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A way for storing a Sound object on disk.
The sound files used by the SESAM and LVS programs. Each sample is normally quantized into 12 bits.
To read a Sound from a Sesam file on disk, use Read from file.... The file name is expected to end in ".sdf" or ".SDF".
The 12-bit sample values are divided by 2048 so that the amplitude of the resulting Sound is between -1.0 and +1.0.
The resulting Sound will appear in the List of Objects; its name will be equal to the file name, without extension.
If the sound was encoded in 16 bits per sample, you should divide by 16 after reading (with Formula... self/16)
With Save as Sesam file.... Praat then asks you for a file name. After you click OK, the samples of the Sound are multiplied by 2048 and quantized between -2048 and 2047; the result is written to the file in 12-bit LVS and Sesam format.
To avoid clipping, keep the absolute amplitude below 1.000. If the maximum sound pressure level is 91 dB (top = 2047), the quantization threshold is (top = 1/2) 19 dB.
If you prefer 16-bit encoding, you should multiply by 16 before saving (with Formula... self*16)
© ppgb, January 31, 2011