It is a fundamental principle in acoustic analysis that any waveform, however complex it might be, can be broken down into simple waveforms of different frequencies. The operation of doing this is called spectral analysis, and in some ways is rather like breaking down white light into the rainbow pattern of colours that make up its spectrum. In carrying out the acoustic analysis of speech sounds, we can discover much more by looking at the result of a spectral analysis than by looking at the original waveform that was captured by the microphone. This picture shows the result of the spectral analysis of the word ‘see’ that we have already looked at. This type of picture is called a spectrogram. At one time there was a fashion for calling such pictures "voice-prints", but this led to some very dubious claims being made about identifying people by their voices for legal purposes, and the name is not now used except (sometimes) by gullible journalists.

                                   s                                                        i:
          NEXT PAGE