Updating .gitignore.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Inserting a function to perform preemphasis.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>
Conversions hertz to mel and mel to hertz written, such as the filterbanks.

Signed-off-by: Eduardo Tenorio <embatbr@gmail.com>