Microphones have a tremendous impact on sound quality, and different spaces require specific equipment in order to optimize clarity. Think, for example, of a corporate boardroom that accommodates 20 executives, versus a 500-seat university lecture hall.
Regardless of type or intended function, all microphones are transducers – devices that convert one type of energy into another. A microphone is a transducer that converts sound (acoustic energy) into electric energy. There are many varieties of microphones available, but dynamic and condenser microphones are the two most common types used in the AV industry.
Condenser microphones have higher sensitivity, excellent transient response, and superior frequency response. These microphones can be small and lightweight, but require a power source in order to function. Condenser microphones are available in Electret and Externally Biased models. Electret refers to the back of the microphone cartridge being permanently charged, with external power required for the impedance matching circuitry. Externally Biased microphones have external power for both the impedance matching circuitry and to charge the back plate of the condenser capsule. Powering condenser microphones involves phantom power (a DC electric power transmission method), which is supplied by a mixer or external phantom power supply. Available power ranges from 11 to 52 volts, though 48 volts is standard. Phantom power requires a balanced connection. It uses the same wires that are used for audio, and will not damage dynamic microphones. In the AV industry, most microphones are Electret.
When selecting a microphone, shape and function (form factor) are important. Form factor refers to the way a microphone’s shape adapts to its intended use. Multiple shapes and designs are available to suit the user’s needs and circumstances. These include:
- Size, weight, and feel are the primary decision factors
- Moves with the source
- Ideal for standing speakers or singers
- Can be placed on a microphone stand
- Quality and level depends on user’s understanding of proper microphone techniques
- Size and appearance are critical decision factors
- Maintains set distance from the source
- Ideal for talkers, singers, and presenters
- Requires minimal experience with proper microphone techniques
- Available types:
- Instrument clip
Installed (Away From Surfaces)
- Appearance is important
- Used in permanently installed applications
- Appropriate for seated or standing speakers
- Ideal for meeting rooms, boardrooms, and podia
- Requires minimal experience
Boundary (Installed on Surfaces)
- Mounted directly on surfaces
- Visually unobtrusive
- Ideal for boardrooms and meeting rooms
- Appropriate surface is critical for proper functionality, as placing objects near or on top of the microphone can interfere with its ability to pick up signals
The dimensions of your space, the needs of your speaker(s), and the size of the audience will help you determine the appropriate type of microphone. For example, a college professor teaching a popular sociology lecture might favor a headset microphone, which will allow her to move around the classroom and interact with students. A corporate board member would be more likely to opt for an installed microphone on a podium or tabletop. An experienced singer would do well with a handheld microphone. Choosing the appropriate microphone can make the difference between speaking and being heard. To learn more, check out our Audio 101 video series on microphones.