Selecting Microphone Locations

The golden rule

The golden rule of microphone placement still exists. You want to place the mic as close to the subject speaking. Fortunately, recently technology has enabled us to break this rule from time to time. We are all used to seeing microphones on a conference table and at the podium. But what if we could place the table mic elsewhere. What if we did not have to worry about the user mic technique and could just focus on the video call? Can we build the microphones into the aesthetic design of the room?

The shotgun approach

For years the film industry has been using shotgun microphones to pick up audio from a distance. Shotgun microphones employ a very narrow pickup pattern and are designed to reject unwanted sound, not within the pickup pattern. Using this same approach, we can move the microphones in the conference room toward the screen or even the ceiling. Advancements in acoustical echo cancelation allow us to feed a reference signal into an algorithm which cancels out any audio coming from the near end speakers. In some cases, having the mics closer to the speakers helps the algorithm do its job.

Tracking

All microphones have what is called a polar pickup pattern. Basically, it’s the area of the microphone that pics up sound. To decrease background noise, we can “turn off” areas of the pickup pattern with software. This allows us to “track” vocal energy from a specific point in the room. This process is a constantly changing equation that is always looking for the clearest and loudest energy.

Acoustics

What we cannot fix with microphone placement and software are the natural acoustics of the room. Sound is either reflected or absorbed by a material. If our room has many reflective surfaces, the sound tends to ping-pong around for a while as if in an empty fishbowl. However, if we were to add enough absorptive material, we can lessen the bounce of soundwaves and give our audio system some assistance. Remember, the microphone and digital signal processing need to be able to determine the difference between the far end presenters and the near end. Any change to the room acoustical dynamics, i.e. someone enters the room, or a door is opened, causes the processor to work harder to capture true line-of-site energy. Proper acoustical treatment can go a long way to achieving better audio. So, can we place the mics on the table? Yes. Can we place them in the ceiling? Yes. Natural sound reproduction is an art. With the right balance of room acoustics, digital signal processing, and mic placement, we can achieve great results.

At Better Building Solutions, we live on the cutting edge of audio reinforcement solutions. Our expertise and experience bring you the right product and deployment to enhance your collaborative experience.

Author: David Warren
Loading - Please wait ...