.. note::
    :class: sphx-glr-download-link-note

    Click :ref:`here <sphx_glr_download_auto_examples_plot_3_1_2_spectrum.py>` to download the full example code
.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_plot_3_1_2_spectrum.py:


==================================
Energy Spectrum of an Audio Signal
==================================

Figure 3.3 from the tutorial.



.. image:: /auto_examples/images/sphx_glr_plot_3_1_2_spectrum_001.png
    :class: sphx-glr-single-img





.. code-block:: default


    from os.path import dirname, abspath, join
    from scipy.io import loadmat
    import numpy as np
    import matplotlib.pyplot as plt

    DATA_PATH = join(abspath(dirname("__file__")), "data", "gabor.mat")
    signal = loadmat(DATA_PATH)['gabor'].ravel()
    time = np.arange(338)
    dsp = np.fft.fftshift(np.abs(np.fft.fft(signal)) ** 2)
    freq = np.arange(-169, 169, dtype=float) / 338 * 1000

    plt.subplot(211)
    plt.plot(time, signal)
    plt.grid(True)
    plt.xlim(0, time.max())
    plt.xlabel('Time (ms)')

    plt.subplot(212)
    plt.plot(dsp)
    plt.grid(True)
    plt.title('Spectrum')
    plt.xlabel('Frequency (Hz)')

    plt.subplots_adjust(hspace=0.5)

    plt.show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** ( 0 minutes  0.227 seconds)


.. _sphx_glr_download_auto_examples_plot_3_1_2_spectrum.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example



  .. container:: sphx-glr-download

     :download:`Download Python source code: plot_3_1_2_spectrum.py <plot_3_1_2_spectrum.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: plot_3_1_2_spectrum.ipynb <plot_3_1_2_spectrum.ipynb>`


.. only:: html

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

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