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
/ Analysis and Delivery / Digital restoration...
