The air/water interface at the top of a body of water is often treated from below as a pressure release boundary, which it closely matches. The small discrepancy in that match, however, is enough to enable humans in air to hear sounds generated underwater, which would not be possible across a pressure release boundary. A discussion of this phenomenon, designed for teaching purposes and using no more acoustics than would be contained in a first-year undergraduate syllabus in acoustics, leads to a discussion of whether goldfish can hear their owners speaking. The analysis is then used to illustrate the care needed when comparing sound levels in air and water, a process which continues to lead to erroneous statements in the media and some academic articles.

1.
O. A.
Godin
,
“Sound transmission through water–air interfaces: New insights into an old problem,”
Contemp. Phys.
49
,
105
123
(
2008
).
2.
National Marine Fisheries Service, Office of Protected Resources, “Assessment of acoustic exposures on marine mammals in conjunction with USS Shoup active sonar transmissions in the Eastern Strait of Juan de Fuca and Haro Strait, Washington, 5 May 2003” (January 21, 2005).
3.
O. A.
Godin
, “
Anomalous transparency of water-air interface for low-frequency sound
,”
Phys. Rev. Lett.
97
,
164301
(
2006
).
4.
O. A.
Godin
, “
Transmission of low-frequency sound through the water-to-air interface
,”
Acoust. Phys.
53
,
305
312
(
2007
).
5.
O. A.
Godin
, “
Low-frequency sound transmission through a gas–liquid interface
,”
J. Acoust. Soc. Am.
123
,
1866
1879
(
2008
).
6.
B. E.
McDonald
and
D. C.
Calvo
, “
Enhanced sound transmission from water to air at low frequencies
,”
J. Acoust. Soc. Am.
122
,
3159
3161
(
2007
).
7.
T. G.
Leighton
,
D. C.
Finfer
,
G. H.
Chua
,
P. R.
White
, and
J. K.
Dix
, “
Clutter suppression and classification using twin inverted pulse sonar in ship wakes
,”
J. Acoust. Soc. Am.
130(5)
,
3431
3437
(
2011
).
8.
I. N.
Didenkulov
and
A. M.
Sutin
,
“The influence of the subsurface bubble layer on wind ambient noise generation,”
in
Natural Physical Sources of Underwater Sound
, edited by
B. R.
Kerman
(
Kluwer
,
Dordrecht, The Netherlands
,
1992
).
9.
A. A.
Hudimac
, “
Ray theory solution for the sound intensity in water due to a point source above it
,”
J. Acoust. Soc. Am.
29
,
916
917
(
1957
).
10.
M.
Weinstein
and
A.
Henney
, “
Wave solution for air-to-water sound transmission
,”
J. Acoust. Soc. Am.
37
,
899
901
(
1965
).
11.
H.
Medwin
and
J. D.
Hagy
, “
Helmholtz-Kirchhoff theory for sound transmission through a statistically rough plane interface between dissimilar fluids
,”
J. Acoust. Soc. Am.
51
,
1083
1090
(
1972
).
12.
R. J.
Urick
, “
Noise signature of an aircraft in level flight over a hydrophone in thesea
,”
J. Acoust. Soc. Am.
52
,
993
999
(
1972
).
13.
R.
Young
, “
Sound pressure in water from a source in air and vice versa
,”
J. Acoust. Soc. Am.
53
,
1708
1716
(
1973
).
14.
D.
Bordelon
, “
Sound pressure in air from a source in water and vice versa
,”
J. Acoust. Soc. Am.
55
,
869
870
(
1974
).
15.
T. G.
Leighton
,
The Acoustic Bubble
(
Academic Press
,
London
,
1994
), pp.
22
25
,194, Fig. 3.23.
16.
L. M.
Brekhovskikh
and
Yu. P.
Lysanov
,
Fundamentals of Ocean Acoustics, Springer Series on Wave Phenomenon
, 2nd ed., edited by
L. B.
Felsen
(
Springer-Verlag
,
Berlin
,
1990
), pp. 66,
76
83
.
17.
M. E.
Smith
,
A. S.
Kane
, and
A. N.
Popper
,
“Acoustical stress and hearing sensitivity in fishes: Does the linear threshold shift hypothesis hold water?”
J. Exp. Biol.
207
,
3591
3602
(
2004
).
18.
M. E.
Smith
,
A. S.
Kane
, and
A. N.
Popper
, “
Noise-induced stress response and hearing loss in goldfish (Carassius auratus)
,”
J. Exp. Biol.
207
,
427
435
(
2004
).
19.
P. H.
Dahl
,
J. H.
Miller
,
D. H.
Cato
, and
R. K.
Andrew
, “
Underwater ambient noise
,”
Acoust. Today
1
,
23
33
(
2007
).
20.
D. C.
Finfer
,
T. G.
Leighton
, and
P. R.
White
, “
Issues relating to the use of a 61.5 dB conversion factor when comparing airborne and underwater anthropogenic noise levels
,”
Appl. Acoust.
69(5)
,
464
471
(
2008
).
21.
D. H.
Cato
,
“The effects of noise on marine animals in the context of their natural acoustic environment,”
in
Proceedings of 20th International Congress on Acoustics
, I.C.A. 2010,
Sydney, Australia
(August 23–27,
2010
).
22.
The New York Times editorial, “Sonar Over Whales,” November 15, 2008, http://www.nytimes.com/2008/11/15/opinion/15sat3.html (Last viewed 19 September 2011), p. A20.
23.
BBC Nature News, “‘Singing penis’ sets noise record for water insect,” June 30, 2011, http://www.bbc.co.uk/nature/13958630 (Last viewed 19 September 2011).
24.
The Daily Mail, “The grunt stops here: Tennis officials plan crackdown on noisy players,” June 14, 2009, http://www.dailymail.co.uk/news/article-1192948/The-grunt-stops-Tennis-officials-plan-crackdown-noisy-players.html (Last viewed 19 September 2011).
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