STFT of an Audio Signal

Figure 3.4 from the tutorial.

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()
tfr = loadmat(DATA_PATH)['tfr']
time = np.arange(338)
freq = np.arange(128, dtype=float) / 256.0 * 1000

plt.contour(time, freq, tfr)
plt.grid(True)
plt.xlabel('Time  [ms]')
plt.ylabel('Frequency  [Hz]')
plt.title('Squared modulus of the STFT of the word GABOR')
plt.show()