>> ssig=Pascalize(sig,60);scales a signal sig such that its sound pressure level is 60 dB.
Make_GTbank is an interactive function which can be used to design various types of gammatone filterbanks. This is called by
The function asks first user to specify the type of the filterbank. There are three alternatives: (1) conventional gammatone implementation is the one introduced by Malcolm Slaney . The second and third alternatives are a (2) fourth-order and a (3) sixth-order complex-valued gammatone filterbank for which HUTear has an efficient implementation which uses cgtbank.mex** function. Derivation of these filters can be found Here.
Next, the user is asked to give sampling rate in Hertz. After that, the function gives three alternatives: (1) specify all center frequencies in Hertz, (2) specify all center frequencies in ERB (1-42), and (3) give the number of channels and the lowest center frequency.
After that, the user is asked if he/she wants to store the coefficients directly to a file or to just take the coefficient matrices to Matlab's workspace. AudMod assumes that the coefficients are row vectors in matrices which named f and b as above.
>> [a,b]=Make_OEM(44100,255,'ELC','FIR'); >> save filename.mat a bdesigns a 255th order FIR approximation at 44100 Hz sampling rate which is matched with the Equal Loudness Curves at the loudness level of 0 phon. The coefficients are stored here in a mat-file (filename.mat). It is important that the coefficient vectors are named a and b. Otherwise, AudMod is not able to identify the filter coefficients.
It is possible to design also IIR filters using the same function, see help Make_OEM. In addition, if WarpTB is available, it is also possible to design and use frequency-warped FIR and IIR filters.
There is an interactive graphical user interface for Make_OEM in the toolbox. It is called by
>> OEMtoolIt can be used to compare different implementation technique as a function of model order and finally to store the coefficients to a named file.