<s>
Query	B-Application
by	I-Application
humming	I-Application
(	O
QbH	O
)	O
is	O
a	O
music	B-Application
retrieval	I-Application
system	O
that	O
branches	O
off	O
the	O
original	O
classification	O
systems	O
of	O
title	O
,	O
artist	O
,	O
composer	O
,	O
and	O
genre	O
.	O
</s>
<s>
The	O
system	O
involves	O
taking	O
a	O
user-hummed	O
melody	O
(	O
input	O
query	B-Library
)	O
and	O
comparing	B-Application
it	I-Application
to	O
an	O
existing	O
database	O
.	O
</s>
<s>
The	O
system	O
then	O
returns	O
a	O
ranked	O
list	O
of	O
music	O
closest	O
to	O
the	O
input	O
query	B-Library
.	O
</s>
<s>
One	O
example	O
of	O
this	O
would	O
be	O
a	O
system	O
involving	O
a	O
portable	O
media	O
player	O
with	O
a	O
built-in	O
microphone	B-Application
that	O
allows	O
for	O
faster	O
searching	B-Application
through	O
media	O
files	O
.	O
</s>
<s>
Examples	O
of	O
QbH	O
systems	O
include	O
ACRCloud	O
,	O
SoundHound	B-Application
,	O
Musipedia	O
,	O
and	O
Tunebot	B-Application
.	O
</s>
