pitchmark

Table of Contents

• Examples

Find instants of glottal closure in Laryngograph file

Synopsis

`pitchmark locates instants of glottal closure in a laryngograph waveform, and performs post-processing to produce even pitchmarks. EST does not currently provide any means of pitchmarking a speech waveform.

Pitchmarking is performed by calling the pitchmark() function, which carries out the following operations:

1. Double low pass filter the signal. This removes noise in the signal. The parameter lx_lf specifies the low pass cutoff frequency, and lx_lo specifies the order. Double filtering (feeding the waveform through the filter, then reversing the waveform and feeding it through again) is performed to reduce any phase shift between the input and output of the filtering operation.
2. Double high pass filter the signal. This removes the very low frequency swell that is often observed in laryngograph waveforms. The parameter lx_hf specifies the high pass cutoff frequency, and lx_ho specifies the order. Double filtering is performed to reduce any phase shift between the input and output of the filtering operation.
3. Calculate the delta signal. The filtered waveform is differentiated using the delta() function.
4. Low pass filter the delta signal. Some noise may still be present in the signal, and this is removed by further low pass filtering. Experimentation has shown that simple mean smoothing is often more effective than FIR smoothing at this point. The parameter mo is used to specify the size of the mean smoothing window. If FIR smoothing is chosen, the parameter df_lf specifies the low pass cutoff frequency, and df_lo specifies the order. Double filtering is again used to avoid phase distortion.
5. Pick zero crossings. Now simple zero-crossing is used to find the pitchmarks themselves.

pitchmark also performs post-processing on the pitchmarks. This can be used to eliminate pitchmarks which occur too closely together, or to provide estimated evenly spaced pitchmarks during unvoiced regions. The -fill option switches this facility on, and -min, -max, -def, -end and -wave_end control its operation.

Options

Examples

Basic Pitchmarking**:

$ pitchmark kdt_010.lar -o kdt_010.pm -otype est

Pitchmarking with unvoiced regions filled**: The following fills unvoiced regions with pitch periods that are about 0.01 seconds long. It also post-processes the set of pitchmarks and ensures that noe are above 0.02 seconds long and none below 0.003. A final unvoiced region extending to the end of the wave is specified by using the -wave_end option.

$ pitchmark kdt_010.lar -o kdt_010.pm -otype est -fill -min 0.003  \
   -max 0.02 -def 0.01 -wave_end