digital speech processing

1.Introduction

The frequency range of sounds perceived by humans is something
between 30 Hz (hertz, cycles per second) and 20,000 Hz. Above
20K we hear nothing.

The acoustic file need to format in which speech data can be saved.
In recent years the most popular format (most frequently used
format) has been Microsoft WAV format. There are many other
formats( MKV, AVI.MP3). The difference is in how many samples
occur per second, and exactly each sample is represented.
2.Applications of Digital Speech Processing
The first step in most applications of digital speech processing is to
convert the acoustic waveform to a sequence of numbers. Most modern
A-to-D converters operate by sampling at a very high rate, applying a
digital low pass filter with cutoff set to preserve a prescribed bandwidth,
and then reducing the sampling rate to the desired sampling rate, which
can be as low as twice the cutoff frequency of the sharp-cutoff digital
filter. This discrete-time representation is the starting point for most
applications. From this point, other representations are obtained by digital
processing