The present study measured the head-related transfer functions (HRTFs) of the Mongolian gerbil for various sound-source directions, and explored acoustical cues for sound localization that could be available to the animals. The HRTF exhibited spectral notches for frequencies above 25 kHz. The notch frequency varied systematically with source direction, and thereby characterized the source directions well. The frequency dependence of the acoustical axis, the direction for which the HRTF amplitude was maximal, was relatively irregular and inconsistent between ears and animals. The frequency-by-frequency plot of the interaural level difference (ILD) exhibited positive and negative peaks, with maximum values of 30 dB at around 30 kHz. The ILD peak frequency had a relatively irregular spatial distribution, implying a poor sound localization cue. The binaural acoustical axis (the direction with the maximum ILD magnitude) showed relatively orderly clustering around certain frequencies, the pattern being fairly consistent among animals. The interaural time differences (ITDs) were also measured and fell in a ±120μs range. When two different animal postures were compared (i.e., the animal was standing on its hind legs and prone), small but consistent differences were found for the lower rear directions on the HRTF amplitudes, the ILDs, and the ITDs.

1.
Ågren
,
G.
,
Zhou
,
Q.
, and
Zhong
,
W.
(
1989
). “
Ecology and social behavior of Mongolian gerbils, Meriones unguiculatus, at Xilinhot, Inner Mongolia, China
,”
Anim. Behav.
37
,
11
27
.
2.
Behrend
,
O.
,
Brand
,
A.
,
Kapfer
,
C.
, and
Grothe
,
B.
(
2002
). “
Auditory response properties in the superior paraolivary nucleus of the gerbil
,”
J. Neurophysiol.
87
,
2915
2928
.
3.
Brand
,
A.
,
Behrend
,
O.
,
Marquardt
.
T.
,
McAlpine
,
D.
, and
Grothe
,
B.
(
2002
). “
Precise inhibition is essential for microsecond interaural time difference coding
,”
Nature (London)
417
,
543
547
.
4.
Brückner
,
S.
, and
Rübsamen
,
R.
(
1995
). “
Binaural response characteristics in isofrequency sheets of the gerbil inferior colliculus
,”
Hear. Res.
86
,
1
14
.
5.
Carlile
,
S.
, and
Pettigrew
,
A. G.
(
1987
). “
Directional properties of the auditory periphery in the guinea pig
,”
Hear. Res.
31
,
111
122
.
6.
Carlile
,
S.
(
1990
). “
The auditory periphery of the ferret. I: Directional response properties and the pattern of interaural level differences
,”
J. Acoust. Soc. Am.
88
,
2180
2195
.
7.
Chan
,
J. C.
, and
Geisler
,
C. D.
(
1990
). “
Estimation of eardrum acoustical pressure and of ear canal length from remote points in the canal
,”
J. Acoust. Soc. Am.
87
,
1237
1247
.
8.
Coles
,
R. B.
, and
Guppy
,
A.
(
1986
). “
Biophysical aspects of directional hearing in the Tammar wallaby, Macropus Eugenii
,”
J. Exp. Biol.
121
,
371
394
.
9.
Ellard
,
C. G.
,
Goodale
,
M. A.
, and
Timney
,
B.
(
1984
). “
Distance estimation in the Mongolian gerbil: The role of dynamic depth cues
,”
Behav. Brain Res.
14
,
29
39
.
10.
Firzlaff
,
U.
, and
Schuller
.
G.
(
2003
). “
Spectral directionality of the external ear of the lesser spear-nosed bat, Phyllostomus discolor
,”
Hear. Res.
181
,
27
39
.
11.
Fuzessery
,
Z. M.
(
1996
), “
Monaural and binaural spectral cues created by the external ears of the pallid bat
,”
Hear. Res.
95
,
1
17
.
12.
Grothe
,
B.
(
2003
). “
New roles for synaptic inhibition in sound localization
,”
Nat. Rev. Neurosci.
4
,
540
550
.
13.
Hammershøi
,
D.
, and
Møller
,
H.
(
1996
). “
Sound transmission to and within the human ear canal
,”
J. Acoust. Soc. Am.
100
,
408
427
.
14.
Hârper
N. S.
, and
McAlpine
,
D.
(
2004
). “
Optimal neural population coding of an auditory spatial cue
,”
Nature (London)
430
,
682
686
.
15.
Heffner
,
R. S.
, and
Heffner
,
H. E.
(
1988
). “
Sound localization and use of binaural cues by the gerbil (Meriones unguiculatus)
,”
Behav. Neurosci.
102
,
422
428
.
16.
Irvine
,
D. R.
(
1987
). “
Interaural intensity differences in the cat: Changes in sound pressure level at the two ears associated with azimuthal displacements in the frontal horizontal plane
,”
Hear. Res.
26
,
267
286
.
17.
Jen
,
P. H.
, and
Chen
,
D. M.
(
1988
). “
Directionality of sound pressure transformation at the pinna of echolocating bats
,”
Hear. Res.
34
,
101
117
.
18.
Keller
,
C. H.
,
Hartung
,
K.
, and
Takahashi
,
T. T.
(
1998
). “
Head-related transfer functions of the barn owl: Measurement and neural responses
,”
Hear. Res.
118
,
13
34
.
19.
Kelly
,
J. B.
, and
Potas
,
M.
(
1986
). “
Directional responses to sounds in young gerbils (Meriones unguiculatus)
,”
J. Comp. Psychol.
100
,
37
45
.
20.
Knudsen
,
E. I.
, and
Konishi
,
M
(
1979
). “
Mechanisms of sound localization in the barn owl (Tyto alba)
,”
J. Comp. Physiol.
133
,
13
21
.
21.
Kuhn
,
G. F.
(
1977
). “
Model for the interaural time differences in the azimuthal plane
,”
J. Acoust. Soc. Am.
62
,
157
167
.
22.
Maki
,
K.
, and
Furukawa
,
S.
(
2003
). “
Acoustical cues for sound localization by gerbils in an ecologically realistic environment
,”
Assoc. Res. Otolaryngol. Abs.
26
,
89
.
23.
McAlpine
,
D.
, and
Grothe
,
B.
(
2003
). “
Sound localization and delay lines—do mammals fit the model?
,”
Trends Neurosci.
26
,
347
350
.
24.
Mehrgardt
,
S.
, and
Mellert
,
V.
(
1977
). “
Transformation characteristics of the external human ear
,”
J. Acoust. Soc. Am.
61
,
1567
1576
.
25.
Middlebrooks
J. C.
, and
Pettigrew
,
J. D.
(
1981
). “
Functional classes of neurons in primary auditory cortex of the cat distinguished by sensitivity to sound location
,”
J. Neurosci.
1
,
107
120
.
26.
Middlebrooks
,
J. C.
,
Makous
,
J. C.
, and
Green
,
D. M.
(
1989
). “
Directional sensitivity of sound-pressure levels in the human ear canal
,”
J. Acoust. Soc. Am.
86
,
89
108
.
27.
Middlebrooks
,
J. C.
, and
Green
,
D. M.
(
1990
). “
Directional dependence of interaural envelope delays
,”
J. Acoust. Soc. Am.
87
,
2149
2162
.
28.
Middlebrooks
,
J. C.
, and
Green
,
D. M.
(
1991
). “
Sound localization by human listeners
,”
Annu. Rev. Psychol.
42
,
135
159
.
29.
Moiseff
,
A.
(
1989
). “
Binaural disparity cues available to the barn owl for sound localization
,”
J. Acoust. Soc. Am.
59
,
1222
1226
.
30.
Musicant
,
A. D.
,
Chan
,
J. C.
, and
Hind
,
J. E.
(
1990
). “
Direction-dependent spectral properties of cat external ear: New data and cross-species comparisons
,”
J. Acoust. Soc. Am.
87
,
757
781
.
31.
Obrist
,
M. K.
,
Fenton
,
M. B.
,
Eger
,
J. L.
, and
Schlegel
,
P. A.
(
1993
). “
What ears do for bats: A comparative study of pinna sound pressure transformation in chiroptera
,”
J. Exp. Biol.
180
,
119
152
.
32.
Parsons
,
J. E.
, and
Lim
,
E.
, and
Voigt
,
H. F.
(
2001
). “
Type III units in the gerbil dorsal cochlear nucleus may be spectral notch detectors
,”
Ann. Biomed. Eng.
29
,
887
896
.
33.
Phillips
,
D. P.
,
Calford
,
M. B.
,
Pettigrew
,
J. D.
,
Aitkin
,
L. M.
, and
Semple
,
M. N.
(
1982
). “
Directionality of sound pressure transformation at the cat’s pinna
,”
Hear. Res.
8
,
13
28
.
34.
Ravicz
,
M. E.
,
Rosowski
,
J. J.
, and
Voigt
,
H. F.
(
1996
). “
Sound-power collection by the auditory periphery of the Mongolian gerbil Meriones unguiculatus. II. External-ear radiation impedance and power collection
,”
J. Acoust. Soc. Am.
99
,
3044
3063
.
35.
Rice
,
J. J.
,
May
,
B. J.
,
Spirou
,
G. A.
, and
Young
,
E. D.
(
1992
). “
Pinna-based spectral cues for sound localization in cat
,”
Hear. Res.
58
,
132
152
.
36.
Roth
,
G. L.
,
Kochhar
,
R. K.
, and
Hind
,
J. E.
(
1980
). “
Interaural time differences: Implications regarding the neurophysiology of sound localization
,”
J. Acoust. Soc. Am.
68
,
1643
1651
.
37.
Ryan
,
A.
(
1976
). “
Hearing sensitivity of the mongolian gerbil, Meriones unguiculatus
,”
J. Acoust. Soc. Am.
59
,
1222
1226
.
38.
Sanes
,
D. H.
(
1990
). “
An in vitro analysis of sound localization mechanisms in the gerbil lateral superior olive
,”
J. Neurosci.
110
,
3494
3506
.
39.
Searle
,
C. L.
,
Braida
,
L. D.
,
Cuddy
,
D. R.
, and
Davis
,
M. F.
(
1975
). “
Binaural pinna disparity: Another auditory localization cue
,”
J. Acoust. Soc. Am.
57
,
448
455
.
40.
Shaw
,
E. A.G.
(
1982
). “
External ear response and sound localization
,” in
Localization of Sound: Theory and Applications
(
Amphora
, Groton, CT), pp.
30
41
.
41.
Spezio
,
M. L.
,
Keller
,
C. H.
,
Marrocco
,
R. T.
, and
Takahashi
,
T. T.
(
2000
). “
Head-related transfer functions of the rhesus monkey
,”
Hear. Res.
144
,
73
88
.
42.
Spitzer
,
M. W.
, and
Semple
,
M. N.
(
1995
). “
Neurons sensitive to interaural phase disparity in gerbil superior olive: Diverse monaural and temporal response properties
,”
J. Neurophysiol.
73
,
1668
1690
.
43.
Suzuki
,
Y.
,
Asano
,
F.
,
Kim
,
H.-Y.
, and
Sone
,
T.
(
1995
). “
An optimum computer-generated pulse signal suitable for the measurement of very long impulse responses
,”
J. Acoust. Soc. Am.
97
,
1119
1123
.
44.
Woodworth
,
R. S.
, and
Schlosberg
,
H.
(
1962
).
Experimental Psychology
(
Holt
, Rinehard and Winston, New York), pp.
349
361
.
45.
Wotton
,
J. M.
,
Haresign
,
T.
, and
Simmons
,
J. A.
(
1995
). “
Spatially dependent acoustical cues generated by the external ear of the big brown bat, Eptesicus fuscus
,”
J. Acoust. Soc. Am.
98
,
1423
1445
.
46.
Young
,
E. D.
,
Rice
,
J. J.
, and
Tong
,
S. C.
(
1996
). “
Effects of pinna position on head-related transfer functions in the cat
,”
J. Acoust. Soc. Am.
99
,
3064
3076
.
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