Vocal Microphones for Classroom Recordings The Newest Technology

Published: 15th March 2010
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Recording a classroom in a large room can be challenging as sounds from the students, as well as background noise, often negatively impact the speech quality of the recording. New technology exists today that can overcome these limitations allowing for professional sounding recordings to be created without spending a lot of money.

A few years back a typical setup would require either a unidirectional microphone mounted on the podium or desk, or a lapel (lavalier) type worn by the instructor. The advantage to the desk setup is simplicity and excellent audio reproduction, the downside is that the speaker cannot move around, as the audio quality is impacted by how far the speaker is from the proximity of the microphone.

A wireless lavalier (or lapel) microphone allows the instructor to be mobile, but the disadvantage is that the speaker is the only one recorded. Omnidirectional polar patterns are available for lavalier microphones, but the depth of field is greatly reduced to eliminate ambient noise. This makes it virtually impossible to capture audio from the audience.

Traditional ways to get around these limitations would include having someone walking around with a wireless mic to field student questions, or to install an array of microphones. An array is essentially a group of vocal microphones working together, placed strategically throughout the room. These mics would then be attached to a computer so that the signals can be collected and assembled into a coherent form. This is a good solution in that the entire classroom can be recorded, but there's a tradeoff in the cost and complexity of the setup.

The newest "array microphone" technology addresses these limitations. It's now possible to have a number microphone elements working in tandem and physically located in a single device. The result is a "virtual array" of microphones. Given the fixed position of each element, digital signal processing (DSP) algorithms can isolate each signal source can create complex virtual polar patterns that provide the ability to zero in on, or to reject particular sound sources from around the room.

This is a great choice for classroom recording as these types of microphones can find and isolate a moving speaker, while filtering out background noise like air conditioning that is typically present in classroom settings. One example of a microphone that uses this
technology is the Vocal Microphone Store



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