Selected subjects with bilateral cochlear implants (CIs) showed excellent horizontal localization of wide-band sounds in previous studies. The current study investigated localization cues used by two bilateral CI subjects with outstanding localization ability. The first experiment studied localization for sounds of different spectral and temporal composition in the free field. Localization of wide-band noise was unaffected by envelope pulsation, suggesting that envelope-interaural time difference (ITD) cues contributed little. Low-pass noise was not localizable for one subject and localization depended on the cutoff frequency for the other which suggests that ITDs played only a limited role. High-pass noise with slow envelope changes could be localized, in line with contribution of interaural level differences (ILDs). In experiment 2, processors of one subject were raised above the head to void the head shadow. If they were spaced at ear distance, ITDs allowed discrimination of left from right for a pulsed wide-band noise. Good localization was observed with a head-sized cardboard inserted between processors, showing the reliance on ILDs. Experiment 3 investigated localization in virtual space with manipulated ILDs and ITDs. Localization shifted predominantly for offsets in ILDs, even for pulsed high-pass noise. This confirms that envelope ITDs contributed little and that localization with bilateral CIs was dominated by ILDs.

1.
Blauert
,
J.
(
1997
).
Spatial Hearing
(
MIT Press
, Cambridge, MA).
2.
Buell
,
T. N.
, and
Hafter
,
E. R.
(
1991
). “
Combination of binaural information across frequency bands
,”
J. Acoust. Soc. Am.
90
,
1894
1900
.
3.
Firszt
,
J. B.
,
Holden
,
L. K.
,
Skinner
,
M. W.
,
Tobey
,
E. A.
,
Peterson
,
A.
,
Gaggl
,
W.
,
Ruge-Samuelson
,
C. L.
, and
Wackym
,
P. A.
(
2004
). “
Recognition of speech presented at soft to loud levels by adult cochlear implant recipients of three cochlear implant systems
,”
Ear Hear.
25
,
375
387
.
4.
Freyman
,
R. L.
, and
Zurek
,
P. M.
(
1997
). “
Onset dominance in lateralization
,”
J. Acoust. Soc. Am.
101
,
1649
1659
.
5.
Grantham
,
D. W.
,
Ashmead
,
D. H.
, and
Ricketts
,
T. A.
(
2005
). “
Sound localization in the frontal horizontal plane by post-lingually deafened adults fitted with bilateral cochlear implants
,” in
Auditory Signal Processing: Physiology, Psychoacoustics, and Models
, edited by
D.
Pressnitzer
,
A. d.
Cheveigne
,
S.
McAdams
, and
L.
Collet
,
Springer-Verlag
,
New York
, pp.
390
397
.
6.
Hafter
,
E.
(
1996
). “
Binaural adaptation and the effectiveness of a stimulus beyond its onset
,” in
Binaural and Spatial Hearing in Real and Virtual Environments
, edited by
R. H.
Gilkey
and
T. R.
Anderson
(
Lawrence Erlbaum
, Mahwah, NJ), pp.
211
232
.
7.
Hafter
,
E. R.
, and
Jeffress
,
L. A.
(
1968
). “
Two-image lateralization of tones and clicks
,”
J. Acoust. Soc. Am.
44
,
563
569
.
8.
Hartmann
,
W. A.
(
1996
). “
Listening in a room and the precedence effect
,” in
Binaural and Spatial Hearing in Real and Virtual Environments
, edited by
R. H.
Gilkey
and
T. R.
Anderson
(
Lawrence Erlbaum
, Mahwah, NJ), pp.
191
210
.
9.
Hartmann
,
W. M.
,
Rakerd
,
B.
, and
Koller
,
A.
(
2005
). “
Binaural coherence in rooms
,”
Acta. Acust. Acust.
91
,
451
462
.
10.
Henning
,
G. B.
(
1974
). “
Detectability of interaural delay in high-frequency complex waveforms
,”
J. Acoust. Soc. Am.
55
,
84
90
.
11.
Klumpp
,
R. G.
, and
Eady
,
H. R.
(
1956
). “
Some measurements of interaural time difference thresholds
,”
J. Acoust. Soc. Am.
28
,
859
860
.
12.
Laback
,
B.
,
Pok
,
S. M.
,
Baumgartner
,
W. D.
,
Deutsch
,
W. A.
, and
Schmid
,
K.
(
2004
). “
Sensitivity to interaural level and envelope time differences of two bilateral cochlear implant listeners using clinical sound processors
,”
Ear Hear.
25
,
488
500
.
13.
Laszig
,
R.
,
Aschendorff
,
A.
,
Stecker
,
M.
,
Mueller-Deile
,
J.
,
Maune
,
S.
,
Dillier
,
N.
,
Weber
,
B.
,
Hey
,
M.
,
Begall
,
K.
,
Lenarz
,
T.
,
Battmer
,
R.-D.
,
Boehm
,
M.
,
Steffens
,
T.
,
Strutz
,
J.
,
Linder
,
T.
,
Probst
,
R.
,
Allum
,
J.
,
Westhofen
,
M.
, and
Doering
,
W.
(
2004
). “
Benefits of bilateral electrical stimulation with the nucleus cochlear implant in adults: 6-month postoperative results
,”
Otol. Neurotol.
25
,
958
968
.
14.
Lawson
,
D. T.
,
Brill
,
S.
,
Wolford
,
R. D.
,
Wilson
,
B. S.
, and
Schatzer
,
R.
(
2000
). “
Speech processors for auditory prostheses
,” in Ninth Quarterly Progress Report (Research Triangle Park:
Research Triangle Institute
).
15.
Lawson
,
D. T.
,
Wilson
,
B. S.
,
Zerbi
,
M.
,
Honert
,
C. v.-d.
,
Finley
,
C. C.
,
Farmer
,
J. C.
,
McElveen
,
J. T.
, and
Roush
,
P. A.
(
1998
). “
Bilateral cochlear implants controlled by a single speech processor
,”
Am. J. Otol.
19
,
758
761
.
16.
Lawson
,
D. T.
,
Wolford
,
R. D.
,
Brill
,
S.
,
Schatzer
,
R.
, and
Wilson
,
B. S.
(
2001
). “
Speech processors for auditory prostheses
,” in Twelfth Quarterly Progress Report (Research Triangle Park:
Research Triangle Institute
).
17.
Long
,
C. J.
,
Eddington
,
D. K.
,
Colburn
,
H. S.
, and
Rabinowitz
,
W. M.
(
2003
). “
Binaural sensitivity as a function of interaural electrode position with a bilateral cochlear implant user
,”
J. Acoust. Soc. Am.
114
,
1565
1574
.
18.
Macpherson
,
E. A.
, and
Middlebrooks
,
J. C.
(
2002
). “
Listener weighting of cues for lateral angle: The duplex theory of sound revisited
,”
J. Acoust. Soc. Am.
111
,
2219
2236
.
19.
Majdak
,
P.
,
Laback
,
B.
, and
Baumgartner
,
W. D.
(
2006
). “
Effects of interaural time differences in fine structure and envelope on lateral discrimination in electric hearing
,”
J. Acoust. Soc. Am.
120
,
2190
2201
.
20.
Mills
,
A. W.
(
1958
). “
On the minimum audible angle
,”
J. Acoust. Soc. Am.
30
,
237
246
.
21.
Nopp
,
P.
,
Schleich
,
P.
, and
D’Haese
,
P.
(
2004
). “
Sound localization in bilateral users of MED-EL COMBI 4040+ cochlear implants
,”
Ear Hear.
25
,
205
214
.
22.
Qin
,
M. K.
, and
Oxenham
,
A. J.
(
2003
). “
Effects of simulated cochlear-implant processing on speech reception in fluctuating maskers
,”
J. Acoust. Soc. Am.
114
,
446
454
.
23.
Schoen
,
F.
,
Mueller
,
J.
,
Helms
,
J.
, and
Nopp
,
P.
(
2005
). “
Sound localization and sensitivity to interaural cues in bilateral users of the Med-El Combi 4040+cochlear implant system
,”
Otol. Neurotol.
26
,
429
437
.
25.
Seeber
,
B.
(
2002
). “
A new method for localization studies
,”
Acta. Acust. Acust.
88
,
446
450
.
26.
Seeber
,
B.
,
Baumann
,
U.
, and
Fastl
,
H.
(
2004
). “
Localization ability with bimodal hearing aids and bilateral cochlear implants
,”
J. Acoust. Soc. Am.
116
,
1698
1709
.
27.
Shaw
,
E. A. G.
(
1974
). “
Transformation of sound pressure level from the free field to the eardrum in the horizontal plane
,”
J. Acoust. Soc. Am.
56
,
1848
1861
.
28.
Smith
,
Z. M.
,
Delgutte
,
B.
, and
Oxenham
,
A. J.
(
2002
). “
Chimaeric sounds reveal dichotomies in auditory perception
,”
Nature (London)
416
,
87
90
.
29.
Strutt
,
J. W. L. R.
(
1907
). “
On our perception of sound direction
,”
Philos. Mag.
13
,
214
232
.
30.
Tyler
,
R. S.
,
Gantz
,
B. J.
,
Rubinstein
,
J. T.
,
Wilson
,
B. S.
,
Parkinson
,
A. J.
,
Wolaver
,
A. W.
,
Preece
,
J. P.
,
Witt
,
S.
, and
Lowder
,
M. W.
(
2002
). “
Three-month results with bilateral cochlear implants
,”
Ear Hear.
23
,
80S
89S
.
31.
van de Par
,
S.
, and
Kohlrausch
,
A.
(
1997
). “
A new approach to comparing binaural masking level differences at low and high frequencies
,”
J. Acoust. Soc. Am.
101
,
1671
1680
.
32.
van Hoesel
,
R.
,
Ramsden
,
R.
, and
O’Drisoll
,
M.
(
2002
). “
Sound-direction identification, interaural time delay discrimination, and speech intelligibility advantages in noise for a bilateral cochlear implant user
,”
Ear Hear.
23
,
137
149
.
33.
van Hoesel
,
R. J.
(
2007
). “
Sensitivity to binaural timing in bilateral cochlear implant users
,”
J. Acoust. Soc. Am.
121
,
2192
2206
.
34.
van Hoesel
,
R. J. M.
(
2004
). “
Exploring the benefits of bilateral cochlear implants
,”
Audiol. Neuro-Otol.
9
,
234
246
.
35.
van Hoesel
,
R. J. M.
, and
Clark
,
G. M.
(
1997
). “
Psychophysical studies with two binaural cochlear implant subjects
,”
J. Acoust. Soc. Am.
102
,
495
507
.
36.
van Hoesel
,
R. J. M.
,
Tong
,
Y. C.
,
Hollow
,
R. D.
, and
Clark
,
G. M.
(
1993
). “
Psychophysical and speech perception studies: A case report on a binaural cochlear implant subject
,”
J. Acoust. Soc. Am.
94
,
3178
3189
.
37.
van Hoesel
,
R. J. M.
, and
Tyler
,
R. S.
(
2003
). “
Speech perception, localization, and lateralization with bilateral cochlear implants
,”
J. Acoust. Soc. Am.
113
,
1617
1630
.
38.
Wightman
,
F. L.
, and
Kistler
,
D. J.
(
1992
). “
The dominant role of low-frequency interaural time differences in sound localization
,”
J. Acoust. Soc. Am.
91
,
1648
1661
.
39.
Wightman
,
F. L.
, and
Kistler
,
D. J.
(
1996
). “
Factors affecting the relative salience of sound localization cues
,” in
Binaural and Spatial Hearing in Real and Virtual Environments
, edited by
R. H.
Gilkey
, and
T. R.
Anderson
(
Lawrence Erlbaum
, Mahwah, NJ), pp.
1
23
.
40.
Wightman
,
F. L.
, and
Kistler
,
D. J.
(
1997
). “
Monaural sound localization revisited
,”
J. Acoust. Soc. Am.
101
,
1050
1063
.
41.
Yost
,
W. A.
(
1981
). “
Lateral position of sinusoids presented with interaural intensive and temporal differences
,”
J. Acoust. Soc. Am.
70
,
397
409
.
42.
Zeng
,
F. G.
,
Nie
,
K.
,
Liu
,
S.
,
Stickney
,
G.
,
Del Rio
,
E.
,
Kong
,
Y. Y.
, and
Chen
,
H.
(
2004
). “
On the dichotomy in auditory perception between temporal envelope and fine structure cues
,”
J. Acoust. Soc. Am.
116
,
1351
1354
.
43.
Zierhofer
,
C. M.
,
Hochmair-Desoyer
,
I.
, and
Hochmair
,
E. S.
(
1995
). “
Electronic design of a cochlear implant for multichannel high-rate pulsatile stimulation strategies
,”
IEEE Trans. Rehabil. Eng.
3
,
112
116
.
You do not currently have access to this content.