Find large number of consecutive values fulfilling condition in a numpy array

Question

I have some audio data loaded in a numpy array and I wish to segment the data by finding silent parts, i.e. parts where the audio amplitude is below a certain threshold over

Answer 1

Slightly sloppy, but simple and fast-ish, if you don't mind using scipy:

from scipy.ndimage import gaussian_filter
sigma = 3
threshold = 1
above_threshold = gaussian_filter(data, sigma=sigma) > threshold

The idea is that quiet portions of the data will smooth down to low amplitude, and loud regions won't. Tune 'sigma' to affect how long a 'quiet' region must be; tune 'threshold' to affect how quiet it must be. This slows down for large sigma, at which point using FFT-based smoothing might be faster.

This has the added benefit that single 'hot pixels' won't disrupt your silence-finding, so you're a little less sensitive to certain types of noise.