Audio Considerations in Teleconferencing – “Can You Hear Me?”
Teleconferencing, holding meetings by an electronic means, is one of the fastest growing industries in the world. The word “teleconferencing” means different things to different people. Teleconferencing can range from a conference call with speaker phones to a system with installed overhead speakers and tabletop microphones, to a full scale audio for video conferencing system with satellite feeds.
Regardless of the type of teleconferencing, how the audio portion of your conference is handled will ultimately determine the success of the system and satisfaction with the event. Every meeting starts with “can you hear me?” or thud, thud, thud as a person taps a hand on the microphone.
Remember the last time you went to a movie where the theater had problems with the soundtrack? It’s the same with teleconferencing. Even if you have perfect video, audio problems will destroy the conference. One of the biggest problems in teleconferencing is background noise. When you are in a conference or meeting room and you hear background noise such as duct rumble, diffuser noise, or a computer fan, you for example, individually, tend to block out or ignore the noise because you have been able to identify its source. In a teleconference, however, this background noise is transmitted to the distant location along with the sound of your voice. There is no longer a method for the listeners at the other end to distinguish where that noise came from. The noise becomes distracting and masks over the spoken word.
The proper acoustical treatment of any room with teleconferencing is extremely important to the success of that conference. If more than one microphone is used, it is also very beneficial to have an automatic microphone mixer that limits the number of microphones that are active and turns on the microphone nearest to the person speaking. If the only active microphone is the one closest to the person speaking, the intelligibility of the conference will be much higher. Ceiling-mounted microphones contribute to the attractiveness of the conference room, but at the other side of the conference, it sounds like the participants are not talking into the microphone.
The further someone is from the mic, the greater the chance that background noise will drown them out. The best idea is to place the microphones close to the people speaking.
Another source of trouble in teleconferencing is the phenomenon known as “acoustic echo”. Acoustic echo appears when the conference room is operating with open mics and loudspeakers in full duplex conference mode. A full duplex conference mode is when you and the distant room can have a one-on-one communication without having to wait for the other room to stop talking.
Electronic audio signals are sent in both directions simultaneously. In this situation, your audio goes over the transmission media to the speakers in the distant room. The audio is then picked up by the open microphones in that room and retransmitted to you. The result is that you will hear your own voice coming back to you from the far room, thus the echo. This effect is similar to talking over a public address system in a stadium — highly confusing.
Fortunately, acoustic echo can be minimized. It is very easy to remedy the problem by installing an acoustic echo canceller. An echo canceller looks at the audio coming into the room from the loudspeakers, and compares it to the audio from the microphone. Any audio that “matches” is removed from the transmission. However, to keep your installed in the distant room. This means that you will need an echo canceller in every room that is part of your conference. Remember, an echo canceller compares the audio from the loudspeakers to the audio from the microphones. Your best bet is to put an echo canceller in each room. This will assure that none of the rooms can create an echo condition.
Teleconference equipment can be easily installed in existing conference rooms. The best test for proper operation will be made with everyone’s ears. And don’t forget the audio.