Im getting unusual background noise (hiss) when using libspeex in my application. How do I fix that?
One of the causes could be scaling of the input speech. Speex expects signals to have a +-32767 (signed short) dynamic range. If the dynamic range of your signals is too small (e.g. +-1.0), you will suffer important quantization noise. A good target is to have a dynamic range around +=8000 which is large enough, but small enough to make sure there’s no clipping when converting back to signed short.
