Audio Technology

Recording

Introduction
Frequency response
Polar Patterns
Proximity effect
Cabling and phantom power

Recording environment
Microphone placement
Signal processing and special effects

Introduction
Analog recorders
Digital recorders
DAT recorders
Minidisk recorders
PC card and CD-R recorders
Hard disk recorders

Processing

Improving audio digitization
Digitization workflow

Introduction
Preparing files for analysis and delivery
Digital restoration
LPC in acoustic analysis

Audio Technology / Recording techniques/ Microphone placement...

Microphone placement

The placement of the microphone directly affects the intensity of the recorded signal as well as the signal-to-noise ratio. The inverse square law guarantees a loss of approximately 6 dB per doubling of distance from the sound source. A typical handheld microphone is usually placed at a distance of 30 cm or so from the talker’s lips. This, relative, to a close placement (say, 4 cm) represents the loss of about 18 dB and an increased possibility of noise leaking into the recording. For this reason, it is recommended to use a head-mounted condenser microphone (such as AKG C410 or AKG C420) to maintain a close, and constant distance to the source. Speech signals acquired this way are characterized by a high SNR and a broad range of intensity. It may also be useful to use a linear phase high-pass rumble filter (60 Hz cutoff and 24dB/octave attenuation), unless low-frequency components are expected in the signal.

Audio Technology
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Last updated: 2002