Library

Brian hears comes with a package of predefined filter classes to be used as basic blocks by the user. All of them are implemented as filterbanks.

First, a series of standard filters widely used in audio processing are available:

Class	Descripition	Example
IIRFilterbank	Bank of low, high, bandpass or bandstop filter of type Chebyshef, Elliptic, etc…	IIR filterbank
Butterworth	Bank of low, high, bandpass or bandstop Butterworth filters	Butterworth filters
LowPass	Bank of lowpass filters of order 1	Cochleagram

Second, the library provides linear auditory filters developed to model the middle ear transfer function and the frequency analysis of the cochlea:

Class	Description	Example
MiddleEar	Linear bandpass filter, based on middle-ear frequency response properties	Spiking output of the Tan&Carney model
Gammatone	Bank of IIR gammatone filters (based on Slaney implementation)	Gammatone filters
ApproximateGammatone	Bank of IIR gammatone filters (based on Hohmann implementation)	Approximate Gammatone filters
LogGammachirp	Bank of IIR gammachirp filters with logarithmic sweep (based on Irino implementation)	Logarithmic Gammachirp filters
LinearGammachirp	Bank of FIR chirp filters with linear sweep and gamma envelope	Linear Gammachirp filters
LinearGaborchirp	Bank of FIR chirp filters with linear sweep and gaussian envelope

Finally, Brian hears comes with a series of complex nonlinear cochlear models developed to model nonlinear effects such as filter bandwith level dependency, two-tones suppression, peak position level dependency, etc.

Class	Description	Example
DRNL	Dual resonance nonlinear filter as described in Lopez-Paveda and Meddis, JASA 2001	Dual resonance nonlinear filter (DRNL)
DCGC	Compressive gammachirp auditory filter as described in Irino and Patterson, JASA 2001	Compressive Gammachirp filter (DCGC)
TanCarney	Auditory phenomenological model as described in Tan and Carney, JASA 2003	Spiking output of the Tan&Carney model
ZhangSynapse	Model of an inner hair cell – auditory nerve synapse (Zhang et al., JASA 2001)	Spiking output of the Tan&Carney model