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Effective courtroom sound system design requires both knowing which participants need to hear whom at a particular moment and providing the technical


Oct 1, 1999 12:00 PM,
Gordon Moore

Effective courtroom sound system design requires both knowing whichparticipants need to hear whom at a particular moment and providing thetechnical insight to make it feasible.

As the world’s judicial systems grow in size and complexity, therequirements of courtroom sound systems keep changing to meet clerical,legal and procedural needs. When you are designing for federal, state,county or municipal facilities, you must be careful to address theprocedures and uses of that court.

One of the fundamental rights of any U.S. citizen involved in trialproceedings is the right to a proper hearing. The word hearing says it all.Deriving from the same roots as hearing in the sense of our auditoryresponse, this basic tenant of our judicial system demands that any actionsin a courtroom be clearly heard by all. When an amplified system is inplace, that system must meet several criteria. First, all persons speakingin the room must be picked up distinctly and clearly, which means enoughmics for all participants. Second, everyone in the room must clearly hearwhat is said. This means the loudspeaker system must provide even,intelligible coverage throughout the room. Feedback, static, crosstalk,phasing and other auditory distractions have no place here.

It also means that the design must take into account those needing hearingassistance and those who need to hear in other languages. Third, the systemmust be able to deliver the sound clearly enough to the parties who reportthe proceedings so that they may accurately reflect in the record the exactcontent of the trial. This applies to the press and the court reporters whoare the official keepers of trial records and transcribe everything thathappens in the trial. Finally, the system must take into account suchprocedural issues as sidebar conferences and grand jury hearings.

Mic choice and placement

Mics must be placed in such a manner that they cannot be covered oravoided. Avoid narrow pickup patterns that are too selective (watch asquirming witness under cross-examination). Cardioid gooseneck mics canimprove gain in almost all situations, but cardioid boundary layer mics canbe effective at the judge’s bench and witness box. The judges tend to moveabout a bit at their bench and can actually move out of the pickup patternof the mic if the pattern is too tight. Avoid hypercardioid mics at thebench, but, a supercardioid might be just the thing for the jury area.Their pronouncements are usually made strictly through the jury foreman whowill typically stand to address the judge. A highly directional mic placedhere reduces background noise generated by the jury. Also, be careful aboutplacement if you use a boundary mic. Many require a clear backfield; placedtoo close to the decorative molding rising at the front of the bench, youcould ruin its tonal quality and th!e related pickup pattern. Confer with the manufacturer before placing the mic. Fair warning on the judge’smic – ask about the design of the bench regarding where you can run yourcabling. Judge’s benches are bulletproof and may be tough to drill.

Mixing the mics in almost all courtroom designs today is accomplished withautomatic mixers, which do not require skilled operators. They can also belocked up, and some have remote control capabilities that allow integrationwith control systems. Mark Scheele, a court systems administrator for theU.S. District Courts in Albuquerque, NM, supports 10 federal courtrooms(designed by the Joiner Consulting Group, installed by New MexicoElectronics Systems) in his facility. He said that the automatic mixersreduce such environmental noise in the recordings as the sound ofattorneys’ holding private discussions at their tables, gallery (audience)noise and other distracting background influences. The mixers keepbackground levels consistent while capturing the active mics smoothly. With12 mics in a room, background levels would be nearly 11dB louder in the mixif a manual mixer with all 12 channels open were used.

The real trick in some courtrooms lies in gain control. The automaticmixers provide gain control because of their NOM (number of open mic)circuitry, but this is sometimes not enough. Poor acoustics of somepre-existing courts introduce real problems with gain. Beautiful hardwoodpaneling is elegant, but it lends itself to acoustical nightmares. Onesolution is a mix-minus design. Independent feeds to the judge’s bench,jury, prosecution, defense, witness and clerk with a mix-minus approach canreduce feedback and improve system performance. In a mix-minus design, theloudspeakers at the judge’s bench would carry the signal from all micsexcept the judge’s, and the witness would hear all mics from hisloudspeaker except his. Incorporating a matrix mixer into the design makesthis easy to accomplish and can add significant gain to the room.

The matrix mixer can also provide multiple feeds to a four-track recorderfor the recording process – judge and witness to channel one, prosecutionand jury to channel two, defense and clerk to channel three, and sidebar,podium and wireless to channel four. This selective recording process makestranscription of the tapes easier after the trial. The court reporter canrewind and play selected tracks back when the identity of the personspeaking is uncertain. Provide a combined feed as well. Scheele said thatmany court reporters have their own recording system and prefer to usetheir own instead of the installed multi-track system. In his federalcomplex, they have a separate jack they can tie into. Finally, the matrixcan provide press feeds to the Fourth Estate (the news guys in the back) sothat they can play back the audio on the evening news, if the judge allowsit.

Loudspeakers and amplification

“Everything you say can and will be held against you in a court of law.”For this part of the Miranda warning to hold true, the sound system mustdeliver clear audio to all participants, which means cleanly amplifiedsound. Address the acoustics first. All the laws of acoustics must be paidtheir due. Good loudspeaker choice and careful placement are critical. Deadspots are not acceptable in a court. For good intelligibility, thereproduced sound needs to be 20 dB to 25 dB higher than the ambient levelof the room, which includes the crowd noise, the air handlers and streetnoise. Fortunately, most new courtrooms are designed without outside accesseither by windows or doors. Architects and designers must make certain theair handlers are adequate to move enough air without sounding like a jetexhaust. Walls are getting acoustical treatment instead of cherry paneling.Ceilings are getting acoustical tile instead of drywall. See the picture ofthe Ontario courtroom project (pa!ge 56), and note the acousticalpanels on the walls behind the judge’s bench. The older courts lack some ofthese modern treatments, so whenever possible, address these issuesimmediately. You may need to add acoustical treatments or use carefulloudspeaker choice and placement to avoid unwanted reflections. Considermore loudspeakers at lower levels to provide even coverage throughout thecourt.

After assuring the listening intelligibility to the participants in thecourtroom, you will also need to address the issues of translation andauditory assistance. In federal courts and most county and municipalcourtrooms, translation in other languages plus a feed for English auditoryassistance will be required. First, a feed to the translator from thesummed mix of the mics is required. Then, the translators’ mic will have tobe fed to both a recorder and an IR or RF auditory assistance system. IR isthe more popular choice for courtrooms; frequency coordination is notrequired for IR, an important factor when setting up 20 courtrooms in thesame facility. The RF spectrum space will be needed for wireless mics. Auseful tip from Scheele in New Mexico: Have the users hang the IR headsetsbehind their heads instead of in front, which prevents their hands, tiesand clothing from interfering with the IR signal. They had a great deal ofdifficulty with the system until they beg!an this practice. A feed from the system to provide auditory assistance on another channel will also berequired.

You have now addressed making it so that everyone can hear, but what aboutthose times when the judge does not want anyone to hear? During federalproceedings (this also applies to many state courts), the sidebarconference (where the two attorneys confer at the bench with the judge) isconsidered a privileged conversation regarding procedural issues that arenot to be heard by the jury, witness or gallery. To prevent theseconversations from being overheard, the new U.S. federal standard has pinknoise injected into the room in all loudspeakers except the judge’s,thereby masking the conversation. A button labeled “sidebar” at the judge’scontrol panel activates this. The system must switch off all mics in theroom, activate the sidebar mic (generally an omnidirectional boundary miclocated on the rail of the judge’s bench) and route the signal to the courtreporter and the tape deck for transcription. The pink noise, which doesnot have to be really loud, prevents eavesdropp!ing. Remember, good intelligibility is predicated on a 20 dB to 25 dB level above ambient room level.Because the sound system will not be amplifying the conversation, themasking level needs to be only 6 dB to 12 dB above the ambient room level.Scheele reported that he had to turn down the pink noise after a few weeksbecause it was too loud. The original level was nearly the same as theamplified speech level.

Grand jury rooms present new problems, particularly on the acoustics side.Grand juries are anonymous, and their proceedings are privileged. Securityis a major factor. Not only must the acoustical treatments within the roomkeep outside levels down, but they must also keep inside audio fromescaping. Sealing doors and windows and keeping the level of the soundsystem to an effective minimum must be addressed. Specifying an auditoryassistance system allows the installer to preset or fix the levels in theroom so that the audio cannot be turned up loud enough to be heard outsidethe room. Anyone who cannot hear is issued a headset.

Other issues

Many courts now also incorporate video arraignments into their proceduresto increase security, reduce transport costs to and from jail, and to speedproceeding. An arraignment (the procedure to determine if a person is to bebound over for trial, (called a remand in Canada) is generally a shortprocess ideal for the videocon-ferencing world. Integration of the videosystem into the audio system requires feeds to and from the video codec. Insome courts, the video system may also be used for child abuse hearings andtestimony or remote depositions, which is especially useful when the personbeing deposed is incarcerated in another state.

The bench usually requires a sidebar button, a judge’s mic mute and asystem mute. The clerk or bailiff may also have room level controls.Finally, the facility administrator usually is trained to control theentire system back at the rack. The New Mexico federal courts have fixedlevels oneverything except the teleconferencing input and out levels andsome level control in the witness mic. The signal chain incorporates a DSPbox that equalizes and suppresses feedback. Scheele said that these keepthe system stable for all uses of the rooms. He uses the software includedwith his system components to fine tune the setup. The software controlkeeps the system access secure, and many courts use touch-panel controlsystems. Because many courtroom complexes must be used for various types ofprocedures, many systems incorporate components with memory presets thatpermit complex configurations to be readily changed according to the needsof the court. The changes may be complex, bu!t the act of changing must be as simple as pressing a button on a screen or switch panel.

The scope of the job is somewhat dependent on the court; a smallmunicipality courtroom will tend to be less complex than a federalcourtroom. Figure 1 shows a small municipal court similar to that found inRio Rancho, NM, in which eight mics, a simple mix-minus setup, noisemasking and a simple recording setup are incorporated. Figure 2 shows amuch larger complex with multimedia feeds, videoconferencing, noise maskingand a control system for switching room setup. If you have never designedor installed a court before, try to begin with a smaller municipal systemto familiarize yourself with the concepts. If, however, a larger systempresents itself early, do not back away. Federal courts in the UnitedStates and Canada are generally designed by such consulting firms asPolysonics, Electromedia Design or Joiner Consulting Group. Theconsultants, manufacturers and the courts themselves already havewell-defined concepts and designs for you to draw on. Working closely withthe! consultants and the systems administrators can ease the installation. William Scott of New MexicoElectronics Systems said that keeping the lines of communications open withthe system administrator and consultant makes all the difference. He spokeregularly with both six months before the installation. Take advantage oftheir expertise, and you will find the courtroom system interesting. Theprocess will also give you a much greater understanding of our judicialsystem.

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