Final Published BAHD Paper Powell et al 2015

Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
A Comparative Study of Audiologic Outcomes for Two
Transcutaneous Bone-Anchored Hearing Devices
ÃHarry R. F. Powell, yz§Alison M. Rolfe, and yz§Catherine S. Birman
ÃRoyal National Throat, Nose and Ear Hospital, London, United Kingdom; yDiscipline of Paediatrics and
Child Health, Sydney Medical School, University of Sydney; zSydney Children’s Hospital Network
(Children’s Hospital at Westmead); and §The Sydney Cochlear Implant Centre, Sydney, Australia
Objective: In 1977, Tjellstrom et al. used the concept of
osseointegration and implanted patients with a titanium
screw as part of the first bone-anchored hearing solution.
Despite good hearing outcomes with the percutaneous
device, there has been a drive for the development of
transcutaneous bone conduction systems because of soft
tissue complications, aesthetics, and loss or failure of the
abutment. This study compares audiologic and quality of life
questionnaire outcomes (author-designed questionnaire) for
two transcutaneous bone conduction implants.
Study Design: Cross-sectional cohort study.
Setting: Tertiary referral hospital and national audiology
service.
Patients: Twelve patients, 10 children and two adults. Six
recipients of each device.
Main Outcome Measures: Pure-tone audiometry, aided
thresholds, speech discrimination scores, and quality of life
questionnaire results.
Results: The unaided four-frequency average air conduction
for affected ears was 60.8 dB HL for the Attract group and
57.8 dBHL for the Sophono group; these improved to mean
aided thresholds of 30.6 dB HL and 29.8 dB HL, respect-
ively. Therewas no statistical difference between the speech
discrimination scores for the two devices in quiet at 55 dB
SPL ( p ¼ 0.33) orin noise ( p ¼ 0.87).
Conclusion: Both systems provide audiologic benefit com-
pared with the unaided situation. Comparing small numbers
of patients, there was no significant difference in aided
thresholds or speech discrimination scores between these
two transcutaneous bone-anchored implants. All Attract and
Sophono users reported improvement in quality of life and
would recommend their device to others in a similar
situation. Key Words: BAHA Attract—Bone conduction—
Bone-anchored hearing implant—Clinicaloutcome—Hearing
loss—Sophono—Transcutaneous.
Otol Neurotol 36:1525–1531, 2015.
Rudimentary bone conduction systems were first used
in the 17th century to help those with hearing impairment
(1). Subsequently, bone conduction hearing aids using a
vibrating transducer on a headband or an elastic arch
have been used for hearing rehabilitation. In 1977,
Tjellstrom et al. (2) used the concept of osseointegration
of Branemark and Harders (3) and implanted patients
with a titanium screw as part of the first bone-anchored
hearing solution. In 2005, an international consensus
statement (4) on the bone-anchored hearing aid (BAHA)
system was developed.
There are two main indications for bone-conducting
devices: conductive or mixed hearing loss, unsuitable for
aiding with conventional air-conduction aids, such as
atresia; and unilateral severe to profound sensorineural
hearing loss.
Because of soft tissue complications, aesthetics, and
loss or failure of the abutment with the percutaneous
BAHA system, there has been a drive for improvements.
Using the Nijmegen linear incision technique and the
next-generation implants and abutments, complication
rates have dropped significantly (5). Nonetheless, there
was still demand for the development of transcutaneous
bone conduction systems. The device of Hough et al. (6)
used electromagnetic induction to vibrate a subcu-
taneous implanted skull magnet. However, nonuse
was a problem because of lack of power with the ear
level processor and unwillingness to use the body level
processor (7).
In 2013, Siegert and Kanderske (8) reported the first
series of results for 20 patients with a transcutaneous
bone conduction implant (TBCI) that uses dual magnets
implanted snugly onto the bone with five screws. In 2014,
another TBCI was released, transmitting sound instead
through the same single osseointegrated titanium screw
used in their percutaneous device.
Address correspondence and reprint requests to: Harry R. F. Powell,
FRCS (ORL-HNS), Royal National Throat, Nose and Ear Hospital, 330
Grays Inn Road, London, WC1X 8DA, U.K.; E-mail: drharrypowell@
msn.com
The authors disclose no conflicts of interest.
Supplemental Digital Content is available for this article.
1525
Otology & Neurotology
36:1525–1531 ß 2015, Otology & Neurotology, Inc.

Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Both these devices provide a transcutaneous bone-
anchored solution. The aim of our study was to compare
the audiologic, clinical, and quality of life (QOL) out-
comes of the two devices in adults and children. Our
study is the first to report on this comparison.
MATERIALS AND METHODS
The two devices to be compared were the Sophono Alpha
(Sophono Inc., Boulder, CO, U.S.A.) and the Cochlear BAHA
Attract (Cochlear Bone-Anchored Solutions AB, Mo¨lnlycke,
Sweden), which will hereafter be referred to as Sophono and
Attract, respectively.
The senior author’s series of three Sophono patients and
seven Attract patients implanted between January 2013 and
June 2014 were informed of the study by telephone and invited
to participate by e-mail. To increase the numbers in the
Sophono group, the Australian Hearing Database was searched
for all patients implanted with Sophono devices (an additional
seven) and these patients were contacted in the same way.
Audiometric Testing Included:
Unilateral aided thresholds at 250 Hz, 500 Hz, 1 kHz,
2 kHz, 4 kHz, and 8 kHz. These were measured using
frequency-specific warble tones presented at 0 degrees
azimuth.
Unaided pure-tone audiometry; air conduction (AC) at
250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz and bone
conduction (BC) at 500 Hz, 1 kHz, 2 kHz, and 4 kHz.
The aided thresholds were converted to decibel Hearing
Level (db HL) (9) to allow comparison with unaided AC.
Speech discrimination testing was conducted using Bam-
ford-Kowal-Bench/Australian Version sentences (10) for the
majority of patients. Because of young age/learning difficulties,
three patients were tested using Northwestern University
Children’s Perception of Speech monosyllabic words (11) with
a four-alternative forced-choice picture-pointing response.
Speech material was presented at 0 degrees azimuth in the
following conditions:
Unaided in quiet at 55 dB SPL.
Aided (monaural, even if binaurally implanted) in quiet at
55 dB SPL.
Aided (monaural, even if binaurally implanted) at 65 dB
SPL with 65 dB SPL multitalker babble noise from 180
degrees azimuth (0 dB signal-to-noise ratio [SNR]).
Because of clinical time constraints and to maximize partici-
pants’ concentration, only one presentation level was used in
quiet for unaided and aided conditions. The level of 55 dB SPL
was chosen to minimize ceiling effects in the aided condition,
while not being too challenging, particularly for the younger
participants.
The gain frequency response of each patient’s speech pro-
cessor was left on his or her preferred settings (and therefore not
changed in any case). To ensure consistency in microphone
mode and noise reduction settings across patients, all speech
processors were checked via the manufacturer’s software before
testing, and these settings changed to the following if necessary.
For Attract patients, directionality was set to ‘‘auto,’’ noise
reduction to ‘‘mid,’’ and position compensation to ‘‘on.’’ For
Sophono patients, the input mode was set to ‘‘adaptive dir’’ (for
patients wearing the Alpha 2 processor) and noise reduction to
‘‘6 dB.’’ Only one Sophono patient was wearing the Alpha 1
processor and, in this case, the input mode was set to ‘‘omni’’
because this was the only option for this device and the noise
reduction to ‘‘6 dB.’’ These noise reduction settings were
chosen because they represented the middle setting for both
Attract and Sophono. We recognize that because of differences
in processing strategies in these devices, they may perform
differently from one another on these settings but this was
deemed the most consistent means of comparison.
Otoform AK impression material was used to occlude the
nontest ear in patients with normal, mild, or moderate nontest
ear thresholds. This was done to enable testing of the implanted
side only.
Two questionnaires were considered for use in the study: The
Entific Medical Systems Questionnaire (12) and the Abbrevi-
ated Profile of Hearing Aid Benefit (13). Because of overlap of
questions and no individual tool being entirely fit for the
purpose, a questionnaire (Supplemental Digital Content,
http://links.lww.com/MAO/A324) was designed using a com-
bination of questions from other tools and several new ques-
tions. This new questionnaire as a whole has not been validated.
All patients (or parents) were asked to complete this at attend-
ance for the audiologic testing.
Patients (or parents) were asked if their QOL had been
improved by the TBCI (‘‘yes,’’ ‘‘no,’’ or ‘‘sometimes yes,
sometimes no’’) and if they would recommend the device to
others in a similar situation (‘‘yes’’ or ‘‘no’’). They were also
asked to rate their overall satisfaction with the device on a scale
from 0 (very dissatisfied) to 10 (very satisfied), with 5 being
‘‘no difference with or without the device.’’ There was no direct
question about skin issues; however, patients (or parents) were
asked if there were any problems with the device, the answer to
which was a free text response.
Ethical approval was granted by the Australian Hearing
Human Research Ethics Committee (approval no. AHH-
REC2014–12).
RESULTS
Six Sophono patients and six Attract patients were
assessed. Four Sophono patients and one Attract patient
were excluded because of logistic and geographic diffi-
culties coordinating testing appointments. One Sophono
patient and four Attract patients had bilateral devices.
There were 10 children and two adults. Table 1 shows the
demographics of the two groups of patients, as well as the
key clinical and questionnaire results.
Mean unaided AC, BC, and mean unilateral aided
thresholds for both devices are shown in Figure 1. The
unaided AC and BC thresholds were comparable for
the two groups. The unaided four-frequency average
(0.5, 1, 2, and 4 kHz) AC for the Attract group was
60.8 dB HL, with an improvement to 30.6 dB HL for
mean aided thresholds (mATs) across the same frequen-
cies. The Sophono group’s unaided four-frequency aver-
age AC was 57.8 dB HL, with improvement to mAT of
29.8 dB HL. Aided thresholds from both devices were
poorer in the high frequencies (4 and 8 kHz) than at 1 kHz
(Fig. 1). There was no significant difference (Mann-
Whitney U test) between Attract and Sophono mATs
at any of the individual frequencies.
The speech discrimination results for all recipients are
shown in Figure 2. As expected, speech perception scores
for both devices improved in quiet and in noise. There
was greater variation in individual results when testing in
1526 H. R. F. POWELL ET AL.
Otology Neurotology, Vol. 36, No. 9, 2015

Copyright © 2015 Otology Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
TABLE1.Patientdemographicsandcharacteristics
Patient
Ageat
SurgeryDevice(s)
Hearing
LossEtiology
Speech
Perception
Testing
Follow-up
Interval
Overall
Satisfaction
(0¼Very
Dissatisfied;
10¼Very
Satisfied)
QOL
Improved?
Hours
Used
per
Day
Doesthe
Processor/
Magnet
Fall
Off?
IfSo,
HowMany
Times
perDay?a
Recommend
to
Others?
112yr8moBilateralBAHA
BP110
RCHL,LmixedLVASþMondiniBKB6mo,19d10Yes8NoN/AYes
245yr9moUnilateralBAHA
BP110
UnilateralSNHLIdiopathicBKB9mo,14d9Yes8Yes2Yes
37yr5moBilateralBAHA4RCHL,LmixedBilateralLVASþ
hypoplasticSCs,
LeftMondini
BKB5mo,1d10Yes8Yes3–4Yes
411yr1moUnilateralBAHA4UnilateralCHLAtresiaBKB4mo,9d10Yes4–8YesDependson
activities
Yes
58yr9moBilateralBAHA4BilateralCHLPrimaryciliary
dyskinesia
BKB1mo,9d9Yes4–8Yes(Notanswered)Yes
68yr8moBilateralBAHA
BP110
BilateralCHLEACstenosisNU-CHIPS8mo,4d10Yes8Yes5–10Yes
Mean15yr9mo177d
711yr8moUnilateralSophono
Alpha2
BilateralCHLChronicotitis
externa
BKB11mo,14d10Yes8YesVeryoccasionallyYes
Alpha2
UnilateralCHLAtresiaBKB5mo,18d7Yes4–8Yes3–5Yes
Alpha2
UnilateralSNHLCongenitalCMVBKB1yr,4mo,2d10Yes8Yes5Yes
Alpha1
BilateralCHLBilateralatresiaBKB2mo,18d7Yes2YesOccasionallyYes
Alpha2
BilateralmixedDownsyndrome
(chronicotitis
media)
NU-CHIPS4mo,27d9Yes4–8Yes2/wkYes
125yr8moBilateralSophono
Alpha2
BilateralCHLBilateralatresiaNU-CHIPS9mo,22d9Yes8Yes!5Yes
Mean11yr1mo255d
BKBindicatesBamford-Kowal-Bench;NU-CHIPS,NorthwesternUniversityChildren’sPerceptionofSpeech;LVAS,largevestibularaqueductsyndrome;SCs,semicircularcanals;EAC,
externalauditorycanal;CMV,cytomegalovirus;BAHA,bone-anchoredhearingaid;QOL,qualityoflife;CHL,conductivehearingloss;SNHL,sensorineuralhearingloss.
a
Clients’actualresponses.Alldevicesfittedbilaterallywerefittedsimultaneously.
TWO TRANSCUTANEOUS BONE-ANCHORED HEARING DEVICES 1527

noise, particularly in the Attract group. One patient had
lost interest in testing for the aided speech in noise test
and scored 0. Unfortunately, they were unable to attend
another appointment. Mean speech discrimination scores
are shown in Figure 3. There was no statistical difference
between the speech discrimination scores for the two
devices in quiet ( p ¼ 0.33) or in noise ( p ¼ 0.87). Using
the Mann-Whitney U test, no systematic difference was
found in scores at 55 dB SPL aided ( p ¼ 0.57) or at 65 dB
SPL aided in noise ( p ¼ 0.87) for the two devices.
All patients/parents completed the questionnaire fully.
All Sophono and Attract users reported that their devices
had improved their QOL. The overall satisfaction scores
are shown in Figure 4. Table 1 shows the intervals
between device fitting and audiologic testing, as well
as clinical outcome results from the questionnaire.
Eleven of the 12 recipients described problems with
the device falling off their head, but despite this problem,
all recipients reported that they would recommend the
device to others with similar hearing difficulties. One
patient in the Sophono group had developed a pressure
sore at the time of follow-up and was therefore using the
device for less than 2 h/d. Another Sophono patient
reported that Magnet 2 was prone to falling off, but
Magnet 3 was uncomfortable. In the Attract group,
one patient reported that the device still fell off despite
using the stronger magnet, and another reported that the
magnet stayed on but the processor would detach.
DISCUSSION
This is the first study to compare the outcomes for two
TBCIs. It is also the first to present hearing results for the
Attract device in the pediatric population. We showed in
our study that the results were similar for the two devices,
with no significant difference in the mATs or the mean
speech discrimination scores.
Figure 1 shows mean aided audiograms for both
devices. Although low and mid frequencies came up
to the normal to mild hearing loss range, 4 kHz and
8 kHz showed only limited improvement for both devi-
ces. Our mATs at 4 kHz (Attract, 49 dB HL; Sophono,
Baha Sophono
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●●●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
0
25
50
75
100
Unaided 55 Aided 55 Aided 65:65 Unaided 55 Aided 55 Aided 65:65
Score
FIG. 2. Speech discrimination results for all recipients.
FIG. 1. Mean thresholds for the two devices. AC unaided indicates masked air-conduction thresholds for affected ears only (i.e., does not
include the normal ear thresholds for patients with a unilateral loss); BC, bone conduction thresholds for the better ear.

44 dB HL) are comparable to previous studies for both
the Attract (51 dB HL [14]) and the Sophono (38 dB HL
[8]; 49 dB HL [15]). Despite poor high-frequency ampli-
fication, mean speech perception for both devices at
55 dB SPL was very good (Attract, 89%; Sophono,
82%; Fig. 3). The presentation level of 55 dB SPL is a
soft conversational level, which is therefore difficult to
compare with previous studies, which have used louder
presentation levels of 65 dB SPL (15) or 65 dB HL (8).
Our results for the Sophono are comparable to results
from previous series (8,15,16). Hol et al. (15) compared
the Sophono with the percutaneous BAHA in a pediatric
population. They reported mATs at 0.5, 1, 2, and 4 kHz.
Their mean unaided AC threshold was 58 dB HL (the
same as ours), with a mAT of 36 dB HL. Our patients had
a slightly better mAT of 29.8 dB HL. Predictably, the
percutaneous BAHA patients in their study performed
5 to 10 dB better at 4 kHz than their Sophono patients.
This is caused by soft tissue attenuation with transcu-
taneous devices, which is known to mainly affect the high
frequencies (16,17).
Siegert and Kanderske (8) reported on 20 auditory
atresia patients (adults and children) implanted with the
Sophono device who had a mean unaided pure-tone
average AC of 58.7 dB HL, improving to a mAT of
28.7 dB HL. This is comparable with our results for both
Sophono and Attract. Sylvester et al. (18) reported on
18 Sophono patients with a variety of etiologies. Four
bilateral conductive hearing loss patients with a mean
(0.25–8 kHz) AC threshold of 52 dB HL had a mAT
improvement of 21.9 dB. Our results, for Sophono
patients with conductive hearing loss only, were calcu-
lated for comparison and are similar: a mean AC of
55.2 dB HL and a mAT of 32.5 dB HL. The largest cohort
of patients in the article by Sylvester et al. (18) had
bilateral mixed loss, and the device was of marginal
benefit with a mAT improvement of only 6.2 dB. Unlike
other studies, they did not block the good ear in patients
with a unilateral loss when testing in free field and
therefore did not have results for these patients.
Results for the Attract have recently been published in
a multicenter study of 27 adults (14). The mean preop-
erative AC (0.5, 1, 2, and 4 kHz) was 55.7 dB HL and
improved to 37.3 dB HL. This improvement was more
marked in the lower frequencies, similar to our findings.
The better mAT of 30.6 dB in our predominantly
pediatric population is likely caused by thinner soft tissue
and less attenuation of vibration in children. This multi-
center study also performed speech perception testing of
monosyllabic words in quiet at 50, 65, and 80 dB SPL,
with improvement by 50.0%, 46.4%, and 24.2% from the
unaided condition, respectively. Our study reported, for
FIG. 4. Overall satisfaction scores. Patients (or parents) were asked to rate their overall satisfaction with the device on a scale from 0 (very
dissatisfied) to 10 (very satisfied), with 5 being no difference with or without the device.
FIG. 3. Mean speech perception scores in three different conditions.

sentences at 55 dB SPL, a mean improvement for Attract
of 70% (from 19% to 89%). The greater improvement
may be related to the same factors that influenced the
aided thresholds, particularly in the high frequencies (less
attenuation in our predominantly pediatric population),
and additional context in a sentence test compared with
words.
Aided thresholds for the percutaneous BAHA (15)
were better in the high frequencies than our results for
both these transcutaneous devices. Despite the poor high-
frequency amplification (Fig. 1), speech perception
scores showed good improvement from the unaided
condition at a soft conversational level. Our study
showed a very low correlation between aided thresholds
at individual frequencies (0.5–4 kHz) and aided speech
discrimination scores in quiet and in noise (0 dB SNR).
This does not rule out the possibility of a significant
correlation in a larger sample; however, it suggests that
caution should be used when making inferences about
speech discrimination with TBCIs when testing aided
thresholds alone (19).
Other studies (15,18) have reported either speech
reception thresholds (SRTs) or speech perception scores
at alternative intensity levels. Sylvester et al. (18)
reported on 18 Sophono patients, with speech perception
tested at 65 dB SPL unaided (15.3%) and aided (76.8%)
and at 65 dB signal level and 60 dB (HL/SPL not speci-
fied) noise level; SNR, À5 (54.5%). Hol et al. (15)
reported on six Sophono and six percutaneous BAHA
patients, with mean word recognition scores of 84% and
91%, respectively, at 65 dB SPL. Our speech perception
scores at 55 dB SPL were comparable to those of Hol
et al. (15) at 65 dB SPL, 82% for Sophono and 89% for
BAHA Attract (Fig. 3).
As most of our subjects were children, we carried out
speech perception testing that was shorter and less oner-
ous than SRT testing. Also, children are less adept at
using linguistic redundancy to decipher partially heard
speech near threshold, such as in SRT measurement (20).
Therefore, we believe that measuring speech scores at
soft (55 dB SPL) and average (65 dB SPL in noise)
conversational levels is more true to life testing than
SRT and gives a better understanding of a patient’s
ability to hear in common listening situations, as was
the intention of Bench et al. (21) when designing the
Bamford-Kowal-Bench/Australian Version sentence tes-
t. Although our outcomes are from a predominantly
pediatric population, we think that the adult results
add to the study and are worth reporting.
All our TBCI recipients (or their parents) reported
improvement in their QOL (Table 1). Both groups
reported benefit with their TBCI when compared with
previous conventional hearing aids. The overall satisfac-
tion scores are shown in Figure 4. All recipients except
one Attract user reported problems with the device falling
off the head (Table 1). Despite this problem, every
recipient in our study reported that he or she would
recommend it to others with similar hearing difficulties.
The patient in the Sophono group who had developed a
pressure sore reported that, despite this, the device was
more convenient than using a headband, and hence, the
patient intended to resume more frequent use once the
sore had completely healed. The manufacturers are
steadily addressing these issues and the balance between
comfort and stability.
This evolving area of TBCIs is in its infancy. Our study
has small numbers; however, we present early outcome
results, which are useful for counseling potential device
recipients and their families. The Sophono device is Food
and Drug Administration approved for magnetic reson-
ance imaging up to 3 T and causes less signal void than
the BAHA Attract, which is approved up to 1.5 T. If BC
hearing thresholds deteriorate, then these TBCIs may not
have sufficient power to adequately aid the recipient;
however, with the Attract device, there is the option to
convert to the percutaneous BAHA. Further studies with
larger numbers are needed. We acknowledge that testing
with one ear occluded, and monaurally if binaurally
aided, is not a true reflection of a patient’s day-to-day
listening situation; however, this was deemed the best
way of comparing the two groups. The high-frequency
limitations when compared with the percutaneous BAHA
remain; however, these devices provide good speech
perception and QOL outcomes for patients wanting a
transcutaneous bone-anchored solution.
CONCLUSION
Our study is the first to compare the Sophono and
BAHA Attract devices. Both systems provide audiologic
benefits, with unaided PT averages of approximately
60 dB HL improving to a mAT of approximately
30 dB HL for both devices. Aided speech discrimination
scores at 55 dB SPL and in noise at 65 dB SPL (SNR, 0)
showed considerable overall improvements compared
with the unaided 55 dB SPL situation. There was no
statistically significant difference in aided thresholds
or speech discrimination scores between the two devices.
All patients (or their parents) reported improvement in
QOL with their device and would recommend their device
to others in a similar situation. These findings are import-
ant for clinicians—to enable counseling of patients and
their families on the outcomes of these two TBCIs.
Acknowledgments: The authors thank the Graham Fraser
Foundation.
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