Managing The Acoustics In Our Connected World

The power of the internet allows global communication, either via peer-to-peer video or in group settings such as seminars, education or conferencing, writes Peter Janis.

Today, anyone – anywhere can plug in and communicate. But the question here is how well is the message you are transmitting actually being received? In other words, can your listeners at the receiving end actually comprehend what you are saying?

One needs merely to think of the last time you were in a noisy restaurant to conjure up images of frustration at not being able to communicate effectively with the person sitting across the table. Luckily, in some noisy and disruptive environments, we are at times able to somehow receive the message that is being transmitted, by combining our basic human abilities of lip reading, body language and the brain's unbelievable ability to block out unwanted noise. By combining all of this sensory adaptation we somehow get the picture even if we miss many of the words.

A microphone is different. A microphone is unable to discern the stuff we want to hear with the ambient noise, echo, reverberant field and other distracting conversations nearby. A microphone is not selective. It flattens out the signal to the point that the listener at the other end of the wire is unable to accurately hear what is being said. Broadcasters have known this for years and as such, acoustically treat their studios with absorptive panels to eliminate the reverb and then make sure the broadcast environment is perfectly quiet.

The science itself is simple: when you have a hard reflective wall surface, sound from the voice ricochets of the walls, floor or glass windows and competes with the original sound. This causes an effect known as comb-filtering, whereby, certain frequencies will amplify when combined 'in phase' and cancel out when 'out of phase'. The solution is to mount absorptive acoustic panels like the Primacoustic Broadway series to the wall surface to absorb and attenuate the reflections that cause first order reflections, flutter echo and the long reverberant trail. If you are in a post-production suite and editing program, you will want to mount panels on the side walls, between the speakers and the editor, in order to reduce primary reflections. If the room is small, placing panels behind the listening position is important. As a general rule, applying 25% wall coverage using 2" thick Broadway panels will help tremendously. These are made from high-density 6lb glass wool and provide even absorption down to about 350 Hz and are approved for safe use on both sides of the Atlantic!

Once your panels are up, if you notice excessive bass build-up or bass cancellation due to room modes, this can be controlled by mounting two or four Cumulus tri-corner bass traps up high – in the corner where the two walls and the ceiling come together. Voice-over booths are particularly bad when it comes to low frequencies as these small rooms tend to be treated with low-density foam that only absorbs high frequencies. This leaves the room sounding bass heavy – creating an effect that is often referred to as 'chest hump'. Cumulus traps will effectively remove bass down into the 100 Hz and help attenuate the dreaded chest hump in the 300Hz region.

The same general rules of communication apply to pod-casting, video conferencing and huddle rooms. Communication can be improved dramatically by simply adding Broadway acoustic panels to your room. Panel placement is not as critical as getting panels up on the wall. And considering the goal here is communication, it only makes sense that you improve intelligibility when attempting to do so.

Peter Janis is the president of Primacoustic, a division of Radial Engineering Ltd. The company began working with acoustics in the 1990s and counts a huge number of global clients including NBC-TV Olympic Broadcast Center, Cisco Systems, The Vancouver Convention Center, Meyer Sound laboratories and Renaud – the automobile manufacturer. Primacoustic is represented in the UK by Shure Distribution UK.

www.primacoustic.com

This article is also available to read at BFV online here, page 45.

(JP)