Long description
This is a screenshot from Interactive 5, showing the recording of the word ‘yes’ with noise added from Figure 33. A notch filter has been applied to the signal, indicated by the grey shading of a small vertical section around the 1.221 kilohertz line in the frequency domain.
Below the original two graphs are the time and frequency representations of the filtered signal. In both time and frequency domains, the signal looks almost identical to the original signal in Figure 32.