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HomeMy WebLinkAboutM-81-047910 r 7 SOUND SYSTEM EVALUATION _F0,F CITY„ COMMISSION-CHNIBERS PREPARED BY: FLOYD JOUBERT DEPT. COMPUTERS & COMMUNICATIONS COMMUNICATIONS SERVICES DIVISION MAY 28, 1981 SW SYSTEM EVALUATION 1.() 1VTRODUCTION PAGE 1 PURPOSE 10 JNVESTI-GATE SOUND SYSTEM PROBLEMS IN CITY COMMISSION CHAMBERS DUE TO COMPLAINTS BY CITY OFFICIALS OF POOR SOUND QUALITY DURING CITY MEETINGS. OBJECTIVES .° DEFINE EXISTI:NG SOUND SYSTEM PROBLEMS o RECOMMEND SOLUTIONS AND ASSOCIATED COSTS EVALUATION .APPROACH CHAMBER ACOUSTICAL CHARACTERISTICS PUBLIC ADDRESS SOUND SYSTEM PAGE 2 SOMID aaTEK EV .Lt! - l 2A EXISTING SOUND SYSTEM 'PROBLEMS t!IA'NY FACTORS CONTRIBUTE 70 SOUND QUALITY WITHIN THE CITY COMMISSION I CHAMBERS CHARACTERISTIC it Tk,)0 PRINCIPAL. FACTORS 'CONTRIBUTING TO SOUND PROBLEMS ARE THE ACOUST 'OF THE CHAMBER AND THE PUBLIC ADDRESS SOUND SYSTEM. 2.1 ACOUSTICAL ,CHARACTERISTICS : CI; IT CONSTRUCTION o H16H .CEILINGS EXPOSED :CONCRETE WALLS PARTIAL 'WALLS . OPEN .AREAS AND NO DOORS o NOISY AIR CONDITIONING SYSTEM CURTiAINS, CEILINGS, AND SOUND :LACTIC DE ACOUSTICAL .ABSORTION MATERIAL (ARNTERFERENCE. BAFIF-LE'S) TO REDUCE BACKGROUND ACOUSTICAL PAGE 3 MID S S EM EM I0 AiC013STICAL {C°tiARACTFRI.STTCS (CON'T) NO_EfV.E S DB OF AMBIENT NT NOISE LEVEL MEASURED AT CENTER OF CHAMBER. o AIR CONDITIONING SYSTEM IS A MAJOR CONTRIBUTOR TO THE AMBIENT ISOIS ED LEVEL, �lOISE LEyfi. INCREASES TO 76 DB AS MEASURING INSTRUMENT TOWARDS THE AIR CONDITIONING EQUIPMENT. THE SOUND AMBIENT NOISE SE 'LEVEL OF CHAMBER INCREASE S FROM �.O TO 14 DBNTHE EXISTING S Y�TE,M IS T:URNfD ON BECAUSE of OPEN r1ICROPHONES WSTSHAMPLIFYBOTH PODIUMS AND NOISE LEVEL OF THE CHAMBER OPEN MICROPHONESNAT COMMISSIONER DESK. THOSE THAT ARE INADVERTENTLY LEFT ON AT CHAMBER, :UM ACCOUNTS FOR AN ADDITIONAL 3 DB OF NOISE WITHIN THE AMPLIFIERtiEEN NORMAL DT'STINGUISHABL E VOICECONVERSATIONS BETWEEN TWO PEOPLE RANGE BEENTER ABOVE THE AMBIENT ENVIRONMENT NOISE LEVEL AS MORE PEOPLE 3 ,AND 5 DB AB CONVERSATIONS WITHIN THE AUDIENCE AN OVERALL INCREASE OF AMBIENT NOISE INTO C RESULTS :WHICH IS .A FUNCTION OF THE SIZE OF THE AUDIENCE. PAGE 4 SOU �D S_YSTEM EVALL' OP! 2.1 AC00STICAt CHARACTERISTICS (CON'T) IIDI N .E ONTUE91ED NOISE NGS AUDIENCE NOISE LEVEL INCREASES DUE TO SMALL GROUP DARING �IEETI � OF BAT INN S HALLWAY MEETINGS, AND AMBIENT NOISE. TOTAL NOISE aCONVEI2THIS 15 To 3`� DB CAN BE EXPECTED. AMPLIFIER GAIN IS SET OVERCOME TO VOISE LEVEE WHICH CAUSES THE SOUND SYSTEM TO BECOME MORE FEEDBACK AND DISTORTION. OPEN t4lCROP:HONES FURTHER DEGRADES THE SOUND SYSTEM. ELLATION TYPE WHICH ARE USUALLY EXISTING t4ICROPHON ES ARE NOT NOISE CANC SPECIFIED FOR USE 'IN THIS ENVIRONMENT. millill PAGE 5 2.2 10 t ogin SSE M-1 EMM-TI-21 PUBLIC ADDRESS SOUND SYSTEM TEE EXISTING K)BLIC SOUND SYSTEM DOES FUNCTION, BUT HAS THE FOLLOWING PROBLEMS: to OBSOLETE AMPLIFIERS (HUM AND DISTORTION) o WRONG TYPE MICROPHONES . NOISY SPEAKERS V I-!MPROPER PLACEMENT OF SPEAKERS CAUSING DEAD SOUND SPOTS WITHIN CHAMBERS PAGE 6 SO_ SaEEM EV A LU IO 3.10 lRECOMMEINDATIiONSICOST:S .TiHE POLLOW I SIG RECOMMENDATIONS OFFER ALTERNATIVES TO INCREASE THE SOUND QUALITY MITMI,N THE COMMISSION CHAMBERS or 4j_JlIj T 'S2t Q T�jS R£�DMM£i�DATION REQUIRES A MAJOR FACILITY MODIFICATION WHICH INCLUDES: RBTION PANELS I�IST�►LLAT20N Of FALSE CEILING WITH ACOUSTICAL P.BSO z jjEM cARPETIING , DSE DF SOUND ABSORBTION MATERIAL ON HARD WALLS ELIMINATION OF ALL OPEN AREAS I?NST,AI-tATION OF SOUND PROOF DOORS oLOW EFFICIENCY 'SPEAKERS IN CEILING I 1STA.LATION OF ,, NEW SOUND SYSTEM b REPLACEMENT OF :MICROPHONES D NEW DISTRIBUTED AIRCONDITIONING SYSTEM EST I MATED COST - $7 5, 000 PAGE % SOUND MI -Eft EVALUELOA 3,0 RECOMMENDATIONSICOST }(C-OSTJT) THIS IS A PARTIAL SOLUTION A LESS COSTLY ALTERNATE SOLUTION IS REEGIUALITY OF CHAMBER TO PROVIDE A LIMITED INCREASE IN THE SOUND A SOUND PROOF AIR sCONDITIONING SYSTEM INS'ALLAT3 SON ;OF STRATEGICALLY LOCATED SONAR PANELS IN CEILING AND ON WALLS. REPLACE OBSOLETE AMPLIFIERS. v REPLACE MI CR0'PIiONES WITH NOISE CANCELLATION MICROPHONES. v USE LAPEL MI;R�C-O'P:HONES FOR CITY COMMISSIONERS., EBALACITY MANAGER AND ADMINISTRATION 'To INSURE A QUALITY SOUND LEVEL AND SOUND CRORHONE 'SWITCHING UNDER CITY CLERKISCONTROL. ON —OFF PODIIIM;MI ., � �S FOR ;S,PECIAL .PRESENTATIONS CONTROLLED THRU PODIUM MICROPHONES USE LAPEL I9I CRORHONE REPLACE SPEAKERS IIANGI'NG FROM LIGHTFIXTURES WITH COAXIAL SPEAKERS NIO'UNTED ON °COMMISSION �CONSOLEFACING SPEAKERS AT .EACH COMMISSIONER'S POSITION, CITY MANAGER, AND ADD SMALL DESK ADMINISTRATIVE POSITIONS. v USE EXISTING LARGE SPEAKERS. 0 ESTIMATED COST — UNDER '$10.000. MtV -6P MIAM1; PLdlft1[)A NM4-OKPitt MM514ANbUM Assistyaht City MahAget �F+oM Ployd doubtrt Assistant Director CoYrImuiiications Services Div. bAtt May 6 i 1981 PILE §U11ACt Sound Evaluation of City Coifiinissiohet's Charnbers: RLrtitENcts IENCLO5UREr. The CoinmunitAtions Services bivisioh of the Department of Comput- ers and Communications conducted surveys of Commissioner's Cham- bers to evaluate sound problems within the chambers. The objec- tives are to define the existing problems and recommend the ap- ptopriate solutions. The two princip.l.e factors contributing to sound problems (are).the acoustical characteristics of the cham- bets and the public address sound system. CHAMBER ACOUSTICAL CRARACTERISTICS The Sound quality within the Commissioner's chamber is seriously degraded because of facility characteristics. Extra high ceil- ings, concrete walls, open areas and air conditioning, all con- tribute to excessive background noise and acoustical interference. An ambient noise measurement of 68 db was recorded in the center of the chamber, when it was empty. The normal voice level in quiet area is approximately 70 db. It is conceivable that in an audience environment, individual conversations would be at ap- proximately 80 db to overcome background noise and audience noise. All these factors increase ambient noise level within the chamber, without the sound system being turned on. Once the sound system is initiated, this background noise is amplified through open mi- crophones, which adds additional ambient noise to the chamber environment. Net result is that amplifier gain must be increased to overcome the ambient noise level within the chamber which causes the sound system to become more subsceptible to feedback and distortion. Further tests indicated that the air-conditioning system signifi- cantly contributes to the background noise. The rush of air through vents and fan motors adds approximately 10 db of noise as the noise measuring instrument is moved toward the air- conditioning equipment and vent locations. Both podium microphones are turn on during Commission meetings, which is another factor contributing to ambient noise. In addi- tion, an average of four of the microphones on the Commissioner's consoles and City Management area were inadvertently left on at various times during the last Commission meeting while someone was speaking. C�l -479 i May 61 1081 All the above fadtots donttibute to the degrading quality of sound afid atoustical thatadtetistits within the Comfiissionet's chafftber: The following tddotitfiendations offet alternatives to indtease the sound 4uality, within the Coot(hissionef's Chatibets. ty 1hbrdasing the signal to noise fdtio. l.AL The ultimate solution to the acoustical problem within the City 06mit19tio1iet's Chambet, is a thajot modifidatibb. to the fa- diiity. This would involve installation of a false ttiling with acoustical Absorption tiles, tlosing in all open areas/walls, new cafpetingo use of sound absotption material on concrete walls and installation of doors at the entrances. A new distributed air- conditioning system would be required. This approach is extretiely Costly and a decision to impletnent this recommendation would dew Pend upon the planned future use of this facility as a Cotnmis= sioner's Chamber. 2.= An alternate to recommendation #1 is partial solution to the acoustical problem. This involves replacement of present air vents with silent air vents. New belts 'be installed and adjusted on the airy -conditioning equipment. --Sound proofing of the air- conditioning room is advised. Background air-conditioning noise could be reduced by a factor of 30:o by implementing these recom= mendations. Approximate cost for material is $600. 3.- Background acoustical interference can be partially decreased by the installation of strategically located sonar panels. These panels absorb sound interference and act as sound buffers. Panels come in various colors and can be cut to fit walls or be suspended from the ceiling. Cost per six foot panel is $70. Approximately twenty (20) sonar panels will be required, resulting in a total cost of $1,400 for material. SOUND SYSTEM The existing public address sound system in the Commissioner's chamber does function, but has some problems. These problems consist of an obsolete amplifier, wrong type microphones, noisy speakers and improper placement of speakers within the chamber. The following are recommendations of the Communications Services Division: 1. - Replace the two obsolete amplifiers. Present amplifiers are noisy and have power hum. Maintenance has become a problem with these 12-15 year old 'vacuum tube type amplifiers. 2. - The microphones, especially the podium microphones, should be replaced with noise cancellation microphones. It is also recommended that lapel microphones be used by the City Commis- sioners, City Manager and City Attorney. This would insure a quality sound level and balance of sound for the more frequent users of the sound system. As a back-up to the lapel microphones, anti -noise microphones should be installed. Podium microphones should be switched by the Clerk of Court. This will minimize the amount of noise going through the system. . �. .... ..4 ♦ ..,h. ... .... ... .. .�,� ..-. '.Y'::'Vc w h..'a?•cWt'4�,ai�,.Meznw.r'wv 'w*gp4+MtWF...igl.. N e li-plideffidtit of the MIlAll tk I s t i fig noisy s; pe dke t s which presently hang ftbrn the light f ix t tit e t i With d6Akibl §PeAkdt§ mounted 6h the Corhtiggi6fiet'b consoles facing the Audi eritet Add trnAl I deck top IhdiVIdUAl 9PtAkdf§ in ktbfit of each Cdfftibib9i6ftdti City Mdfidgetj City AttortitY and Clerk of Court p6titibfits The two existing large speakets will be positioned to provide better sound d6kletages COST t8tIMATtg The recommended changes to the sound system should ihctedge ovet- a 11 sound duality by a factor of 10%, assuming recommendation #2 for the acoustical problem is acted upon. Some existing speakers, U-ki5tct dttg plifiert and existing witio will be used, The following is the cost estimate analysis associated With the above tetommen- dationst 1. 'Lapel Microphone (10 ea, at $80,) $ 800 2, Anti -Noise Microphones (11 ea at $165.) $1,815 1. Dual Amplifiers (2 ea. At $100) $Io400 4. Coaxial Speakers (8 ea. at $40,) $ 320 5. Small Speakers (12 ea. at $20.) $ 240 6, Mixer Pre -amplifier $ 420 7. Mounting Hardware/wire $ 260 8. Outside Labor $ 690 SOUND SYSTEM TOTAL $5,945 Total for Acous tical—recommenda t ion and Sound System recommenda- tion are: 1. Air conditioning changes (materials) 2. Sonar Panels 3. Sound System T OTAL FJ/ac cc. Howard V. Gary, City Manager Bryce Genzlinger, Director, DCC Don Cather, Director, Pub. Works Wm. E. Parks, Asst. Director, Pub. Wks. $ 800 $1 400 $5,945 $8, 145 k9l -479 I 5 i 7 f SOUND SYSTEM EVALUATION t FOR R CITY COMMISSION CHAMBERS a { PREPARED BY: FLOYD JOUBERT DEPT. COMPUTERS & COMMUNICATIONS COMMUNICATIONS SERVICES DIVISION PAGE SYSTEM EVALUATION L JVTiR0DUCTIiON PURPOSE INVESTIGATE SOUND SYSTEM PROBLEMS IN CITY COMMISSION CHAMBERS DUE TO COMPLAINTS BY CITY OFFICIALS OF POOR SOUND QUALITY DURING CITY MEETINGS. OBJECTIVES DEFINE EXISTING SOUND SYSTEM PROBLEMS RECOMIMEND SOLUTIONS AND ASSOCIATED COSTS EVALUAT10-N APPROACH CHAMBER ACOUSTICAL CHARACTERISTICS PUBLIC ADDRESS SOUND SYSTEM PAGE 2 SORID SYSTEM EV .LU ,T I 0 ' 2.1.0 EXISTING SOUND SYSTEM PROBLEMS „ ANY !FACTORS CONTRIB'UT;E TO SOUND GIUALITY WITHIN THE CITY COMMISSION CA MBERSACTERISTIC Tk10 PI?iiVC3PAL FACTORS CONTRIBUTING TO SOUND PROBLEMS ARE THE ACOUSTIC DP THE r-HAM$E'R AND T,HE PUBLIC .ADDRESS SOUND SYSTEM. 2.1 ACOUSTICAL CHARACTERISTICS f:AaLITY ,'UNSTRUCTION I I.GH .CEILINGS EXPOSED CONCRETE MALLS s1 - PARTIAL MALLS OPEN AREAS AND No DOORS o NO3'SY AIR CONDITIONING SYSTEM 0 LACK OF ACOUSTICAL ABSORTION MATERIAL (CARPETS, CURTAINS, CEILINGS, AND SOUND BAFFLES) TO :REDUCE BACKGROUND ACOUSTICAL INTERFERENCE. 2.1 PAGE 3 aO� MLEM EM ACOUSTICAL {CHARACTERISTICS (CON 'T) pTy Chi CR NOISE ! 'EVE S a 6$ DB ;OF AMBIENT ;NOISE ,LEVEL MEASURED AT CENTER OF CHAMBER. AIR CONDITIONING SYSTEM IS A MAJOR CONTRIBUTOR TO THE AMBIENT ISNOISE MOVED LEVEL- NOISE LEVEL INCREASES TO 76 DB AS MEASURING INSTRUM ENT TOWARDS THE AIR CONDITIONING EQUIPMENT. AMBIENT NOISE .LEVEL .OF CHAMBER INCREASES FROM 10 TO 14 DB WHEN THE SOUND SySTEM IS TURNED ON BECAUSE OF OPEN MICROPHONES WHICH AMPLIFY THE SIANDNG -NOISE LEVEL OF THE CHAMBER. OPEN MICROPHONES EXISTS IATBOTH POD THOSE THAT ARE INADVERTENTLY LEFT —ON AT COMMISSIONER S DESK. AMPLIFIER :HUM ACCOUNTS FOR AN ADDITIONAL 3 DB OF NOISE WITHIN THE CHAMBER. NORMAL D I.ST 1 INGUISHABLE 'VOICE CONVERSATIONS BETWEEN TWO PEOPLE RANGE BETWEEN ,o 3 AND j DB ABOVE THE ,AMBIENT ENVIRONMENT NOISE LEVEL. AS MORE PEOPLE NOISE INTO CONVERSATIONS WITHIN THE AUDIENCE AN OVERALL AUDIENCE.INCREASE OF AMBIENT RESULTS ,WHICH IS A FUNCTION OF THE SIZE OF THE AUDE PAGE 4 SOUND SYSTEM E. V�L_L'A IDP! 2.1 AC,0USTICkL CHARACTERISTICS (.CON'T) AIDIENCE iCONTRIBUTED NOISE DURING !MEETINGS, AUDIENCE NOISE LEVEL INCREASES DUE TO SMALL GROUP , _C,oN RSATION'S, HALLWAY MEETINGS, AND AMBIENT NOISE. TOTAL NOISE OF 35 TO 35 DB CAN BE EXPECTED. AMPLIFIER GAIN IS SET TO OVERCOME THIS NOISE LEVELWHICH CAUSES THE SOUND SYSTEM TO BECOME MORE SUSCEPTIBLE TO _ FEEDBACK ;AND DISTORTION. A OPEN MICROPHONES FURTHER DEGRADES THE SOUND SYSTEM. EXISTING.MI'CROP.HONES ARE NOT NOISE CANCELLATION TYPE WHICH ARE USUALLY SPECIFIED FOR USE IN THIS ENVIRONMENT. 2 PAGE 5 SOUND UY5STE . EVALUATION 2.2 PUBLIC ADDRESS SOUND SYSTEM TIlE EXISTING PUBLIC SOUND SYSTEM DOES FUNCTION, BUT HAS THE FOLLOWING PROBLEMS: o OBSOLETE AMPLIFIERS (HUM AND DISTORTION) .o WRONG TYPE MICROPHONES iNOISY SPEAKERS IMPROPE°R PLACEMENT OF SPEAKERS CAUSING DEAD SOUND SPOTS WITHIN CHAMBERS is LA PAGE 6 SOUND S S EM E U TI00 3.0 lRECoMMEVDATI oNS./ 0STs VES TO INCREASE THE SOUND QUALITY LOWING RECOMMENDATIONS OFFER ALTERNATI THE FOLLOWING -WITiHgN T+jE COMMISSION CHAMBERS. II Ti . SO 17TIO THIS RECOMMENDATIONREQUIRES A MAJOR FACILITY MODIFICATION WHICH INCLUDES: INSTALLATION OF FALSE CEILING WITH ACOUSTICAL ABSORBTION PANELS z NEW CARPETING v IJSF Of SOUND ABSORBTION MATERIAL ON HARD WALLS ELIMINATION OF ALL OPEN AREAS o INSTALLATION OF SOUND :PROOF DOORS „, INSTALLATION OF LOW EFFICIENCY SPEAKERS IN CEILING VEW 'SOUND SYSTEM REPLACEMENT OF MICROPHONES ,o JfEW DISTRIBUTED AIR CONDITIONING SYSTEM ESTIMATED COST - $75,000 I PAGE % SOU aD S ST M V U . IO 3.0 RECOMMENDATIONS-kOST '(.COST'T) AL TERIVATE SOLUT ION A LESS COSTLY ALTERNATE :SOLUTION IS RECOMMENDED. THIS IS A PARTIAL SOLUTION TO PROVIDE A LIMITED INCREASE IN THE SOUND DUALITY OF CHAMBER, 0 SOUND PROOF .AIR CONDITIONING SYSTEM OF STRATEGICALLY LOCATED SONAR PANELS IN CEILING AND ON WALLS. a INSTALLATION REPLACE OS'SOLETE AMPLIFIERS. 0 REPLACE MICROPHONES WITH NOISE CANCELLATION MICROPHONES, 10 USE LAPEL MIRCORHONES FOR CITY COMMISSIONERS, CITY MANAGER AND ADMINISTRATION TO INSURE A QUALITY SOUND LEVEL AND SOUND BALANCE. ON -OFF PODIUM MICROPHONE SWITCHING UNDER CITY CLERK S CONTROL. AF USE LAPEL MICROPHONES FOR SP:E.CIAL PRESENTATIONS CONTROLLED THRU PODIUM MICROPHONES. REPLACE SPEAKERS HANGING .FROM LIGHT FIXTURES WITH COAXIAL SPEAKERS. MOUNTED SON COMMISSION CONSOLE FACING AUDIENCE, ADD SMALL DESK SPEAKERS AT EACH COMMISSIONER S POSITION, CITY MANAGER, AND ADMINISTRATIVE POSITIONS. USE EXISTING LARGE SPEAKERS, ESTIMATED COST UNDER �10,000.