acoustic panel MaxBell Acoustic Panels at the Elvis Room - Bakehouse Studios, Richmond, Victoria MaxBell Acoustic CASE STUDY FOR THE INSTALLATION OF

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1 Unpainted Panels Painted Panels acoustic panel CASE STUDY FOR THE INSTALLATION OF MaxBell Acoustic Panels at the Elvis Room -, Richmond, Victoria Address: 20 Suffolk Road, Surrey Hills, VIC 3127 Phone: Fax:

2 About the MaxBell Acoustic Panel Case Study Results Elvis Room Dimensions 11.1m Elvis Room 4.7m 6.0m 8.0m MaxBell Acoustic Panels Reverberation Time (Seconds) Bare Room Bakehouse Before and After Installation Of Painted panels Frequency (Hz) Painted Panels The results are taken from the Renzo Tonin Acoustic Report included in this study. The graph shows clearly the benefit of the acoustic panels and particularly the low frequency performance of the panels. The panels were also painted in colours chosen by the clients and were discernibly different in terms of architectural aesthetics from other reverberation control measures. Introduction Background MaxBell Acoustic Panels were installed in the Elvis Room at the Bakehouse Rehearsal Studios in Richmond Victoria. This application was the basis of a Case Study which examined the acoustic absorption performance of the Maxbell Acoustic panels and the test room before and after installation. MaxBell Acoustic Panels are a new form of reverberation control designed to absorb noise, yet retain the aesthetic of flat plasterboard walls and ceilings once painted. The panels are installed in the same manner as plasterboard and can be jointed using standard wet plaster techniques such that joins are rendered invisible once painted. The Elvis Room is a large venue used on a continuous basis as a rehearsal room by a range of musicians. The acoustic performance of the room is very important to the users in terms of in room reverberation, as well as exterior (room to room) sound levels. The room typically has curtains installed with a plasterboard faced ceiling. Two sides of the room have plasterboard walls, whilst the remainder is painted brickwork. Renzo Tonin and Associates were contracted to independently test reverberation times in the Elvis room before and after installation of the MaxBell Acoustic Panels and their report is copied at the back of this case study. MaxBell Acoustic panel has a bevilled edge around the complete perimeter of the panel such that the panel can be joined side by side and end on end using standard plasterboard joining methods. The joints can be stopped in the same manner as plasterboard providing an invisible joint once the panel has been painted.

3 Installation of Walls Installation of Ceilings The installation of Maxbell Acoustic panels on ceilings is similar in concept to installation on walls. Panels should be installed with fasteners at 400 to 600 centres and using smoothed stud adhesive. Fasteners through the middle of the panel should be at 600 centres. The panels are flexible and difficult to hold up during installation. It is strongly recommend that panels are installed with a panel lifter (left). If not, two people are required to hold up the panel, whilst a third applies the fasteners. Again if it is necessary to cut panels to fit a room, then any cut edge should be to the outside of an installation and covered by a strip or cornice. Any wet plaster joints should only use the bevilled edge of a panel and great care taken to not allow any plaster to cover a membrane diaphragm. MaxBell Acoustic Panels are designed to be installed in a similar manner to plasterboard ceilings and walls. Ideally furring channel or timber supports are used. The panels can be applied directly to a wall, but better low frequency response is achieved by the inclusion of an airgap behind the panel. Further, middle and low frequency response is improved by the inclusion of insulation in the airgap. The panels are very light and somewhat flexible, so great care needs to be taken during installation. The lightweight requires support at 600 centres and around the complete outer edge of each panel. Because the panels are flexible the surface will follow the support system and not bridge any sections. Great care is needed during the framing to ensure that the supports are as level as possible for an optimum result once the panels are installed. MaxBell Acoustic Panels are installed by fastening the panels to the supports using standard plasterboard screws at between 400 and 600 centres. It is recommended that stud adhesive is smoothed over the supports to ensure the panel follows the support completely. It is strongly recommended that dobs of adhesive are avoided, as these could impact the membrane diaphragms. Because of the flexibility of the panels, wherever a joint is to be applied, the panel must be supported underneath. Supports could be installed as suggested in the photo (above). Where a panel needs to be cut across diaphragms, it is strongly recommended that the cut edge is not used to join to an adjacent bevilled edge. Planning of panel layout should ensure that a cut edge is not plaster joined and should be used at the edge of the installation and hidden by some form of edging or preferably cornice.

4 Plastering of Joints Painting of MaxBell Acoustic Panels MaxBell Acoustic Panels are supplied with a bevilled edge similar to standard plasterboard. The bevilled edge is applied completely around the panels so that sheets can be joined edge to edge or end to end. Joins are made in the same manner as normal wall board with reinforcing tape and a three pass technique, followed by appropriate sanding. Great care must be taken to ensure no plaster is applied to any of the membranes as the diaphragm will distort and not flatten out when painted. The MaxBell Acoustic panels installed at the Bakehouse utilised a paper membrane that when painted, flattened out and produced a similar result to painted plasterboard. The paper is treated with a coating that requires only two coats of a standard, water based acrylic interior paint applied with a roller. Flat or semi sheen is recommended. Acoustically, extra paint will reduce high frequency absorption.

5 MaxBell Acoustic Reverberation Testing at the Elvis Room -, Richmond, Victoria 29 January 2010

6 Consultants in Acoustics, Vibration & Structural Dynamics website: MA MAXBELL ACOUSTIC REVERBERATION TESTING BAKEHOUSE STUDIOS MA357-01F02 (REV 2) ACOUSTIC REPORT BAKEHOUSE 29 JANUARY 2010 Prepared for: 20 Suffolk Road Surrey Hills, VIC 3127 Attention: Mark Borroni Member of the Association of Australian Acoustical Consultants Melbourne Renzo Tonin & Associates (VIC) Pty Ltd ABN Suite 107, 757 Bourke Street, DOCKLANDS, VIC 3008 Ph (03) Fax (03) Sydney (Head Office) Brisbane Gold Coast Kuwait

7 DOCUMENT CONTROL Date Revision History Non- Issued Revision Issued Revision Prepared By (initials) Instructed By (initials) Reviewed & Authorised by (initials) Initial Revision 0 PT Peer review 1 RB Amended 2.1 Description 2 PT The work presented in this document was carried out in accordance with the Renzo Tonin & Associates Quality Assurance System, which is based on Australian Standard / NZS ISO This document is issued subject to review and authorisation by the Team Leader noted by the initials printed in the last column above. If no initials appear, this document shall be considered as preliminary or draft only and no reliance shall be placed upon it other than for information to be verified later. This document is prepared for our Client's particular requirements which are based on a specific brief with limitations as agreed to with the Client. It is not intended for and should not be relied upon by a third party and no responsibility is undertaken to any third party without prior consent provided by Renzo Tonin & Associates. The information herein should not be reproduced, presented or reviewed except in full. Prior to passing on to a third party, the Client is to fully inform the third party of the specific brief and limitations associated with the commission. The information contained herein is for the purpose of acoustics only. No claims are made and no liability is accepted in respect of design and construction issues falling outside of the specialist field of acoustics engineering including and not limited to structural integrity, fire rating, architectural buildability and fit-for-purpose, waterproofing and the like. Supplementary professional advice should be sought in respect of these issues. Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 2

8 CONTENTS 1 INTRODUCTION 4 2 METHODOLOGY MaxBell Panels Equipment Test Method Room Description Room Test Configurations 6 3 RESULTS Reverberation Time Results 7 4 CONCLUSION 9 APPENDIX A - GLOSSARY OF ACOUSTIC TERMS 10 APPENDIX B - REVERBERATION TIME RESULTS CHART 13 List of Tables Table 1 Octave Band Results Summary 7 Table 2 Third-Octave Band Reverberation Time Results 7 Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 3

9 1 INTRODUCTION Renzo Tonin & Associates was engaged by to carry out reverberation testing at, Hoddle Street, Richmond for the purpose of measuring the effectiveness of Panels in the control of reverberation times. The Elvis rehearsal room was selected as the test location. Reverberation time testing was conducted on two occasions for each of two configurations. On the first occasion the room was tested in its original state, with folded velour curtains covering the majority of the walls, and then with the curtains removed. On the second occasion, subsequent to the installation of the MaxBell panels the room was once again tested with the curtains in place, and then again with the curtains removed. This report outlines the results of the reverberation testing and the effects that the MaxBell panels had on the reverberation time of the tested rehearsal room. The work documented in this report was carried out in accordance with the Renzo Tonin & Associates Quality Assurance System, which is based on Australian Standard / NZS ISO Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 4

10 2 METHODOLOGY 2.1 MaxBell Panels MaxBell proprietary acoustic panels are a perforated polyester panel with a paintable paper facing. The panels are manufactured from a mixture of virgin and recycled materials. The panels installed in the test room were 10mm thick with perforations (behind the paper facing) of several diameters. Two coats of acrylic paint had been applied to the panels subsequent to installation. 2.2 Equipment Reverberation measurements were conducted with a CEL 593 Precision Sound Level Meter which is classified as a Type 1 instrument as defined in AS Sound Level Meters and is suitable for field and laboratory use. The sound level meter has been calibrated to Australian Standards by a certified NATA laboratory. Other equipment employed during testing included a white noise signal generator (with a frequency range of at least 100Hz-5kHz), amplifier and speaker, providing sound levels up to 100dB. The sound level meter was calibrated prior and subsequent to the measurements using a Bruel & Kjaer Type 4231 Acoustic calibrator. No significant drift in calibration was recorded. 2.3 Test Method The testing was conducted using a continuous method whereby the room is filled with a diffuse sound field of broadband noise and upon the abrupt cessation of the noise, the decay was measured by the sound level meter. To ensure the sound field approximates a diffuse condition the speaker is positioned in a corner of the room angled upwards and facing reflective surfaces (where practicable). The decay (reverberation time, time taken for a level reduction of 60dB) was measured in five positions within the room for each of two speaker (noise source) locations. Measurement positions were selected so as to be at least 1m away from the test room walls and at least 2m from the noise source. Collected reverberation time data was stored on the sound level meter s internal memory and later downloaded for data analysis. In most cases (where possible) the T30 metric was utilised as the basis for the assessment of reverberation time. In some cases, at the 100Hz and 125Hz third-octave bands, the T30 could not be measured due to excessive low-frequency background noise. In these cases the T20 was utilised instead. 2.4 Room Description The test room has a volume of approximately 200m 3 and a floor area of approximately 63m 2. The non-symmetrical room comprises 6 internal walls. Two doors in the room provide access Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 5

11 from the corridor and to a small store room. The room also features a drum riser approximately 150mm in height. In its original state, the room s wall surfaces were a combination of masonry, plasterboard and strawboard. Floor to ceiling folded velour curtains covered all wall surfaces. It is understood that the ceiling consisted of several layers of plasterboard with an air-gap to timber joists of the room above. The room floor was covered with several layers of carpet and rugs scattered throughout. For all tests, the room was fully furnished with several large couches, a coffee table and some other small furnishings along the perimeter of the room. Several large J-Bin PA and other regular foldback speakers were also present in the room. For the second set of tests, the MaxBell panels were installed over all but two of the larger walls (approximately 45% wall area) and over the majority of the ceiling (approximately 95% ceiling area). The walls that were treated with the panels also included a plasterboard kick panel up to a height of approximately 500mm to reduce the possibility of panel damage. 2.5 Room Test Configurations Tests 1 & 2 were conducted with the room in its original configuration (as described in section 2.4) with and without curtains, respectively. Tests 3 & 4 were conducted subsequent to the installation of the MaxBell panels, with and without curtains, respectively. On the walls, the panels were installed with a 20mm cavity with 15mm polyester insulation behind. On the ceiling, the panels were installed with a 100mm cavity with 75mm polyester behind. Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 6

12 3 RESULTS 3.1 Reverberation Time Results A summary of reverberation time results is presented in Table 1 and Table 2, below. A chart of the third-octave band results is presented in APPENDIX B. Table 1 Octave Band Results Summary Test Room Configuration Octave Band Reverberation Time (secs) k 2k 4k 5k Mid-Frequency Reverberation Time (secs) Test 1 Initial w/ curtains Test 2 Initial w/o curtains Test 3 MaxBell w/ curtains Test 4 MaxBell w/o curtains Table 2 Third-Octave Band Reverberation Time Results Test Third-Octave Band Reverberation Time (secs) k 1.25k 1.6k 2k 2.5k 3.15k 4k 5k Test Test Test Test The results of Test 1 show that the room was originally quite dead with the third-octave bands from 100Hz 500Hz displaying reverberation times between 0.3 and 0.6 seconds and frequencies from 630Hz and above generally ranging between 0.2 and 0.3 seconds. The highest reverberation time measured was 0.57 seconds at 200Hz. With the curtains removed, the results of Test 2 show that the room exhibited a much more even reverberation time across all frequencies, with the reverberation time at the majority of third-octave bands ranging between 0.6 and 0.8 seconds and the highest reverberation time of 0.75 seconds at 500Hz. Following the installation of the MaxBell Panels the reverberation time of the room decreased at all measured frequencies for both configurations. For the tests conducted with curtains, the installation of the MaxBell panels resulted in a significant reduction of reverberation times below 500Hz. In comparison, the tests conducted without curtains showed a significant reduction in reverberation time over a greater range, from 160Hz to 1.25kHz. Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 7

13 The maximum reverberation time measured for Test 3 was 0.43 seconds at 100Hz and 0.62 seconds at 4kHz for Test 4. The most pronounced reductions in reverberation time were observed at 250Hz and 1kHz, which are expected to correspond with the MaxBell panels natural frequencies for the two installed configurations (cavity depths). Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 8

14 4 CONCLUSION Renzo Tonin & Associates has completed an assessment of the effectiveness of MaxBell proprietary acoustic panels in reducing reverberation time within a test room. The conducted tests and analysis found the panels to reduce reverberation time across the entire tested frequency range. The most significant reduction was measured in the frequency range from 100Hz to 1.25kHz. It is expected that this product could be installed in applications where it is required to reduce reverberation times in the lower and middle frequencies. The testing has shown that the product works to great effect in the lower and middle frequencies, even when covered by (and used in conjunction with) a high frequency absorber such as heavy folded curtains. Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 9

15 APPENDIX A - GLOSSARY OF ACOUSTIC TERMS The following is a brief description of the technical terms used to describe noise to assist in understanding the technical issues presented. Adverse Weather Weather effects that enhance noise (that is, wind and temperature inversions) that occur at a site for a significant period of time (that is, wind occurring more than 30% of the time in any assessment period in any season and/or temperature inversions occurring more than 30% of the nights in winter). Ambient Noise The all-encompassing noise associated within a given environment at a given time, usually composed of sound from all sources near and far. Assessment Period The period in a day over which assessments are made. Assessment Point A point at which noise measurements are taken or estimated. A point at which noise measurements are taken or estimated. Background Noise Background noise is the term used to describe the underlying level of noise present in the ambient noise, measured in the absence of the noise under investigation, when extraneous noise is removed. It is described as the average of the minimum noise levels measured on a sound level meter and is measured statistically as the A-weighted noise level exceeded for ninety percent of a sample period. This is represented as the L 90 noise level (see below). Decibel [db] The units that sound is measured in. The following are examples of the decibel readings of every day sounds: 0dB The faintest sound we can hear 30dB A quiet library or in a quiet location in the country 45dB Typical office space. Ambience in the city at night 60dB Martin Place at lunch time 70dB The sound of a car passing on the street 80dB Loud music played at home 90dB The sound of a truck passing on the street Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 10

16 100dB The sound of a rock band 115dB Limit of sound permitted in industry 120dB Deafening db(a): A-weighted decibels The ear is not as effective in hearing low frequency sounds as it is hearing high frequency sounds. That is, low frequency sounds of the same db level are not heard as loud as high frequency sounds. The sound level meter replicates the human response of the ear by using an electronic filter which is called the A filter. A sound level measured with this filter switched on is denoted as db(a). Practically all noise is measured using the A filter. Frequency Frequency is synonymous to pitch. Sounds have a pitch which is peculiar to the nature of the sound generator. For example, the sound of a tiny bell has a high pitch and the sound of a bass drum has a low pitch. Frequency or pitch can be measured on a scale in units of Hertz or Hz. Impulsive noise Having a high peak of short duration or a sequence of such peaks. A sequence of impulses in rapid succession is termed repetitive impulsive noise. Intermittent noise The level suddenly drops to that of the background noise several times during the period of observation. The time during which the noise remains at levels different from that of the ambient is one second or more. L max The maximum sound pressure level measured over a given period. L min The minimum sound pressure level measured over a given period. L 1 The sound pressure level that is exceeded for 1% of the time for which the given sound is measured. L 10 The sound pressure level that is exceeded for 10% of the time for which the given sound is measured. L 90 The level of noise exceeded for 90% of the time. The bottom 10% of the sample is the L 90 noise level expressed in units of db(a). L eq The equivalent noise level is the summation of noise events and Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 11

17 integrated over a selected period of time. Reflection Sound wave changed in direction of propagation due to a solid object obscuring its path. SEL Sound Exposure Level (SEL) is the constant sound level which, if maintained for a period of 1 second would have the same acoustic energy as the measured noise event. SEL noise measurements are useful as they can be converted to obtain Leq sound levels over any period of time and can be used for predicting noise at various locations. Sound A fluctuation of air pressure which is propagated as a wave through air. Sound Absorption The ability of a material to absorb sound energy through its conversion into thermal energy. Sound Level Meter An instrument consisting of a microphone, amplifier and indicating device, having a declared performance and designed to measure sound pressure levels. Sound Pressure Level The level of noise, usually expressed in decibels, as measured by a standard sound level meter with a microphone. Sound Power Level Ten times the logarithm to the base 10 of the ratio of the sound power of the source to the reference sound power. Tonal noise Containing a prominent frequency and characterised by a definite pitch. Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 12

18 APPENDIX B - REVERBERATION TIME RESULTS CHART Renzo Tonin & Associates (VIC) Pty Ltd MA Reverberation Testing 29 January 2010 Page 13

19 Test Room Reverberation Time T1 - Room with Curtains T2 - Bare Room T3 - Maxbell Panel with Curtains T4 - Maxbell Panel Bare Room 0.70 Reverberation Time (secs) Third-Octave Centre Frequency (Hz) Renzo Tonin Associates 107 / 757 Bourke Street, Docklands VIC 3008 (03) MA357-01S06 (rev 0) RT Results MaxBell Bakehouse Panels