Audio Technology

Recording

Microphones

Introduction
Frequency response
Polar Patterns
Proximity effect
Cabling and phantom power

Recording techniques

Recording environment
Microphone placement
Signal processing and special effects

Pre-amplifiers

Recording devices

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

Processing

A-to-D conversion

Improving audio digitization
Digitization workflow

Analysis and Delivery

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

Audio Technology / Analysis and Delivery/ Digital restoration...

Often, linguists, oral historians, anthropologists, and educators find themselves dealing with old, noisy recordings. The digitization process itself does not improve the quality of the recording, nor does it remove any of its imperfections. However, there are a few simple DSP techniques that can be used to clean up and enhance the recording. The example below shows how several DSP techniques have effectively removed some of the unwanted noise from an old DARE recording. The original signal contained low frequency noise whose spectrum overlapped with that of speech, particularly around the f1 area. After the restoration procedures have been applied, the amplitude of noise has been decreased by over 20 dB, which separated it from the speech signal, thus making the file significantly more appropriate for reliable acoustic analysis (GRAPH>>).


Audio Technology
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