Sesam/LVS files

A way for storing a Sound object on disk.

File format

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, August 28, 2017