<s>
Speech	B-Application
enhancement	I-Application
aims	O
to	O
improve	O
speech	O
quality	O
by	O
using	O
various	O
algorithms	O
.	O
</s>
<s>
The	O
objective	O
of	O
enhancement	O
is	O
improvement	O
in	O
intelligibility	O
and/or	O
overall	O
perceptual	O
quality	O
of	O
degraded	O
speech	O
signal	O
using	O
audio	B-Algorithm
signal	I-Algorithm
processing	I-Algorithm
techniques	O
.	O
</s>
<s>
Enhancing	O
of	O
speech	O
degraded	O
by	O
noise	O
,	O
or	O
noise	O
reduction	O
,	O
is	O
the	O
most	O
important	O
field	O
of	O
speech	B-Application
enhancement	I-Application
,	O
and	O
used	O
for	O
many	O
applications	O
such	O
as	O
mobile	O
phones	O
,	O
VoIP	B-Application
,	O
teleconferencing	O
systems	O
,	O
speech	B-Application
recognition	I-Application
,	O
speaker	B-Application
diarization	I-Application
,	O
and	O
hearing	O
aids	O
.	O
</s>
<s>
The	O
algorithms	O
of	O
speech	B-Application
enhancement	I-Application
for	O
noise	O
reduction	O
can	O
be	O
categorized	O
into	O
three	O
fundamental	O
classes	O
:	O
filtering	O
techniques	O
,	O
spectral	O
restoration	O
,	O
and	O
model-based	O
methods	O
.	O
</s>
