Full text of DOI:10.1080/00016480117952

Acta Oto-Laryngologica
ISSN: 0001-6489 (Print) 1651-2251 (Online) Journal homepage: http://www.tandfonline.com/loi/ioto20
Binaural Interaction of Bone-conducted Auditory
Brainstem Responses
Mitsutoshi Setou, Takahide Kurauchi, Toshihiro Tsuzuku & Kimitaka Kaga
To cite this article: Mitsutoshi Setou, Takahide Kurauchi, Toshihiro Tsuzuku & Kimitaka Kaga
(2001) Binaural Interaction of Bone-conducted Auditory Brainstem Responses, Acta Oto-
Laryngologica, 121:4, 486-489, DOI: 10.1080/00016480117952
To link to this article: http://dx.doi.org/10.1080/00016480117952
Published online: 08 Jul 2009.
Submit your article to this journal
Article views: 6
View related articles
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=ioto20
Download by: [University of Lethbridge]
Date: 07 May 2016, At: 13:25

Acta Otolaryngol 2001; 121: 486–489
Binaural Interaction of Bone-conducted Auditory Brainstem Responses
1
1
2
MITSUTOSHI SETOU , TAKAHIDE KURAUCHI , TOSHIHIRO TSUZUKU and
1
KIMITAKA KAGA
1
2
From the Departments of Otolaryngology, Faculty of Medicine, Uni×ersity of Tokyo and Departments of Otolaryngology, Teikyo
Uni×ersity, Tokyo, Japan.
Setou M, Kurauchi T, Tsuzuku T, Kaga K. Binaural interaction of bone-conducted auditory brainstem responses. Acta
Otolaryngol 2001; 121: 486–489.
Bone-conducted auditory brainstem responses (ABRs) elicited by monoaural stimulation are very useful for evaluating
hearing in children with congenital atresia of both ears. In a previous study of sound lateralization in children with
congenital atresia of both ears, using bilateral bone-conducted stimuli, we found that most of the children could
sufŽ ciently retain binaural hearing ability in terms of both intensity and time differences. In this study we attempted to
record bilateral bone-conducted ABRs in normal subjects in order to explore binaural interaction objectively. The study
revealed that binaural interaction exists in bone-conducted ABRs. This can be taken as neurophysiological evidence that
sound lateralization can be detected by children with bilateral microtia and atresia. Key words: microtia, atresia, auditory
brainstem responses, binaural interaction, bone conduction.
MATERIALS AND METHODS
INTRODUCTION
Seven adults (25–30 years of age) with normal hear-
ing were examined. All tests were carried out in a
sound-proofed and shielded room. Subjects were al-
lowed to fall asleep naturally.
Bilateral aural atresia frequently accompanies bilat-
eral microtia in children. These children are Ž tted
with bone-conducted hearing aids (BHA) to improve
their hearing ability. Our previous study (1) revealed
that Ž tting of BHAs to each mastoid tip enabled
children to detect sound lateralization, as determined
using the automatic sound lateralization test for 500
Hz band noise. As this test was subjectively acoustic,
we wanted to obtain more objective data based on
the phenomenon of ‘binaural interaction’ (BI)
recorded using auditory brainstem responses (ABRs).
BI in air-conducted ABRs was recognized in a previ-
ous experiment (2). The BI wave appears just before
the wave IV–V complex. Waves IV and V are
thought to be generated mainly in the lateral lemnis-
cus and inferior colliculus (3, 4). BI is suspected to be
the electrical activity of the brainstem auditory path-
way from the superior olive. Diminution of the BI
following trapezoid body surgical section was demon-
strated (5). These anatomical areas are also suspected
of being the generators of binaural hearing. There-
fore, many researchers have suspected that BI of
ABRs should re ect the neural activity of processing
binaural hearing (2–6).
Clicks were generated by passing 0.1-ms square
pulses using a Neuropak 8 NEB 4208 (Nihon Ko-
hden) pulse generator through an attenuator to a pair
of matched bone-conducted vibrators on the bilateral
mastoid tips at 45 dB HL greater than the threshold
hearing level of each subject. The stimulus presenta-
tion rate was 10 Hz.
5
Electrical activity from the scalp was ampliŽ ed 10
times and Ž ltered between 100 and 2000 Hz. Elec-
trodes were placed along the midline of the scalp with
the active electrode placed at the vertex (Cz), refer-
ence electrodes on each mastoid (M1 far right and far
left M2) and a common (ground) electrode placed on
the upper forehead (Fpz). Interelectrode impedance
was B2 kV.
All the subjects were tested under each of three
conditions: binaural, right monaural and left monau-
ral presentation of stimulus. Two repeatable averages
were recorded for each condition. Bilateral external
auditory canals were completely plugged with silicon
rubber.
In general, children with bilateral aural atresia
have mostly conductive or partially mixed hearing
loss because of an occluded external auditory canal
and a middle-ear anomaly. However, in patients with
conductive hearing loss, it is possible to detect the
gaps between air- and bone-conducted thresholds of
ABRs. Based on these facts, we designed a study to
record the BI of bone-conducted ABRs in subjects
with normal hearing whose ears were plugged
bilaterally.
BI was determined by subtracting the sum of the
monaural auditory-evoked potentials from the binau-
ral-evoked potential, as given by the following for-
mula (Fig. 1):
BI¾binaural¼(left monaural»right monaural)
Individually averaged peak latencies and trough-to-
peak amplitude values were obtained. An ANOVA,
within-subjects design was used to determine BI. All
statistical comparisons in this study were considered
signiŽ cant at the p¾0.01 level.
©
2001 Taylor & Francis. ISSN 0001-6489

Acta Otolaryngol 121
Binaural interaction of bone-conducted ABRs
487
Typical recordings of the BI of the bone-conducted
ABRs in four subjects are shown in Fig. 2. BI was
calculated to show a large negative wave at approxi-
mately the peak latency of waves IV–V of the
monaural ABRs. The amplitude of the binaural ABR
was statistically signiŽ cantly lower than the sum of
the amplitudes of the right and left monaural ABRs.
The amplitude and latency of the right and left
monaural ABRs were not signiŽ cantly different
RESULTS
(
Table I, Fig. 3). The latencies of the binaural and
monaural V waves showed no signiŽ cant differences
Table IIFig. 4). The calculated BI wave is a negative
(
wave with one sharp trough near the wave V peak.
The onset time of the BI is close to that of wave IV.
The BI latency is signiŽ cantly different from that of
wave V.
DISCUSSION
Fig. 1. Measurement of latency and amplitude of ABR and
BI. Wave IV–V complex of ABR: the period from the start
of recording to the rising point of the wave IV–V complex
was determined as the onset latency. Peak latency was
measured from the start of recording to the peak of this
wave. The distance between the rising point of the wave
IV–V complex and the peak of this wave was determined
as the amplitude of the wave IV–V complex. BI: the period
from the start of recording to the descending point of BI
was determined as the onset latency. Peak latency was
measured from the start of recording to the peak of this
wave. The distance between the descending point of the BI
complex and the bottom of this wave was determined as the
amplitude of BI.
It has been reported that monoaural bone-conducted
ABRs, as well as air-conducted ABRs have been
clearly recorded (7–9). The BI wave was also
recorded in bone-conducted ABRs (bone BI wave) as
well as in air-conducted ABRs (air BI wave). The BI
occurred at a latency close to that of the IV and V
waves. The bone BI wave was a sharp negative wave
with 1 peak, similar to the shape of the air BI wave
for 40 dB stimulation. There is a general consensus
that the acoustic stapedial re ex has little or no effect
on ABR differences for monaural vs binaural click
stimulation at the 40 dB level.
Bone BI peak latency was signiŽ cantly different
from the wave V latency. The bone BI wave appeared
just before the IV–V wave and the air BI wave. BI of
air-conducted ABRs has been reported in both ani-
mals and humans by many researchers (2–6, 10–12).
However, the generator of the bone BI wave is un-
known. Wada and Starr (5), in experiments on guinea
pigs, observed loss of the BI in component P4 follow-
ing trapezoid body surgical section, indicating that
crossing Ž bers in the trapezoid body are essential for
the occurrence of the electrophysiological sign of
binaural processing. It is possible that the generator
of the bone BI wave is the same as that of the air BI
wave.
For this experiment we chose 40 dB stimulation,
which was almost the lowest level necessary to evoke
clear BI. There is a higher probability of cross-hear-
ing at a higher level. The crossover effect is an
important problem (13). Using a broad-band mask-
ing noise does not overcome the problem of stimulus
crossover during binaural stimulation. The masking
noise was not presented in this study. Thus, the
bone-conducted method cannot eliminate cross-hear-
Fig. 2. Typical recordings of BI of bone-conducted ABRs
in four subjects. In each case the upper trace shows the
recording of bilateral stimulation, the middle two traces
represent the recordings of monaural stimulation of each
ear and the lower trace shows the BI wave. BI was clearly
recorded with bone-conducted stimulation. Note that the
onset of BI occurred later than that of the IV–V wave
complex.

488
M. Setou et al.
Acta Otolaryngol 121
Table I. Amplitudes of wa×e VI–V complex and BI (mV)
Subject
Right Ear
Left ear
Bilateral
Sum of right»left
BI
1
2
3
4
5
6
7
1.90
1.05
1.10
2.25
1.70
2.40
1.60
1.90
1.35
0.95
2.10
2.05
2.25
1.70
2.25
2.40
1.10
2.30
2.15
3.10
2.65
3.80
2.40
2.05
4.35
3.75
4.65
3.30
2.50
0.95
1.90
1.80
3.35
3.40
2.55
Mean
SD
1.71
0.52
1.76
0.46
2.28
0.61
3.47
0.96
2.35
0.88
Fig. 4. Mean9SD of onset and peak latencies of the wave
IV–V complex and BI. There is a signiŽ cant difference in
onset latency between the wave IV–V complex and BI.
There is a signiŽ cant difference in the peak latencies be-
tween the wave IV–V complex and BI.
Fig. 3. Mean amplitudes9SD of wave V and BI. There is
a signiŽ cant difference in the mean amplitude between the
right monoaural-, left monoaural-, bilateral- and BI-evoked
responses. However, there is no signiŽ cant difference in
amplitude between the right monoaural-, left monoaural-,
bilateral- and BI-evoked responses.
lower at the stimulated-side mastoid than at any
other part of the skull, but that thresholds at low
frequencies at the stimulated-side mastoid were the
same as those at the opposite side of the stimulated
mastoid. These Ž ndings suggest that bone conduction
sound lateralization may be present because of the
differences between the right and left mastoid con-
ductions. In our experiment, the stimulus used was a
high-frequency click for the stimulated-side mastoid.
In conclusion, the BI is a useful neurophysiological
measure of bilaterally stimulated bone- and air-con-
ducted ABRs.
ing (14). In our previous subjective study we did not
present the masking noise either. Thus, cross-hearing
may be not an obstacle but a cue to binaural hearing.
Kirikae (15) demonstrated that the thresholds of
bone conduction vibration at high frequencies were
Table II. Onset and peak latency of wa×e IV–V complex and BI (ms)
Right ear
Onset
Left ear
Onset
Bilateral
Onset
BI
Subject
Peak
Peak
Peak
Onset
Peak
1
2
3
4
5
6
7
5.10
5.68
5.84
5.12
5.35
6.00
4.80
6.80
7.23
7.45
6.80
6.62
7.11
6.42
5.12
5.44
5.60
5.36
5.38
5.16
5.48
6.91
7.04
7.77
6.82
6.71
6.67
6.65
5.12
5.40
5.80
5.44
5.36
5.28
5.10
6.62
6.97
7.15
6.73
6.62
6.57
6.26
6.13
6.95
7.00
6.29
6.14
6.10
5.91
7.12
7.36
7.78
7.23
7.17
7.68
6.82
Mean
SD
5.41
0.44
6.92
0.36
5.36
0.17
6.94
0.39
5.36
0.23
6.70
0.29
6.36
0.43
7.31
0.33

Acta Otolaryngol 121
Binaural interaction of bone-conducted ABRs
489
Laryngol 1989; 98: 941–9.
. Kaga K, Tanaka Y: Auditory air and bone con-
ACKNOWLEDGMENTS
9
duction brainstem responses and damped rotation test
for young children with bilateral congenital atresia
of the ears. Int J Pediat Otorhinolaryngol 32: 13–21,
The authors express their gratitude to M. Amorim (Coll e` ge
de France, CNRS LPPA Paris) for assistance with statisti-
cal design and analysis and Ms. H Miyazaki for typing the
manuscript.
1
995.
0. Dobie RA, Berlin CI. Binaural interaction in brain-
stem-evoked responses. Arch Otolaryngol 1979; 105:
91 –8.
1. Levine RA. Binaural interaction in brainstem poten-
tials of human subjects. Ann Neruol 1981; 9: 394–408.
1
3
REFERENCES
1
1
. Kaga K, Setou M, Nakamura M. Bone-conducted
sound lateralization of interaural time difference and
interaural intensity difference in children and a young
adult with bilateral microtia and atresia of the ears.
Acta Otolaryngol 2001; 121: 274–7.
1
2. McPherson DL, Tures C, Starr A. Binaural interaction
of the auditory brain-stem potentials and middle la-
tency auditory evoked potentials in infants and adults.
Electroencephalogr Clin Neurophysiol 1989; 74: 124–
30.
2
3
. Jewett DJ. Volume conducted potentials in response
to auditory stimuli as detected by averaging in the
cat. Electroenceph Clin Neurophysiol 1970; 2l8:
1
3. Suzuki T, Kobayashi K, Aoki K, et al. Effect of sleep
on binaural interaction in auditory brainstem response
and middle latency response. Audiology 1992; 31: 25–
609–18.
30.
. Buchwald JS. Generators. Bases of auditory brain-stem
evoked responses. In: Moore EJ, ed. Grune & Stratton.
Bases of Auditory Brain-stem Evoked Responses. 1983:
1
4. Dirks DD. Bone-conduction threshold testing. In: Katz
J, ed. Handbook of clinical audiology, 4th edn .
Williams & Wilkins. Baltimore, Philadelphia. 132–46
5. Kirikae I. An experimental study on the fundamental
mechanism of bone conduction, Acta Otolaryngol
Suppl 1959; 145: 1–111.
1
57–195.
1
4
5
. Wrege KS, Starr A. Binaural interaction in human
auditory brainstem evoked potentials. Arch Neurol
1981; 38: 572–80.
. Wada S-I, Starr A. Generation of auditory brain stem
responses (ABRs). II. Effects of surgical section of
the trapezoid body on the ABR in guinea pigs and
cat. Electroenceph Clin Neurophysiol 1983; 56:
Address for correspondence:
K. Kaga
3
40–51.
Department of Otolaryngology
Faculty of Medicine
University of Tokyo
7-3-1 Hongo, Bunkyo-ku
Tokyo
6
7
8
. Fowler CG, Leonards JS. Frequency dependence of the
binaural interaction component of the auditory brain-
stem response. Audiology 1985; 24: 420–9.
. Mauldin L, Jerger J. Auditory brain stem evoked re-
sponse to bone-conducted signals. Arch Otolaryngol
Japan
1979; 105: 656–61.
Fax: »81 3 3814 9486
Tel: »81 3 5800 8665
E-mail: kimikaga-tky@umin.ac.jp
. Stapells DR, Ruben RJ. Auditory brain stem responses
to bone conducted tones in infants. Ann Otol Rhinol
.