amplified sound at Clifton event reference levels, and finally the same but with amplified sound reduced by 5 dBA. Table 2 shows the variant name, description, and referenced figures that are enclosed with this report. The noise contour maps of these variants are discussed in further detail below. TABLE 2: CONFIGURATION OF CADNAA NOISE MODEL VARIANTS Variant # Description Noise Contours 1 Collina Farm — 300 Person Crowd Figure 2 2 Collina Farm — Crowd & Amplified Sound Figure 3 3 Collina Farm — Crowd & Reduced Level of Amplified Sound Figure 4 The noise ordinance sound level limits are 60 dBA during the day and 55 dBA during the night (starting at 10PM). Color bands in the noise contour map represent sound levels. Any bands colored a shade of white, gray, or green are predicted to be within the daytime and nighttime noise ordinance sound level limits (< 55 dBA). Yellow is the first band that is predicted to be within the daytime but not nighttime sound levels (55 — 60 dBA). Red, purple and blue represent areas of higher sound levels (> 60 dBA) that are predicted to exceed the noise ordinance limits. To determine compliance with the daytime noise ordinance sound level limits, simply verify that all bands of red (> 60 dBA) are inside the property boundary. To determine compliance for nighttime use, simply verify that all bands of yellow (> 55 dBA) are within the property boundary. Figure 1 shows the source locations inside the Collina Farm event structure. Figures 2, 3, and 4 are the noise contour maps, set to the same zoom level for each variant, and include rough approximations of nearby homes, buildings, and major roads for reference. Variant 1— Collina Farm, 300 Person Crowd This variant characterizes the impact of a crowd of 300 people centered in the event structure at Collina Farm, with the west and south walls rolled up. Figure 1 shows the location of this crowd drawn as a red rectangle with hatch marks. Figure 2 shows the noise contour map for this variant, which is predicted to produce sound levels well within the noise ordinance sound level limits. The highest predicted property line sound levels are near 45 dBA across Hurtts Pond at the nearest eastern and southern properties, which are below the ambient sound levels we measured and reported earlier in this review. Variant 2 — Collina Farm, 300 Person Crowd & Amplified Sound This variant characterizes the impact of the amplified sound and the large gathered crowd with the west and south walls rolled up. Based on the proposed event structure, we have assumed that the loudspeaker locations are on the east side of the venue. The music is expected to be loud near the loudspeakers, as is typical of such events. As described in the sound level modeling section above, the sound level of each speaker is based on reference measurements made at actual events at The Clifton, which were measured to be around 85 dBA at a distance of 90 feet. Each loudspeaker was positioned as shown by the red plus symbols in Figure 1. Figure 3 shows the noise contour map for this variant. The amplified sound system and crowd, as modeled, is predicted to produce sound levels within the daytime noise ordinance sound level limits. The highest predicted property line sound levels are around 56 dBA outside the western boundary of the Stone -Robinson Elementary School. Beyond the property line to the south, as the elevation increases after traversing Hurtts Pond, the sound levels are predicted to increase to nearly 58 dBA. The predicted sound levels do not meet the nighttime sound level limit at these locations and exceed the measured ambient sound levels by around 10 dBA. 4))11t0 ACENTECH The Clifton August 11, 2021 Page 8 of 14 Variant 3 — Collina Farm, 300 Person Crowd & Reduced Level of Amplified Sound This variant is identical to variant 2, except the sound level of amplified sound level has been reduced by 5 dBA to a level of 80 dBA at 90 feet (85 dBA at 50 feet, near the expected edge of a dance area). Figure 4 shows the noise contour map for this variant. The 5 dBA reduction in amplified sound level resulted in a 5 dBA reduction across the entire contour map. Beyond the western boundary with Stone -Robinson Elementary School now peaks with around 51 dBA, while the area below the southern boundary across Hurtts Pond is now around 53 dBA. The predicted sound levels meet both the daytime and nighttime noise limits at all locations at or beyond the property boundary. Additionally, these loudest locations are predicted to be only 5 dBA above the measured ambient sound levels. ADDITIONAL CONSIDERATIONS Loudspeaker Orientation Changes to the loudspeaker orientations and positions may change the noise contour maps for the site. Subtle changes should not have a large impact on the contours, but you should make efforts to ensure that loudspeakers are oriented and positioned roughly as shown. If significant changes to location or orientation are made then we recommend the model be re -run with the updated details to review the noise contour maps to verify the project maintains compliance with the noise ordinance. DJ versus Live Band As discussed in the Background section, the DJ and live bands had similar A -weighted sound levels. However, the DJ generated significantly more bass, which is often found to cause higher amounts of annoyance since the rhythmic beat of music is generally dominated by bass, and that will be the most identifiable part of distant amplified music. Care could be taken to limit the amount of bass generated by a DJ. Live music has an added variable of possible stage monitors and guitar amplifiers being introduced outside the house sound system. Additionally, instruments such as drum kits have the potential of being quite loud even when unamplified. The variability of stage monitor loudness might be most easily addressed by requiring performers to use in -ear monitors. Bands should be informed of sound level restrictions and will be expected to comply with any administrative requests. Community Acceptance As you might expect, a noise ordinance is not fully capable of characterizing a neighbor's acceptance of noise. If community members have an adverse reaction to event sound, additional considerations can be made to better address human acceptance of noise due to distant amplified music. These considerations can take the form of a lower overall sound level from the source(s), defining specific sound levels that cannot be exceeded in a given frequency band (such as limiting bass output), or closing the roll -up doors to take the party inside. DISCUSSION & RECOMMENDATIONS In summary, the sound level predictions including the exempt crowd noise and amplified sound meet the daytime noise ordinance limits when using the typical source sound levels measured at current Clifton events. To meet the nighttime sound level limits, we estimate that the amplified music at the Collina Farm events would need to be lowered by 5 dBA (to around 85 dBA at 50 feet, from 90 dBA at 50 feet). You may also consider ending amplified sound at 10PM (the start of nighttime) rather than the 11PM characteristic end time of Clifton events. This would allow the events to only require compliance with the daytime noise ordinance limits and more easily maintain margins between sound levels at1beyond the property line and the maximum allowable sound levels. We recommend aiming to comply with the nighttime sound level limits as outlined above, and limiting amplified sound to 85 dBA at 50 feet from the loudspeaker. 411.0ACENTECH The Clifton August 11, 2021 Page 9 of 14 Areas shown in the noise contour maps in medium green (45-50 dBA) are expected to have sound levels similar to the ambient sound levels we measured and reported above. Light green areas (50-55 dBA) are expected to have sound levels about 5 dBA above the ambient, and yellow areas (55-60 dBA) about 10 dB above ambient. Based on the noise contour map, the majority of the area along and outside the project's property boundary is expected to have event sound levels near or below ambient, though this does not imply inaudibility. We recommend that the Collina Farm event space include a "house sound system,' including all electronics and loudspeakers necessary for these events, and specifically including a closed -loop sound level limiter. We recommend the CESVA LF010 sound level limiter, which measures the sound level in real-time and lowers the volume as necessary when a preset sound level limit is exceeded. This unit will not only help to maintain compliance with the sound level limits, but also provide a record of sound levels during an event and also help to control bass generated by various types of performances (as was apparent between the measured events that included a DJ and live bands at The Clifton). We also recommend that the stage monitors be of the in -ear variety to minimize additional amplified sound that is outside the control of the CESVA limiter. We understand that following our initial discussion of these recommendations, you are pro -actively working with an AV integrator to design such a "house sound system," which will include the CESVA limiter. As a condition of your special use permit approval you may be asked to provide some form of noise monitoring to verify sound levels stay within the noise ordinance. The CESVA sound level limiter should be acceptable for use as a proxy sound monitoring location when used in conjunction with the predicted noise contour maps presented in this report — If limiting to 85 dBA at 50 feet from the loudspeakers, all noise ordinance limits are expected to be met. Specific details of sound monitoring placement and acceptable levels will need to be determined from our model and made in conjunction with the AV integrator and applicable architectural details of the venue. Finally, the model assumes all surface finishes in the event structure (walls, floor, and ceiling) are entirely reflective. While this could be true, we don't expect that you'll be happy with the acoustics of the space and we recommend adding acoustical treatment to the ceiling and north wall. Such treatment will be particularly important when the weather won't allow the walls to be rolled up and the room becomes very reverberant due to the hard surfaces of these walls — reverberant rooms have poor speech intelligibility. We are available to assist you or your architect with the design of room acoustic treatments as a separate service. I hope this letter provides you with the information that you need at this time. If you have any questions, please feel free to contact me at bvoder(dacentech.com or 434.218.0759. Sincerely, Acentech Incorporated Bill Yoder Principal Scientist cc: Kelsey Schlein (Shimp Engineering) Valerie Long (Williams Mullen) •'3,1tO ACENTECH The Clifton August 11, 2021 Page 10 of 14 GLOSSARY OF ACOUSTICAL TERMS We understand that acoustic terminology can be confusing. The following is a brief glossary of some acoustical terms used in this report that you may find useful. Ambient Sound The sound due to environmental, traffic, or other nearby sources that are unrelated to the source(s) being measured or characterized. dB = decibels, dBA = decibels, A -weighted Decibels (abbreviated dB) are used to measure the relative loudness of sound, based on a logarithmic scale. For reference, normal human speech is in the range of 65 decibels, painful rock music may be more than 110 decibels, while aircraft noise may be as loud as 130 decibels. A -weighting filters the sound in a way that is similar to human hearing, and was found to be correlated to annoyance from environmental sound. Hence, dBA levels are often referenced in various acoustical standards. Note that a 10 dB increase in sound is associated with a perceived doubling in sound level. Directivity The pattern in which sound radiates from a given source. This could be spherical, hemi-spherical, or some other pattern. Directivity changes with frequency and is related to the size and shape of the source. Frequency, Hz The number of cycles or oscillations per second. Low frequency is associated with bass and are low pitch, while higher frequencies are high pitched. Leq The equivalent continuous sound level, or energy -average sound level, over a defined measurement period. Note that the sound level may be higher or lower during a given measurement period. Octave Band An octave band is a frequency band where the highest frequency is twice the lowest frequency, and characterized by its center frequency. Bands are proportional in width, being wider at higher frequency. Pink Noise Noise in which each octave band has equal energy. Propagation Loss A reduction of sound energy due to distance, absorption, and other means. Sound Power Level This is the level used to define the amount of acoustic power generated by a particular sound source. Sound Pressure Level This is the level used to characterize the loudness of a sound at a specific location. In this review, sound pressure is implied unless the language specifically indicates sound power. Temperature inversion A reversal of the normal behavior of temperature near the ground. This occurs when a layer of warmer air covers a layer of cool air at the surface. This can allow sound to reflect off the warmer air and travel to a greater distance. 4))11t0ACENTECH The Clifton August 11, 2021 Page 11 of 14 Figure 1: Collina Farm Expected Outdoor Venue, 300 Person Crowd and Loudspeaker Pair Locations 0 1 t-- & 0