Subject: Pappy s Grill and Sports Bar DJ System Acoustical Isolation Study

Transcription

1 Page 1 of 8 WI # December 21, 2016 Alex Popov Liquid Entertainment 2367 Telegraph Avenue Berkeley, California Subject: Pappy s Grill and Sports Bar DJ System Acoustical Isolation Study Dear Alex, This letter presents the results of the noise analysis conducted to determine the relative noise levels transmitted to residential dwelling associated with the operation of the DJ sound system in the basement bar of Pappy s Grill and Sports Bar located at 2367 Telegraph Avenue in Berkeley, California. It presents data collected from short term measurements pertaining to the noise transmission associated with the operation of the DJ sound system to the residential dwellings units on the upper stories from 9pm on Thursday December 1 st to 1:30am on Friday, December 2 nd, The measured sound levels associated with the operation of the sound system are presented and compared to the criteria pertaining to noise levels in the Berkeley Municipal Code. The noise study concludes that the sound transmission levels of the overall building sound system were not in compliance, however, the DJ sound system itself complies with the City of Berkeley s City Noise Ordinance based on definitions and regulations as stipulated in said Ordinance. The exceedance of the overall building sound system was due to the placement of a subwoofer in the bar/restaurant above the basement bar and below the residential dwellings of the second story. It is our understanding that the subwoofer has currently been disconnected until modifications can be performed. Herein are the findings of the study. Applicable Definitions The City of Berkeley provides definitions for the City Noise Ordinance in Section Definitions of Ordinance No. 7,122 N.S. The applicable definitions pertinent to the study are as follow: B. "A weighted sound level" means the sound level in decibels as measured on a sound level meter using the A weighting network. The level so read is designated db(a) or dba. C. Ambient noise level means the composite of noises from all sources near and far. In this context, the ambient noise level constitutes the normal or existing level of environmental noise at a given location, minus the source which is the subject of enforcement. D. "Amplified sound" means any sound created by the use of sound amplifying equipment.

2 PAPPY S GRILL AND SPORTS Page BAR 2 of 8 G. "Cumulative period" means an additive period of time composed of individual time segments which may be continuous or interrupted. EE. "Sound level meter" means a sound measuring instrument meeting American National Standard Institute's Standard S or most recent revision thereof for Type 1 or Type 2 sound level meters or an instrument and the associated recording and analyzing equipment which provide equivalent data. (Ord NS 2, 2009: Ord NS 1 (part), 1982) Per Section , sound level meters should be set utilizing the "A" weighting scale and the "slow" meter response. (Ord NS 4, 2009: Ord NS 1 (part), 1982) Applicable Regulations The City of Berkeley Noise Ordinance stipulates the following pertinent regulations for amplified music and speech systems in relation to residential multi family dwellings. Section Interior noise standards paragraph A Maximum permissible dwelling interior sound levels states that The interior noise standards for multi family residential dwellings as presented in Table shall apply, unless otherwise specifically indicated in other codes, within all such dwellings with windows in their normal seasonal configuration. The following table is taken from the noise ordinance and provides interior noise limits for various times of the day. Section , Permissible levels for entertainment establishments, states that an entertainment establishment may exceed the sound level limits by no more than five decibels higher than either the applicable standard or the ambient noise level, whichever is higher. Thus, per Section , this specifically indicated allowance for entertainment establishments shall apply to the allowable interior noise level limits as presented in Table resulting in permissible noise levels as follows: 10:00 p.m. 7:00 a.m. 45 dba 7:00 a.m. 10:00 p.m. 50 dba Section , Prohibited acts, item B.12 Places of Public Entertainment states that it is prohibited to operating or permitting the operation or playing of any loudspeaker, musical instrument, motorized racing vehicle, or other source of sound in any place of public entertainment that exceeds 95dBA as read on the scale of a sound level meter at any point normally occupied by a customer, without a conspicuous and legible sign stating: "WARNING! SOUND LEVELS WITHIN MAY CAUSE HEARING IMPAIRMENT." 2

3 PAPPY S GRILL AND SPORTS Page BAR 3 of 8 Interior Noise Survey Methodology For the purposes of this report the basement level where the DJ sound system is located shall be referred to as the lower level. This is the lowest level of the building below street level. The bar/restaurant located above, at street level, shall be referred to as the main level. The residential stories begin on the second story of the building, above the main level. Measurements were taken on the second story which shall be referred to as the residential level and can be considered the worst case scenario for noise transmission to the residential dwellings. Calibrated, digital recordings were made at locations within the building to measure the existing sound levels from the DJ sound system in the lower level and determine the level of transmitted noise to the residential level. The measurements were taken at a height of 5 feet above the ground and a minimum 3 feet away from any walls or other acoustically reflecting surfaces. The Type 1 sound level meter and associated recording equipment utilized comply with definition EE sound level meter in Section of the noise ordinance and were set to slow response. Sound level meters set to slow response energy average the fluctuating sound level of music over a short period of time minimizing the impact of higher sound level transients. The resulting slow response sound level is a commonly used measurement technique to measure the effect of typical noise levels (e.g., music) on humans and is the setting specified in Section This interior noise survey consisted of measurements both in the lower level with the DJ sound system playing music and at the end of the residential level in a hallway located at the front of the building outside of units 207 and 208. The hallway measurement location was used rather than a location within a unit, because the location was observed to have the highest levels of noise transmission from the music below to the residential level. Measurement Results Table I in the Measurement Results section below summarizes the lower level noise measurement locations, the noise level measured at each location and the arithmetic average sound level (90dBA) of the six measurements. The frequency spectra of the measurements are also illustrated in Figure 1. For reference, the noise level from the music played in the lower level was also measured in the center of the seating area on the main level (bar/restaurant). The bar/restaurant was near full capacity during the testing. The DJ system in the lower level was on, but it was not audible over the patron noise level (86dBA). Patron noise from any part of Pappy s operation was not perceived in the residential level above and as such was not an influence on the measurements. After documenting the sound levels in the lower level with the DJ system in operation, measurements were taken in the hallway on the residential level (second story) of the building to determine the amount of noise transmission to the residential dwellings. Existing noise levels were determined by analyzing short term data obtained at the site as previously described with the metric of the Equivalent Level or Leq which is the level of a steady noise which would have the same energy as the fluctuating noise level at the measurement location. It is the average level of the energy of all the sounds occurring over a specified time period. 3

4 PAPPY S GRILL AND SPORTS Page BAR 4 of 8 Measurements were performed at six locations in the lower level to establish the sound level at the location of noise generation. The measurement locations and results are presented in Table 1. TABLE 1- Lower Level Noise Survey Measurement Locations and Results Location Location Description Measured Noise Level B 1 Directly in Front of the Speaker (8 ~ 10 ) 92 dba B 2 Back Left by Pool Table 89 dba B 3 Back Right by Men s Restroom 85 dba B 4 Front Left to the Side of the Speakers 90 dba B 5 Front Right by the Back of the Stairs 90 dba B 6 Center of the Floor by the Stage 92 dba Average: 90 dba Measurements were also taken in the hallway of the residential level as previously described. The original intent was to document one extended measurement, however, during the preliminary testing on the residential level, before the extended test could begin but after several shorter tests had been documented, a substantial increase in sound levels suddenly occurred. Testing was ceased and an informal survey of the building was undertaken to determine the cause of the increase in the sound levels. The source of the sound increase was a component of the primary building sound system located on the main level, which had been activated to play the DJ music in the main bar/restaurant area, and not the DJ sound system in the lower level. The component identified as the source of the increased sound levels and building vibration was a JBL Model ASB6112 subwoofer placed on a concrete beam by the front window. The subwoofer was generating a substantial level of low frequency sound and inducing vibration in the structure which radiated throughout the building. The noise levels on the residential level prior to the activation of the JBL subwoofer were in the range of 40 to 42dBA which allows a slight safety buffer before reaching the maximum level of 45dBA stipulated for entertainment establishments. The JBL subwoofer has an operating range (f 3dB ) down to 43Hz before the output begins to decline sharply which was observed in the test data. Given that the source of possible exceedances had been identified two tests were performed: the first with and the second without the main level JBL subwoofer in operation. The two measurements were intended as a comparison to illustrate the difference between the levels and isolate the primary factor causing the noise levels to approach or exceed the levels stipulated by code. The analysis of the noise data collected during our testing indicates that an unexpected circumstance occurred during the testing: the sound output of the system decreased by 5dB during the testing period intended to document the DJ music sound levels. This occurred at the end of the first testing period with the main level JBL subwoofer on. The decrease occurred in the DJ sound system which in turn decreased the sound output of the building sound system resulted in an invalid final portion of the first test with the main level subwoofer on and an invalid second test with only the DJ sound system operating and the main level JBL subwoofer off. To properly compare the two test conditions only the portion of the first test period (JBL subwoofer on) recorded prior to the decrease in sound system output was 4

5 PAPPY S GRILL AND SPORTS Page BAR 5 of 8 utilized. The noise level just prior to the decrease was 46dBA with the main level JBL subwoofer on. For the measurement without the main floor subwoofer in operation (i.e. off), a one minute data sample taken earlier in the evening prior to the decrease in DJ sound system output has been utilized. The sample was measured at 41dBA which is in compliance with the City of Berkeley Noise Ordinance as it relates to entertainment establishments as well as within the 40 to 42dBA range typically observed earlier in the evening. As previously mentioned this level provides a slight safety buffer before noise levels reach the 45dBA limit specified by the Noise Ordinance. The frequency spectrum results of the two measurements can be found in Figure 2. As illustrated in Figure 2, a substantial increase in low frequency noise occurred when the main level JBL subwoofer was in use. The increase in high frequency noise depicted in Figure 2 is believed to be caused by the rattling of the light fixtures in the hallway ceiling induced by the vibration of the structure which the subwoofer created. Recommendations To mitigate the sound level associated with the JBL ASB6112 subwoofer on the main level it is recommended that the subwoofer remain disconnected or shall be: 1. Located a minimum distance of 15 feet from the front window. 2. Mounted with appropriate vibration isolation a. Suspended from the ceiling: Combination spring and neoprene isolation with a minimum 2 inch deflection. i. Acceptable products include Kinetics Noise Control Model ICC or Muta isolation hangers or Mason Industries 30N Series isolation hangers ii. The isolation hangers should be located directly attached to or as near the ceiling as possible. A location in the ceiling area should be sought out which is rigid such as a primary joist to mount the isolators to. iii. A minimum distance of 24 should be maintained between the ceiling and the subwoofer. b. Resting on the floor: Resilient pad isolation similar to Mason Super W industries.com/masonind/products/neoprene mounts/ or Kinetics Noise Model RSP 5

6 PAPPY S GRILL AND SPORTS Page BAR 6 of 8 Conclusion This analysis based on short term measurements with the DJ sound system operating indicates that the Pappy s sound system, without the main level JBL ASB6112 subwoofer, complies with the City of Berkeley s Noise Ordinance based on definitions and regulations as stipulated in said Ordinance. It is anticipated that relocating and isolating the JBL subwoofer as discussed above will allow the use of the subwoofer and compliance with the Noise Ordinance. Very truly yours, WILSON IHRIG Robert B. Astrom Associate Pappys DJ System Noise Transmission to Apartments Study.docx 6

7 PAPPY S GRILL AND SPORTS Page BAR 7 of 8 1/3 Octave Band Sound Pressure Level, db re 20 Pa Figure 1: Measurements at six location in the basement with DJ system operating 7

8 PAPPY S GRILL AND SPORTS Page BAR 8 of 8 1/3 Octave Band Sound Pressure Level, db re 20 Pa Figure 2: Measurements in residential story hallway with and without main level subwoofer 8