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Applying Advanced Audio Technology in Courtrooms

Good sound is hard work

Justin O’Connor

Audio is a critical element of any court trial, and the technology has come a long way in just a few short years. Today’s judicial facilities rely on sophisticated audio equipment for everything from surveillance and security to depositions to capturing witness testimony in trials. Courthouse audio requirements vary widely according to the size of the facility, the types of court proceedings that are conducted, the types of content that will be considered admissible as evidence and the age and condition of the courthouse.


Electronic equipment has been used in judicial settings for many decades, but until the digital revolution, the use cases were fairly rudimentary. In the beginning, audio was all about local sound reinforcement to make sure everyone could hear everyone else in a large courtroom. Installers used analog mixers, and the most complicated decisions they had to make centered on where to install microphones and speakers given a particular hearing room’s acoustics.

The emergence of professional recording equipment opened up possibilities for recording not just trials but hearings and depositions taking place outside the courtroom. This was followed by advances in telephony and conferencing equipment that began to enable remote testimony from witnesses who couldn’t attend the trial in person, or from defendants who couldn’t be moved for security or other reasons.

With the expansion of high-bandwidth IP networks and high-resolution Internet communications, the role of AV in the courtroom―and the supporting technology―has undergone a sea change. Hardware-based conferencing equipment has given way to software interfaces running on commodity computers. Most significantly, courtroom testimony has become a reflection of the driving role that digital content now plays in our day-to-day lives.

If we carry around a smartphone or tablet, most of us create a daily digital record of our lives, and much of that content is now admissible as evidence in many court trials. Phone calls and voicemails, YouTube videos, other social media content and smartphone photos are just a few examples. For litigators to effectively present their case, they need robust and easy-to-use systems for playing back this evidence.


The biggest challenge lies in deploying systems with two often-opposing qualities: highest-quality output and the simplicity to enable system operation by even the most untrained user. Pristine audio quality inside the courtroom is especially important when the content itself is less-than-ideal; for instance poor bandwidth between two sites for remote testimony, or the broken sound of a poor cellular connection in a recorded phone call.

Although the in-house audio equipment may not be able to improve these quality issues, it absolutely cannot add to the problem; therefore, the technology should be of the highest caliber. And we can’t overstate the ease-of-use requirement, since there’s typically no on-site expert in the courtroom to operate the systems (exceptions are high-profile cases with TV media coverage).

Meeting these requirements is not difficult, but it requires installers with a strong understanding of acoustics and audio best practices, such as good gain staging, microphone placement with local sound reinforcement, and perhaps mix-minus for appropriate gain. Equipment based on digital signal processing (DSP) is crucial for delivering the performance, control and sound tailoring that will ensure that everyone in the room is not just hearing the testimony, but understanding it. Another key technology is acoustic echo cancellation (AEC), which improves teleconferencing sound quality by preventing recirculation of reflected sound waves (aka, echoes) in a conferencing or meeting environment. (See Figure 1)


The most important factor is to choose professional-grade audio equipment that’s capable of handling the high degree of interconnectivity needed in today’s typical courtroom. This means professional-level interfaces to everything from advanced teleconferencing equipment to a consumer or personal device connected for listening to audio evidence.

The good news is that software-based systems for getting audio into and out of devices have come a long way, particularly for remote video/audio conferencing. One caution we’d give is not to yield to budgetary pressures and rely on free Internet services such as Skype or Google+, because the infrastructure and bandwidth are not at a par with paid services like Citrix GoToMeeting or Webex. Also, there are some exciting new technology translation tools, like those offered by Blue Jeans or Pexip, that provide a bridge between different services; i.e. a person using Webex on one end can communicate with a party using Citrix on the other end.

Another critical factor for the courtroom is networked audio. By centralizing control and management of distributed audio systems, network-based technology allows for more affordable and efficient deployments in large court facilities with multiple hearing rooms, offices and conference rooms.

Economies of scale are at work here―the more you can leverage a network topology across many different rooms, the less gear needs to be deployed for each room and the easier it is to upgrade and expand the system. (See Figure 2)


One scenario is a case or trial that doesn’t require remote witness testimony. Here, a simple DSP-based audio system interface can provide advanced capabilities for control and tailoring of the sound. Some might argue that audio systems aren’t necessary in this situation, but there’s still a need for sound reinforcement if multimedia evidence will be introduced, or if the court is making an audio recording of the proceedings.

Another interesting use case involves the requirement for a document camera in the courtroom. Here, the DSP system could act as a third-party controller for this and other non-audio equipment.

And, as we’ve mentioned, networked DSP systems can handle distributed audio in multiple courtrooms with the help of audio-video bridging technology, an IEEE open-standard networking protocol that allows media to be networked across Ethernet networks.


Bandwidth has always been important for audio and video quality, and it will continue to be the gating factor in remote teleconferencing for courtrooms. Legal professionals who have put up with dodgy quality in the past will continue to raise their expectations for courtroom audio, especially as they see quality continue to rise with other applications and services at home and in the office.

I believe we’re reaching a tipping point in which justice organizations will realize that the most inexpensive solution isn’t always the best, especially if it comes with a cost to audio quality, effective communications and a fair trial for the defendant. After all, there’s only a one-syllable difference between “guilty” and “not guilty.”

There’s another cost that’s a bit more insidious, and that’s the toll that poor audio takes on the judges, clerks, court reporters and other staff who spend all day, every day in the courtroom. Straining to understand what someone is saying can be tremendously fatiguing; even in the corporate world, we’ve found that concentration and focus plummets if the audio conditions are less than optimal.

Courts that budget for state-of-the-art professional-level equipment and a qualified designer/integrator to deploy it properly will not only save money in the long run, but will reap the benefits of a better and more productive working environment.

Justin O’Connor is the audio product manager for Biamp Systems. He can be reached at