What's 'Apply Mel-flooring' for?

[lzm0706]

I want to use part of this code to extract filter bank features, but I don't understand what is the function of a part named //Apply Mel-flooring? And it will make the f-bank feature has many zeros.

[dspavankumar]

Mel-flooring ensures that the computed log filterbank energies are non-negative. If 0<x<1, then log(x)<0 cannot be considered as an "energy", so x is floored to 1 so that the energy through the filter is zero. You may want to check the amplitude level of the raw speech signal if it covers most of its range: for e.g. a 16-bit integer speech should have a dynamic range as close to [-32768, 32767] as possible. If not, increase the volume.

[lzm0706]

I see. Thank you！

[janemyleng]

i also want to extract filter bank features, where should i change?