I want to reduce the features dimension of speech signals. the used signals have different sizes.
how to get the features with fixed dimension after the dimensionality reduction??
Perhaps you mean the amplitude of the waveforms?
Do you want to make loud words softer, and soft words louder?
Do you use a digital sound processing program? A lot of people like Audacity because it is free and has many of the features needed to make it useful.
The effect that might do what you want is called compression. It reduces the louder waveforms. You can set preferences which adjust the levels at which it operates.
I have performed a feature extraction for voice recognition
however the obtained features have different length (because the used signals have different length)
I want to reduced and fixed the length of the obtained features