Broadcasting arrays

In a nutshell, NumPy tries to perform an operation even though the operands do not have the same shape. In this section, we will multiply an array and a scalar. The scalar is extended to the shape of an array operand, and then the multiplication is performed. We will download an audio file and make a new version that is quieter:

1. First, read the WAV file. We will use standard Python code to download an audio file of Austin Powers saying "Smashing, baby". SciPy has a wavfile module that allows you to load sound data or generate WAV files. If SciPy is installed, then we should already have this module. The read() function returns a data array and sample rate. In this example, we only care about the data.

   sample_rate, data = scipy.io.wavfile.read(WAV_FILE)

2. Plot the original WAV data with Matplotlib. Give the subplot the title, Original, as shown in the following lines of code:

   plt.subplot(2, 1, 1)
   plt.title("Original")
   plt.plot(data)

3. Now create a new array. We will use NumPy to...