# Sound files¶

The currently only support format for sound files is .wav. Sound files must adhear to the following conditions:

Note

Sound files will be ignored if there is no .lab or .TextGrid with the same name as the sound file. The aligner will print a warning message when this happens and log all such files.

## Sampling rate¶

Sound files can be aligned regardless of their sampling rate so long as it is more than 16 kHz. Sound files to be aligned do not have to be all a single sampling rate, but each speaker must have a consistent sampling rate across their files.

Note

Sound files with sampling rate lower 16 kHz will currently be ignored by the aligner. The features that the aligner extracts are MFCCs dervied from spectra from 0 to 7.8 kHz, so sound files must have Nyquist frequencies higher than 7.8 kHz. There is no difference between the features derived from a sound file sampled at 16 kHz and one sampled at 44.1 kHz. Any ignored files will cause a warning to be printed to the console, and the list of such files will be available in the aligner’s log.

## Duration¶

In general, audio segments (sound files for Prosodylab-aligner format or intervals for the TextGrid format) should be less than ~ 30 seconds for best performance (the shorter the faster). We recommend using breaks like breaths or silent pauses (i.e., not associated with a stop closure) to separate the audio segments.