.. _sphx_glr_auto_examples_Elements_plot_frequency_scale.py:


================
Frequency Scale
================

Illustration of the different frequency scales




.. code-block:: python


    from simplecochlea.utils import utils_cochlea
    import matplotlib.pyplot as plt
    import seaborn as sns
    sns.set()
    sns.set_context('paper')








Suppose we want a cochlea whose frequency domain range from 20 Hz to 20000 Hz with 100 hair cells
Each hair cell can be modeled as a band-pass filter. Each one selecting a certain frequency range.
An important parameter is the way these band-pass filters are organized and cover the whole frequency range
of hearing.



.. code-block:: python

    fmin, fmax = 20, 20000
    n_filters = 100
    fs = 44100







A unrealistic but simple way to organize the band-pass filters is to use a *linear scale*.
The :func:`utils_cochlea.linearscale` returns both the filters cutoff and center frequencies



.. code-block:: python

    wn_lin, cf_lin = utils_cochlea.linearscale(fs, fmin, fmax, n_filters)







A more realistic solution to model the tonotopy of the cochlea is to use the ERB scale (Equivalent Rectangular
Bandwitdh) :



.. code-block:: python

    wn_erb, cf_erb = utils_cochlea.erbscale(fs, fmin, fmax, n_filters)







Let's plot the evolution of the center frequencies for both scales :



.. code-block:: python

    f = plt.figure()
    ax = f.add_subplot(111)
    ax.stem(cf_lin, markerfmt='C0o')
    ax.stem(cf_erb, markerfmt='C1o')
    ax.set(xlabel='Filter Number', ylabel='Frequency', title='Evolution of the Center Frequency of Bandpass filters')
    ax.legend(['Linear Scale', 'ERB Scale'])





.. image:: /auto_examples/Elements/images/sphx_glr_plot_frequency_scale_001.png
    :align: center




**Total running time of the script:** ( 0 minutes  3.047 seconds)



.. only :: html

 .. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: plot_frequency_scale.py <plot_frequency_scale.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: plot_frequency_scale.ipynb <plot_frequency_scale.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_