<s>
A	O
long-range	O
acoustic	O
device	O
(	O
LRAD	O
)	O
,	O
acoustic	B-Device
hailing	I-Device
device	I-Device
(	O
AHD	O
)	O
or	O
sound	O
cannon	O
is	O
a	O
specialized	O
loudspeaker	O
that	O
produces	O
sound	O
at	O
high	O
power	O
for	O
communicating	O
at	O
a	O
distance	O
.	O
</s>
<s>
Other	O
uses	O
have	O
included	O
for	O
negotiations	O
in	O
siege	B-Application
situations	O
to	O
deal	O
with	O
piracy	O
at	O
sea	O
;	O
for	O
mass	O
notification	O
during	O
natural	O
disasters	O
or	O
other	O
emergencies	O
;	O
and	O
by	O
defense	O
forces	O
,	O
including	O
several	O
navies	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
are	O
acoustic	O
devices	O
capable	O
of	O
outputting	O
highly	O
intelligible	O
sound	O
at	O
very	O
high	O
volumes	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
can	O
come	O
in	O
two	O
forms	O
;	O
</s>
<s>
Omnidirectional	O
models	O
:	O
These	O
acoustic	B-Device
hailing	I-Device
devices	I-Device
are	O
capable	O
of	O
creating	O
360°	O
voice	O
communications	O
and	O
warning	O
tones	O
.	O
</s>
<s>
The	O
term	O
acoustic	B-Device
hailing	I-Device
device	I-Device
came	O
into	O
common	O
use	O
following	O
the	O
suicide	O
attack	O
on	O
the	O
while	O
it	O
was	O
at	O
port	O
in	O
Yemen	O
in	O
2000	O
.	O
</s>
<s>
Following	O
this	O
attack	O
,	O
the	O
United	O
States	O
Navy	O
established	O
a	O
requirement	O
for	O
an	O
acoustic	B-Device
hailing	I-Device
device	I-Device
.	O
</s>
<s>
Since	O
their	O
inception	O
with	O
the	O
introduction	O
of	O
the	O
Long	O
Range	O
Acoustic	O
Device	O
(	O
LRAD	O
)	O
in	O
2002	O
,	O
acoustic	B-Device
hailing	I-Device
devices	I-Device
have	O
grown	O
into	O
a	O
variety	O
of	O
applications	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
are	O
now	O
fielded	O
all	O
over	O
the	O
world	O
by	O
various	O
commercial	O
,	O
law	O
enforcement	O
,	O
and	O
military	O
groups	O
.	O
</s>
<s>
Following	O
this	O
attack	O
,	O
navies	O
around	O
the	O
world	O
made	O
several	O
policy	O
changes	O
,	O
while	O
the	O
American	O
Technology	O
Corporation	O
(	O
which	O
was	O
rebranded	O
to	O
LRAD	O
Corporation	O
in	O
2010	O
and	O
to	O
Genasys	O
in	O
late	O
October	O
2019	O
)	O
created	O
and	O
developed	O
the	O
AHD	O
market	O
,	O
which	O
included	O
the	O
launch	O
of	O
its	O
proprietary	O
Long	O
Range	O
Acoustic	O
Device	O
,	O
a	O
type	O
of	O
acoustic	B-Device
hailing	I-Device
device	I-Device
,	O
in	O
2003	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
differ	O
from	O
conventional	O
speaker	O
systems	O
in	O
three	O
key	O
ways	O
:	O
volume	O
,	O
clarity	O
,	O
and	O
directionality	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
have	O
an	O
output	O
of	O
135	O
decibels	O
(	O
dB	O
)	O
or	O
greater	O
.	O
</s>
<s>
SPL	O
is	O
a	O
logarithmic	O
measure	O
of	O
the	O
rms	B-General_Concept
sound	O
pressure	O
of	O
a	O
sound	O
relative	O
to	O
a	O
reference	O
value	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
sound	O
emitted	O
from	O
acoustic	B-Device
hailing	I-Device
devices	I-Device
is	O
intelligible	O
at	O
distance	O
.	O
</s>
<s>
LRAD	O
products	O
range	O
from	O
hand-held	O
devices	O
to	O
those	O
mounted	O
on	O
helicopters	B-Application
,	O
motor	O
vehicles	O
and	O
ships	O
.	O
</s>
<s>
Large	O
speakers	O
(	O
or	O
large	O
arrays	O
)	O
,	O
such	O
as	O
these	O
,	O
have	O
an	O
interference	O
pattern	O
in	O
the	O
nearfield	B-Algorithm
which	O
produces	O
peaks	O
6dB	O
higher	O
than	O
the	O
output	O
pressure	O
and	O
nulls	O
where	O
the	O
pressure	O
is	O
essentially	O
zero	O
.	O
</s>
<s>
The	O
larger	O
the	O
speaker	O
,	O
and	O
the	O
higher	O
the	O
frequency	O
,	O
the	O
longer	O
the	O
effective	O
nearfield	B-Algorithm
.	O
</s>
<s>
The	O
nearfield	B-Algorithm
for	O
this	O
device	O
is	O
approximately	O
.	O
</s>
<s>
Acoustic	B-Device
hailing	I-Device
devices	I-Device
have	O
the	O
potential	O
to	O
be	O
used	O
as	O
non-lethal	O
weapons	O
.	O
</s>
<s>
However	O
,	O
before	O
2020	O
,	O
there	O
was	O
no	O
use	O
of	O
the	O
LRAD	O
in	O
public	O
situations	O
;	O
most	O
usage	O
had	O
been	O
by	O
the	O
various	O
police	O
forces	O
for	O
communications	O
during	O
natural	O
disasters	O
or	O
for	O
negotiations	O
with	O
hostage-takers	O
in	O
a	O
siege	B-Application
,	O
where	O
it	O
was	O
too	O
dangerous	O
to	O
approach	O
a	O
suspect	O
.	O
</s>
<s>
The	O
Japanese	O
fleet	O
later	O
escalated	O
the	O
use	O
of	O
LRAD	O
,	O
deploying	O
it	O
against	O
a	O
Sea	O
Shepherd	O
helicopter	B-Application
carrying	O
a	O
camera	O
crew	O
.	O
</s>
<s>
Sea	O
Shepherd	O
noted	O
that	O
they	O
had	O
an	O
LRAD	O
of	O
their	O
own	O
,	O
but	O
as	O
of	O
early	O
2010	O
,	O
had	O
not	O
put	O
it	O
into	O
use	O
other	O
than	O
to	O
play	O
a	O
recording	O
of	O
"	O
Ride	O
of	O
the	O
Valkyries	O
"	O
in	O
the	O
manner	O
of	O
attacking	O
U.S.	O
Army	O
helicopters	B-Application
depicted	O
in	O
the	O
1979	O
film	O
Apocalypse	O
Now	O
.	O
</s>
<s>
Genasys	O
has	O
supplied	O
its	O
NEWS	O
mass	O
notification	O
service	O
in	O
Australia	O
since	O
2013	O
,	O
when	O
it	O
partnered	O
with	O
Nokia	O
to	O
deliver	O
emergency	O
notifications	O
via	O
SMS	B-Device
,	O
following	O
the	O
disastrous	O
consequences	O
of	O
the	O
Black	O
Saturday	O
bushfires	O
in	O
2009	O
.	O
</s>
<s>
On	O
November	O
5	O
,	O
2005	O
,	O
the	O
luxury	O
cruise	O
ship	O
Seabourn	O
Spirit	O
employed	O
an	O
LRAD	O
to	O
repel	O
pirates	B-Application
who	O
attacked	O
the	O
vessel	O
with	O
rocket-propelled	O
grenades	O
about	O
115km	O
off	O
the	O
coast	O
of	O
Somalia	O
.	O
</s>
<s>
The	O
effectiveness	O
of	O
this	O
device	O
during	O
the	O
attack	O
is	O
not	O
completely	O
clear	O
,	O
but	O
the	O
pirates	B-Application
did	O
not	O
succeed	O
in	O
boarding	O
the	O
vessel	O
and	O
eventually	O
fled	O
.	O
</s>
<s>
Following	O
a	O
one-sided	O
shootout	O
,	O
the	O
ship	O
was	O
seized	O
and	O
the	O
unarmed	O
security	O
contractors	O
abandoned	O
ship	O
leaving	O
the	O
ship	O
and	O
crew	O
to	O
the	O
pirates	B-Application
.	O
</s>
<s>
In	O
January	O
2011	O
,	O
the	O
Spirit	O
of	O
Adventure	O
,	O
a	O
cruise	O
ship	O
sailing	O
through	O
the	O
Indian	O
Ocean	O
,	O
deployed	O
an	O
LRAD	O
system	O
as	O
part	O
of	O
its	O
defensive	O
measures	O
when	O
being	O
pursued	O
by	O
pirates	B-Application
.	O
</s>
<s>
S/Y	O
Hideaway	O
used	O
an	O
LRAD	O
in	O
2016	O
to	O
deter	O
suspected	O
pirates	B-Application
in	O
the	O
Gulf	O
of	O
Aden	O
.	O
</s>
