Example: linear_gammachirp (hears)

Example of the use of the class LinearGammachirp available in the library. It implements a filterbank of FIR gammatone filters with linear frequency sweeps as described in Wagner et al. 2009, “Auditory responses in the barn owl’s nucleus laminaris to clicks: impulse response and signal analysis of neurophonic potential”, J. Neurophysiol. In this example, a white noise is filtered by a gammachirp filterbank and the resulting cochleogram is plotted. The different impulse responses are also plotted.

from brian import *
from brian.hears import *

sound = whitenoise(100*ms).ramp()
sound.level = 50*dB

nbr_center_frequencies = 10  #number of frequency channels in the filterbank
#center frequencies with a spacing following an ERB scale
center_frequencies = erbspace(100*Hz, 1000*Hz, nbr_center_frequencies)

c = 0.0 #glide slope
time_constant = linspace(3, 0.3, nbr_center_frequencies)*ms

gamma_chirp = LinearGammachirp(sound, center_frequencies, time_constant, c)

gamma_chirp_mon = gamma_chirp.process()

figure()

imshow(gamma_chirp_mon.T, aspect='auto')
figure()
plot(gamma_chirp.impulse_response.T)
show()