.. currentmodule:: brian

.. index::
   pair: example usage; erbspace
   pair: example usage; tone
   pair: example usage; Gammatone
   pair: example usage; sqrt
   pair: example usage; whitenoise

.. _example-hears_online_computation:

Example: online_computation (hears)
===================================

Example of online computation using :meth:`~brian.hears.Filterbank.process`.
Plots the RMS value of each channel output by a gammatone filterbank.

::

    from brian import *
    from brian.hears import *
    
    sound1 = tone(1*kHz, .1*second)
    sound2 = whitenoise(.1*second)
    
    sound = sound1+sound2
    sound = sound.ramp()
    
    sound.level = 60*dB
    
    cf = erbspace(20*Hz, 20*kHz, 3000)
    fb = Gammatone(sound, cf)
    
    def sum_of_squares(input, running):
        return running+sum(input**2, axis=0)
    
    rms = sqrt(fb.process(sum_of_squares)/sound.nsamples)
    
    sound_rms = sqrt(mean(sound**2))
    
    axhline(sound_rms, ls='--')
    plot(cf, rms)
    xlabel('Frequency (Hz)')
    ylabel('RMS')
    show()