ClearOne: How to Get Better Audio on Your Conference Calls

By: Richard “Zippy” Grigonis

Using audio conferencing equipment is one of the easiest ways for organizations of any size to save money, reduce their carbon footprint, and boost productivity. And today’s high-definition conferencing technologies make group communications possible in a very natural, effective environment. But a conference call with bad audio is more than just annoying. Bad audio leads to participants experiencing “listener fatigue”; they don’t fully engage because they can’t hear all of the conversation; important ideas aren’t fully explored because comments aren’t understood.

But it doesn’t need to be that way. In search of tips in this area, Yours Truly spoke to Mark Child, Director of Product Marketing — Telephony for ClearOne (News - Alert), masters of high performance audio conferencing. Here’s what he suggests you can do to maximize the experience and make your conference calls more effective and rewarding.

RG: How do I get rid of the echo?

MC: If a conference phone doesn’t do a good job of acoustic echo cancellation, a conference participant can often hear his (or her) own voice coming back through his loudspeaker, but at a slight delay. This echo makes it extremely difficult to carry on a normal conversation. Effective echo cancellation can identify the audio from my microphone that is being returned to my speakerphone and cancel it out — completely.

RG: If I’m in a noisy room, is there any way to improve the sound quality?

MC: Yes! Almost all rooms — including most conference rooms — contain ambient noise, produced by HVAC systems, fluorescent lights, projectors, computers, etc. Noise cancellation algorithms can identify these sounds and remove them. The best conferencing phones use a digital analysis technique that discriminates the talker’s voice from ambient room noise and cancels the noise. This allows the conversation to pass to the far side in a pristine condition.

RG: What does “full-duplex” mean?

MC: Full-duplex simply means that the audio is two-way. In other words, call participants can both talk and listen at the same time. Many devices claim to be full-duplex but really deliver only half-duplex performance. This means that when one person is talking, he cannot hear anything being said from the far side without substantial audio clipping or suppression.

RG: Why does it sometimes sound like I’m in a tunnel?

MC: When multiple microphones are active simultaneously, voice signals arrive at different microphones at different times due to sound reflection from walls, ceilings or other surfaces. This causes sound distortion often described as a “hollow” or “tunnel” sound. Such distortion can be minimized or even eliminated by phones that use an intelligent voice detection method to activate only one microphone at a time based on the proximity of the person doing the talking.

RG: Sometimes the audio starts out okay, but then it suddenly worsens. Why?

MC: In any conferencing environment, a number of factors can cause changes in the room’s ambient noise level, including the HVAC system cycling on and off, an increase or decrease in the number of people in the room, changes in seating arrangements and other similar acoustical events. This can often cause feedback or residual echo. Some conference phones use a type of “adaptive modeling” technology to continuously monitor key acoustical elements in order to predict and adapt to environmental changes, ensuring high quality audio, regardless of varying room dynamics.

RG: Why does the audio sound really tinny, sometimes?

MC: The vast majority of conference calls are conducted using narrow-band phone signals, which eliminate the high and low tones from your voice. This often causes listener fatigue since participants have to strain to hear what is being said. Technology is available that can simulate the high and low tones that were eliminated, creating a more full-sounding audio even from a narrow-band phone signal. This makes the call sound much more natural and easier to listen to.

RG: Does it really matter where I place the conference phone?

MC: Yes, it does. For example, in a medium- or small-sized conference room, a tabletop conference phone should always be placed in the center of the table. This makes it possible for all participants to hear and be heard. This also helps the phone effectively handle feedback or residual echo from reflective surfaces. In other words, don’t place the phone up against a wall or window and expect it to sound good.

RG: Anything else?

MC: Just remember that in order for the microphones to work effectively, they should have plenty of empty space around them. Be careful that papers or notebooks don’t accidentally cover up any of the microphones. And if participants are tapping on the table or playing with the equipment, the extra noise can cause the digital signal processors (DSPs) in the phone to go through a lot of extra gymnastics in order to try and differentiate between the extra noise and the speaker’s voice. IT

» Internet Telephony Magazine Table of Contents