*Variables*
and their meanings are:

**srate**
The sampling rate of the output waveform (Hz). NB This should
not be changed from the default of 20kHz without changing the Digital filters.

**frate**
The frame rate (Hz). The number of frames of input per second. Default 100 Hz.

**cratef**
The Glottal function sampling rate. Default 5000 Hz.

**cratex**
Excitation sub-frame rate (Normally a tenth of
**srate**
). Default 2000 Hz.

**fqlow, fqstep**
Values for calculating the frequencies at which entries in the cosine table for formant generators are calculated. F = fqlow + n * fqstep, n = 0..255.

**bwlow, bwstep **
The exponent table used in the formant generator is calculated using frequencies F = bwlow + n * bwstep, n = 0..31.

**foscal, fobase**
Values for calculating the excitation pitch table. Excitation frequencies are
F = foscal * ( fobase ** ( n/16)), n = 0..63. These correspond with the control values 0..254.

**dbstep**
Separation in decibels of amplitude controls. ie value I 0..63 gives an amplitude of 10**( (I-63) * dbstep / 20). Default value 1 dB.

**aoffdn, foffdn, scaldn**
Used to calculate the degree of nasality for any given ALF, A1 and F1 control values. aoffdn is in decibels, foffdn in Hertz, scaldn is a scale factor. These are combined to give the degree of nasality in the following formula.
Dnasal = ( max (0, ALF-A1-aoffdn) * max (0, F1-foffdn) ) / scaldn

**conts**
contant component of glottal pulse length.

**grpl**
Glottal pulse length gradient. pulse length = conts + grpl / ms. Where ms is the mark/space ratio.

**xscale **
Scale factor for excitation both voiced and unvoiced to give output range.

**foi**
Fundamental frequency of a typical single impulse excitation. Used to scale power of unvoiced excitation.

**gclf**
Gain control for the low frequency formant. Such that if F1 is 500Hz its gain will be equal to the higher formants.

**sil**
In a single impulse excitation a period of noise is replaced by a single impulse of equivalent power. This is the length of that period in milliseconds.

**gouv**
Glottal area for unvoiced conditions.

**isqthr**
Frequency maintanance threshold accross frames (in control values).

**lsqthr**
As isqthr for silent formants.

**ictlof**
Integer control offsets. Used to modify control values individually.

**flflim->fmgain**
These are all formant parameters in the order F1, F2, F3, FHF, FHFUV, FN.

**flflim**
Formant low frequency limits in Hz.

**fincrm**
Formant frequency steps in Hz.

**bdwtab**
Formant fixed bandwidths in Hz.

**bdwmod**
Formant bandwidth modifications in Hz.

**bdwnas**
As bdwmod but for nasals.

**fqmod**
Formant frequency modifications.

**dvoffs**
Offsets for voiced /unvoiced mixing for each formant.

**fmgain**
Individual gain for each formant.

**ifrecl->ipocl **
Clamping limits, if exceded formant clamping occurs. All are measured in control parameter steps.

**ifrecl**
Limit of frequency change.

**iampcl**
Limit of amplitude change.

**ipocl**
Fundamental period limit.

**alfcon**
If set to -1 F1 is removed from FN, if 0 it has no effect.

**expat**
List of integers specifying the glottal pulse shape. Values in the range -127 to +127.

**gapat**
list of integers specifying the glottal area. Values in the range 0 to 15 where 15 means fully open.