<s>
In	O
computing	O
,	O
scratch	B-Application
input	I-Application
is	O
an	O
acoustic-based	O
method	O
of	O
Human-Computer	O
Interaction	O
(	O
HCI	O
)	O
that	O
takes	O
advantage	O
of	O
the	O
characteristic	O
sound	O
produced	O
when	O
a	O
finger	O
nail	O
or	O
other	O
object	O
is	O
dragged	O
over	O
a	O
surface	O
,	O
such	O
as	O
a	O
table	O
or	O
wall	O
.	O
</s>
<s>
Scratch	B-Application
input	I-Application
was	O
invented	O
by	O
Mann	O
et	O
al	O
.	O
</s>
<s>
A	O
natural	B-Application
interface	I-Application
for	O
musical	O
expression	O
operating	O
on	O
scratch	B-Application
input	I-Application
principles	O
was	O
first	O
published	O
and	O
presented	O
in	O
June	O
2007	O
.	O
</s>
<s>
Later	O
that	O
year	O
,	O
it	O
was	O
extended	O
to	O
an	O
implementation	O
on	O
a	O
smartphone	O
and	O
also	O
a	O
wearable	B-Operating_System
computer	I-Operating_System
system	O
.	O
</s>
<s>
In	O
2008	O
,	O
the	O
Scratch	B-Application
Input	I-Application
project	O
demonstrated	O
a	O
mobile	O
device	O
input	O
system	O
utilizing	O
scratch	B-Application
input	I-Application
,	O
simultaneously	O
popularizing	O
the	O
term	O
.	O
</s>
<s>
Scratch	B-Application
input	I-Application
is	O
an	O
enabling	O
input	O
technique	O
that	O
is	O
used	O
in	O
multitude	O
of	O
applications	O
.	O
</s>
<s>
Microsoft	O
has	O
expressed	O
interest	O
in	O
Scratch	B-Application
Input	I-Application
.	O
</s>
