Mics and Mic Techniques for Conferencing Systems
In our increasingly digital world, traditional AV departments are disappearing from organizations. In many cases, responsibility for these functions has fallen to IT. Nowadays, along with managing computer systems and networks, many IT managers are charged with delivering audio for a wide range of their organization's activities.
Although much of the audio world has gone digital, there's also no escaping the fact that the acoustic side of the equation—the input and output—is, inevitably, analog in nature. Just as audio pros have embraced digital technologies, IT engineers are learning to speak the language of sound. More often than not, networked conferencing and discussion systems present the first hurdle.
Intelligibility Is Key
First of all, sound quality is not an absolute term. It depends on context. Good sound is different for speech than it is for music. Here's why:
Music is about fidelity. Achieving great sound quality in music requires the accurate reproduction of the entire frequency range of the instruments. The harmonious combination of fundamental and overtone frequencies can produce transcendent beauty, further heightened through reverberation within the room.
Speech, on the other hand, is about intelligibility, which is very different. The goal of intelligibility is the easy understanding of the words being spoken. Seems like that should be easy, right? Fact is, interference by unwanted sounds can have a profound effect on our ability to perceive speech accurately.
Ever tried to hold a conversation in an old, high-ceilinged auditorium? The time-delayed reflections that bring richness and majesty to music are the enemies of intelligibility.
Speech intelligibility is of primary importance in corporate, institutional and governmental environments. You want the CEO's speech to sound great. You want education sessions to be fully understood. The alderperson demands to be heard. Anything that interferes with the audibility of words in a meeting or conference is something that needs to be minimized or eliminated.
It Starts With The Microphone
A system's sound quality is only as good as its weakest link, so capturing quality audio at the source is essential. The microphone is still the starting point for that goal.
The primary types of mics used in meeting and conference rooms are stand-mounted and user-worn. Specialty types like surface-mount and hanging mics also are common. For vocal and speech applications, some design elements are universal. Most will feature internal pop filters and shock mounts to minimize unwanted noise. Size, shape, weight and feel are all important design considerations, too.
Even in the relatively stable world of permanent installations for meetings and conferences, it's difficult to provide a foolproof method for selecting the right microphones. The system that you're using—for example, a system that allows audience members to speak, versus a system appropriate for lectures, where there is one principal speaker—will dictate, to some extent, the type of microphone best suited to the task. While the basic principles are universal, different types of microphones require different techniques to prevent unnecessary problems.
How to Set Up and Use Microphones in Meetings and Conferences
Before the meeting starts, here are a few simple setup and use tips you can share with IT colleagues and speakers to boost intelligibility in any meeting or conference situation.
- Speak in a clear, natural voice.
- Aim the microphone toward the mouth and away from unwanted sound sources.
- Avoid excessive handling of the microphone, drumming on the table, shuffling papers, etc.
Now, let's look at the types of microphones you probably have in your conferencing or discussion system, plus some tips specific to each type:
- For a balanced, natural sound, position the microphone four to 12 inches from the mouth and slightly off-center to minimize breath noise.
- Being too close to a unidirectional mic causes a boomy sound due to proximity effect. This excessive bass can be controlled with EQ (low frequency roll-off).
- Speaking too directly into the microphone introduces breath noise. Use an accessory pop filter to control breath noise from close-talking speakers.
- Handle the mic only by its body. Do not grab or cup the microphone grille as this will compromise its directional properties.
- Place the microphone eight to 16 inches away from the mouth, slightly off center. Aim it just below the mouth to minimize breath noise.
- Once it is positioned for the talker, don't touch the microphone or its gooseneck mount.
- Maintain a consistent distance from the microphone for consistent volume.
- Don't tap on or blow into the microphone.
- Place the mic as close to the mouth as practical, preferably just below the neckline.
- Avoid placement beneath clothing or where anything may touch or rub against the microphone.
- Use a windscreen, especially with unidirectional lavalier mics.
- To stay "on mic," rotate the body rather than the head.
- Lavalier mics transmit even the subtlest noise into the sound system. Once you're wearing it, don't touch the microphone or cable.
- Avoid breathing directly into the microphone.
- Don't place the microphone directly in front of the mouth since it will pick up breath noise.
- Position the microphone just off the corner of the mouth, without touching the face.
- Use a windscreen to eliminate breath noise.
- Adjust the headband for a secure and comfortable fit.
- Don't tap on or hold the microphone.
There's a classic saying in computer science that applies equally well to audio: Garbage In, Garbage Out (GIGO). Computers require accurate data to produce reliable results the same way a sound system is only as good as the quality of the audio inputs it receives. A good place to start: using your system's microphones correctly.
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