Voice activated password implementation in python

Question

I want to record a word beforehand and when the same password is spoken into the python script, the program should run if the spoken password matches the previously recorded file. I do not want to use the speech recognition toolkits as the passwords might not be any proper word but could be complete gibberish. I started with saving the previously recorded file and the newly spoken sound as numpy arrays. Now I need a way to determine if the two arrays are 'close' to each other. Can someone point me in the right direction for this?

Answer 1

It is not possible to compare to speech samples on a sample level (or time domain). Each part of the spoken words might vary in length, so they won't match up, and the levels of each part will also vary, and so on. Another problem is that the phase of the individual components that the sound signal consists of can change too, so that two signals that sound the same can look very different in the time domain. So likely the best solution is to move the signal into the frequency domain. One common way to do this is using the Fast Fourier Transform (FFT). You can look it up, there is a lot of material about this on the net, and good support for it in Python.

Then could could proceed like this:

• Divide the sound sample into small segments of a few milliseconds.

• Find the principal coefficients of FFT of segments.

• Compare the sequences of some selected principal coefficients.