# What is the x and y axis showing for this matplotlib.pyplot histogram of a .wav file?

The python code below generates a histogram from a .wav file, but what exactly does the histogram show? Is the x axis amplitude binned by sampling rate? Is the y axis a count of how many samples are in each amplitude bin? And how is amplitude calculated?

import numpy as np
import matplotlib.pyplot as plt

plt.hist(data, bins='auto')
plt.show()


It seems we have a confusion with the meaning of the term frequency in different contexts.
The histogram plots frequencies in the statistic sense. Each bin corresponds to an event defined as "the sample has value in the interval $$b_k < x_i < b_{k+1}$$", where $$b_k$$ corresponds to the position of the vertical edges of each bar in your histogram.