1.1 Speech Signal Processing

The tree major engineering applications of speech signal processing:

Block diagram of digital speech transmission:

The speech is transformed by an encoder into a sequence of bits,transmitted over a channel, and then converted back into an audible signal.
Speech is often coded as parameters that represent the signal economically while still allowing speech reconstruction at the receiver with minimal loss.
The terms coding and coder include both the analysis and the synthesis stages of speech processing:

"whatever is done by the encoder must be undone by decoder, to reproduce the output speech".

1.1 Speech coding

1.2 1 Historical Perspective

- in Bell Telephone Laboratories, in the late thirties (Homer Dudley)

- motivation:

to develop systems for transmission of speech over low - bandwith telegraph cables

- first analysis - synthesis method

1.2.2 What is Speech Coding?

"Speech Coding" = finding a representation of speech which can be transmitted efficiently through a digital channel.


1.2.3 Why speech Coding at all?

- need for compression of bit rate


1.2.4 Applications