Sound files 2.4. NeXT/Sun (.au) files

This is the format of the sound files on the Sun.

Reading

To read a Sound from a Sun audio file on disk, use Read from file....Praat then asks you for a file name. After you click OK, Praat determines the encoding of the file. If the encoding is 16-bit linear, the 16-bit sample values are divided by 32768 so that the amplitude of the resulting Sound is between -1.0 and +1.0. If the encoding is 8-bit μ-law, the 16-bit sample value is determined by table look-up first.

The resulting Sound will appear in the list of objects; its name will be equal to the file name, without extension.

Saving

Use Save as NeXT/Sun file.... The samples of the Sound are multiplied by 32768 and quantized between -32768 and 32767; the result is written to the file in 16-bit mono Sun audio format.

To avoid clipping, keep the absolute amplitude below 1.000. If the maximum sound pressure level is 91 dB (top = 32767), the quantization threshold is (top = 1/2) -5 dB.

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© ppgb, January 31, 2011