The document discusses the history, components, types, needs, candidacy, and surgery of bone anchored hearing aids (BAHA), which transmit sound to the cochlea via bone conduction by bypassing abnormalities of the outer and middle ear through an implanted titanium fixture. It traces the development of BAHA from its origins in the 1950s to current digital processors. BAHA consists of a titanium screw surgically implanted in the skull that protrudes a titanium abutment connecting to an external sound processor.

1. BONE ANCHORED HEARING
AIDS (BAHA): HISTORY, NEEDS
& CANDIDACY
PRESENTER: ANUJ KUMAR NEUPANE
LECTURER: MS. GEETHA C.

2. Introduction
History
Components
Types of BAHA
Need of BAHA
Candidacy for BAHA devices
Audiological indications
Otological indications
Contraindications
Surgery& its complications
References
C
O
N
T
E
N
T

3. INTRODUCTIO
N
• Mostly the individual with hearing impairment are fitted with hearing aids with the help of
custom ear mould
• Few hearing not possible
Reasons :
1)Stenosis of the EAM
2) Frequent CSOM
3) Mastoidectomy resulting wider EAM
4) Anotia

4. • Requirement of rehabilitation with new technology than conventional hearing aid
• BAHA – bypasses the pathologies at outer and middle ear
• BAHA is the type of hearing aid technology which is attached to an implanted titanium
abutment through which sound is transmitted to cochlea via bone conduction similar, as
tuning fork, bypassing EAM and middle cavity.

6. Scheme of BAHA
Bone conduction stimulation explained via different theories as:
 OSSEO TYMPANIC MODE
• Cannot reach inner ear due to obstruction at the level of outer or middle ear structures
• Thus other two modes of bone conduction are important for BAHA

7. • Herzog and Krainz (1926)
• With the alternating force cochlear capsule gets expansion and
compression.
• Bulging of cochlear capsule at the level of round window takes place as
its more compliant and cochlear fluid is not compressible.
• Variation in the shape of basilar membrane leads to the hair cells
excitation.
 COMPRESSION MODE

8.  OSSICULAR LAG OR INERTIAL MODE
• Loosely coupled ossicles
• Different timing in vibration of the temporal bone and ossicles (Barany,1938)
• Ossicular movements get lagged.
• BC sensitivity at mastoid placement is maximum (lateral placement vibrates the
skull in the direction of ossicular movement)
• Minimum for forehead placement (frontal placement vibrates the skull
perpendicular to their movement)

9. HISTORY
OF
BAHA
1) Per Ingvar Branemark,1952
• Discovered the formation of osteocytes around the titanium screws
kept uninterrupted in bone
• Stable anchor with no connective-tissue in between.
• Connection of living bone with implant at level of titanium is known as
Osseo integration.
• Helped invention of percutaneous titanium implants came into
existence.
2) Per Ingvar Branemark, 1965
• Osseo integration was successfully applied in craniofacial and
dental reconstructive surgery.
3) Tjellstrom et al, 1974
• Osseo integrated titanium implant at the level of mastoid
• Direct bone conduction

10.  1977
BAHA was used with osseointegration
 1980 (Hough and Xomed- Treace)
Transcutaneous approach was introduced for BAHA.
 1987
Transcutaneous BAHA got commercially available
 1996
Introduced as rehabilitative measure for CONDUCTIVE AND MIXED
HEARING LOSS.
 1997
Food and Drug Administration (FDA), US cleared BAHA for clinical
usage.
HISTORY
OF
BAHA

11.  1999
• FDA approved it for use by children ≥5 years of age
 2000
• FDA approved bilateral BAHA fitting.
• Baha Compact for clinical usage
• Smaller to Classic by 33%
• Present automatic Gain Control & Output compression
• Shielded well from telephone signals
• Less powerful
 2002
• FDA approved BAHA for unilateral deafness.
• Baha Softband came into existence for peadiatrics (<5yrs).
HISTORY
OF
BAHA

12.  2004
• BAHA Divino in clinical usage
• Digital sound processing system
• Directional microphone
• Automatic Gain control output compression.
 2005
• Entific Medical Systems was purchased by Cochlear Limited
Renamed BAHA as BONE ANCHORED IMPLANT
• Elimination of its connection with hearing aids
• Highlight as a Surgical Implant
• Late of 2005, Medicare re-categorized BAHA as PROSTHESIS.
HISTORY
OF
BAHA

13.  2008
• Commercial availability of Divino, Intenso and Cordelle
• Cordelle used for Severe Hearing Loss.
• Presence of induction telecoil receiver
Intenso
• More powerful BAHA
• Clarity in listening environments with minimum acoustic feedback.
 2009
• Cochlear BAHA
• Latest BAHA processor
• First programmable BAHA as BP100 with compatibility to Bluetooth and
iPod.
• Oticon brought Ponto pro for both adults and children
HISTORY
OF
BAHA

14. Latest BAHA 210 Abutment has concave profile preventing skin from overgrowth.
HISTORY
OF
BAHA
 2010
• BAHA 210 had concave shaped abutment preventing skin from overgrowth

15. BAHA manufacturing
companies
Different models available
CochlearTM  Cochlear™ Baha® BP100
 Baha Intenso™
 Baha® Cordelle II
 BAHA 3
 BAHA 4 Attract
 Baha 5 Attract
Oticon Medical  Oticon Ponto
 Ponto Pro
 Ponto Power Pro
 Ponto Plus
Sophono  Sophono Alpha 1 (S)
 Sophono Alpha 2 with magnetic
processor
Medel  Medel Bonebridge
Different companies and models of BAHA

16. Components
BAHA consists of 4 components
1) Titanium screw
2) Titanium abutment
3) Ear level sound processor
4) Snap-lock coupling
1Sound Processor
2Titanium Abutment
3Snap-Lock Coupling
4Titanium Fixture
5Temporal Bone
6Skin

17. a) Titanium Fixture (Osseointegration)
1. Surgically a small titanium implant is fitted in the mastoid
2. Osseointegration.
3. Strength of osseointegration determines the long-term success of Baha
rehabilitation.
4. Corrosion-resistant oxide layer by Titanium on the surface of the implant
enhance osseointegration.
1Sound
Processor
2Titanium
Abutment
3Snap-Lock
Coupling
4Titanium
Fixture
5Temporal Bone
6Skin

18. b) Titanium Abutment
• Percutaneous titanium abutment is attached to the fixture
• Processor is connected to the protruding part of the abutment.
• Secure retention of Baha sound processor by Osseo integrated
implant and abutment system
• Vibrations are transmitted from the sound processor via the bone conduction to
the cochlea.
Previously, a magnetically driven osseointegrated device was in use, but was
withdrawn due to technical difficulties with the transcutaneous device (Xomed’s
Audiant Bone conductor).
1Sound
Processor
2Titanium
Abutment
3Snap-Lock
Coupling
4Titanium
Fixture
5Temporal Bone
6Skin

19. c) Snap-Lock Coupling
• Clasp in the implanted abutment and sound processo
• Can be disconnected if it creates impact on tissues around or the
impant.
1Sound
Processor
2Titanium
Abutment
3Snap-Lock
Coupling
4Titanium
Fixture
5Temporal Bone
6Skin

20. d) Sound Processor

21. e) Accessories
i) Audio adapter (present for Divino/Classic300/Classic BAHAs in CochlearTM).
Via this one can connect music system, MP3, MP4, etc directly to the sound output.

22. ii) Telecoil (present in BP100 BAHA for CochlearTM)
Helps in better perception while using telephone or in case of presence of
induction loop.

23. iii) FM receiver (present in CochlearTM).
In presence of FM system enclosed such as classrooms, FM receivers in Baha
can play a vital role to avoid noise.

24. iv) Baha Softband (present in CochlearTM).
• Elastic band for infants and young children
• Baha sound processor to inact without surgeries for implantation.

25. v) Baha Safety line (present in CochlearTM)
• Ties the processor of the implant to the collar of upper wear
• Safe from damage or lost.

26. vii) Test Rod and Test Band (present in CochlearTM).
• Pre-operative equipment
• Judge out which side the implants to be placed
• Helps to demonstrate the individual regarding sound processor,
coupling and abutment.

27. viii) App controllable
• Present in Oticon Streamer Pro 1.3 A (Open)
• Allows access to sound from loop systems for hearing aids that don’t have the T programme
• An Oticon radio aid receiver can be connected so that it can pick up sound from a radio aid
transmitter

28. ix) Cochlear wireless accessories
• Present in Lets Baha 4
• 7 metre range (stated in the manufacturer's specification)
• Also include an app. (Apple and Android)
WIRELESS REMOTE
WIRELESS PHONE CLIP
WIRELESS MINI MIC

29. Types of BAHA
Two different BAHA uses different vibration reluctance transducer to excite the skull bone directly
1) Percutaneous BAHA
2) Transcutaneous BAHA
VIDEO

30. 1) Percutaneous BAHA
 Percutaneous BAHA include a transducer to vibrate the mastoid bone in an external unit with
a direct physical link through the skin to the anchor screw (Tjellstrom and Granstrom, 1995).
 A titanium screw is surgically anchored in the mastoid and protrudes through the skin.
 Attached to this exposed screw is a removable bayonet connector and a vibratory
transducer.
 This approach requires good hygiene but provides efficient vibrational transmission.
1-Mastoid bone,
2- soft tissue,
3-titanium fixture,
4-titanium abutment,
5- bayonet coupling,
6- percutaneous transducer.

31. 1) Transcutaneous BAHA (Hough et al., Hough and McGee, 1995)
 Transcutaneous BAHA uses an external magnetic field to cause a magnet anchored
to the mastoid under the skin to vibrate.
 This is surgically attached to the mastoid bone via a screw.
 The bone-anchored magnet is stimulated electromagnetically.
 Because of the coil-to-magnet distances dictated by the skin thickness, these
devices provide lower efficiency and poorer frequency response.
 As a consequence, these devices are currently not marketed.
1. Mastoid bone.
2. Soft tissue,
3. Titanium anchored magnet,
4. Transducer.

32. Study by Hakansson et al 1984
• Comparison of electroacoustic performance of the BAHA classic 300 and transcutaneous bone
conduction implant in cadaver
• Vibration response given were measured at ipsilateral and contralateral cochlear promontories
by doppler vibrometer
Hakansson et al
1984

33. • Transcutaneous bone conduction implant gives 5 dB higher maximum output level
and has a slightly lower distortion than the classic-300 at the ipsilateral
promontorium at speech frequencies.
• At the contralateral promontorium, the maximum output level was considerably
lower for the BCI than for the classic-300 except in the 1-2 khz range, where it was
similar.

34. Based on level of processor:
TWO types
A. Body Level Device
B. Ear Level Device

35. B. The Body worn Device by Cochlear Americas (Englewood, CO)
Cordelle BAHA
• Powerful bone anchored device
• 10-15 dB more output at higher frequencies
• 5-7 dB more output at lower frequencies.
• Also the resonance frequency was kept at lower frequency so as to incorporate the
individual with moderately severe sensory-neural hearing loss whose residual hearing
would be at low frequency.

36. • Classic 300 BAHA by Entific Medical Systems
• Basic ear level device
• Consists of : 1) Volume control
• 2) Gain control and continuous tone control for low frequencies
• 3) N and L position switch for two different high frequency response
• 4) E switch for connecting electrical input directly (internal mic gets off)

37. The Baha Divino by Cochlear Americas (Englewood, CO)
• Includes digital technology
• Directional Mic with 2 programs for speech in noise and quiet
situations
• Adjustable AGCo that avoided distortion for improvised sound quality
in adverse loud situations.
Divino can be connected to external systems such as TV, mobile phones, IR
systems with the help of electrical input.

38. Cochlear Baha BP100 (Currently Used)
by Cochlear Americas (Englewood, CO)
Features :
1) Dual Layer Protection
• Limit the risk of processor breakdown.
• A tight seal protects the transducer from moisture entering from the snap coupling.
• Re-engineered with transducer suspensions and mechanical stops in the snap coupling
• The changes prevent excessive movement in any direction,

39. 2) Transducer stability –
• At the core of the Baha sound processor, the transducer creates the
vibrations that transfer the sound through the skull bone to the inner ear.
• Transducer is very precise component with the air gap inside the vibrator
measuring 50 – 70 micrometers.
• Transducer is sensitive to excessive force that could result in its collapse.

40. Other features
1) Compatibility – FM systems, Direct Audio Input for phones, and
other audio sources.
2) Wind noise protection

41. Ponto and Ponto Pro by Oticon Medical
Features
a) Automatic Adaptive Multiband Directionality
• In noisy restaurants or other crowded areas, the directionality
system helps to hear people speaking in front of more clearly.
• Moving across the environment, Ponto shift itself to the best setting
automatically.
b) Tri-State Noise Reduction
• Helps suppressing the noise by identifying if the signal consists of
speech alone, only noise or both in mixture.

42. 3) Wind Noise Reduction
• Better listening in outdoor situations.
4) Learning Volume Control
• Presence of memory device
• Remembers the volume control setting used consistently for period of
time
• Automatic changes as per the similar situation given.

43. BONEBRIDGE - by Medel, Innsbruck, Austria
• A new era in bone conduction stimulation
• Semi-implantable hearing system
• Implant is positioned completely under the skin.
• Implant receives the signals from an external audio processor, which is worn
comfortably under the hair.
The system consists of an external and an internal component.

44. EXTERNAL
Audio processor
• Fully digital signal processor.
• Held in position on the head by magnetic attraction
• Can be worn discretely and comfortably under the hair
• Consists of the battery and the microphones
INTERNAL
Implant
• Positioned completely under the intact skin
• Has magnet that holds the audio processor in place above the
implant.

45. Merits of BONEBRIDGE
 Undamaged cosmetically tempting skin.
 Avoids skin complications.
 Less visible as it’s totally below skin, thus audio processor can be kept below the hair.
 Ear canal is not closed like conventional hearing aids.
 Gentle and brief surgical procedure (0.5-1 hr) with only external units replaceable.
 Audio processor is replaceable, so one can exchange it with the advancement of technology.
 Can be activated within 2-4 weeks of post-surgery by audio processor fitting.
 User friendly audio processor with battery to be replaed once in 5-7 days.

46. Different companies and models of BAHA
CochlearTM
Australia
MODELS Technology Direct audio input
BAHA Intenso
• Advanced digital
technology
• Less feedback Present
BAHA Cordelle
• Body worn device
• Powerful BAHA
• 10-15dB more output for
higher frequencies
• Less feedback and
distortion
BAHA 3 /
BAHA BP100
Advanced
digital signal processing

47. CochlearTM
Australia
MODELS
BAHA BP110
power
first high
power sound
processor
with
advanced
automatic
signal
processing for
greater loss
individual
more
than 50%
improved
speech
understandin
g in noise
(Snik et al,
2002)
Automated
directionality
automatic
noise
reduction
BAHA 4
Attract
advanced
signal
processing
technology by
using a smart
classifier that
scans your
listening
environment
magnetic
connection
2.4GHz
wireless
technology
comfortable
and easy to
use hearing
system
BAHA 5
Attract
advanced
hearing
technologies
smallest
sound
processor

48. OTICON MEDICAL
MODELS
Ponto
automatical
ly adjust to
the
situation
and the
environme
nt and
provide the
superior so
und quality
Tri-state
Noise
Reducti
on
Wind Noise
Reduction
3-4 mm
titanium
implant
Ponto Plus
a new powerful
transducer, the
innovative Inium
feedback shield
and the latest
Bluetooth 2.4
GHz wireless
technolog
Less
whistling
and fewer
artificial
sounds
first new Inium Sense highly Pending FDA

49. MODELS
Sophono Alpha 1 Abutment-free,
magnetically coupled
bone anchored hearing
aid
Automatic noise
reduction and feedback
suppression
Available with direct
audio input for use with
FM receiver, telecoil
and other external
accessories
8 channels
16 frequency bands
4 programs
Customizable program
switching and low
battery warning tones
Sophono Alpha 2 Abutment-free hearing
with no sacrifice in
performance
smallest implant on the
market (2.6 mm high)
8 channels
16 frequency bands
4 programs
WDRC
Sophono

50. MODELS
Medel Bonebridge • Semi-implantable
hearing system
• Implant is positioned
completely under the
skin.
• Fully digital signal
processor.
• Held in position on
the head by magnetic
attraction
Remote Control
(changing programs,
adjust volume)
Medel

51. Indication for Baha and Selection Criteria
FDA criteria
• Oticon, Sophono, Medel follows FDA criteria,
• However cochear has slight modifications from that of FDA criteria

52. AUDIOLOGICAL EVALUATION
Conductive hearing loss
FDA OTICON COCHLEAR MEDEL SOPHON
O
All conductive hearing
loss present till up to
45 dB HL.
Upto
55 dBHL
with Ponto
Pro
Candidates with an air-bone gap of
more than 30 dB will have significant
improvement with Baha System,
than conventional hearing aids.
(Snik et al, 2005; Hol et al, 2005;
McDermott et al, 2002).
Same as
FDA
Same as
FDA
• For bilateral implantation, average bone conduction should be ≥ 45 dBHL
• Symmetrical between the ears i.e the difference can be 10 dB at 0.5 KHz, 1 KHz, 2 KHz and 3
KHz between the ears.
With use of phonetically balanced CVC words, SIS to be ≥ 60%.

53. Mixed hearing loss
• (E.g. cochlear otosclerosis, genetic causes, noise trauma, ototoxicity, presbycusis)
• BAHA directly stimulate the cochlea, it bypasses the conductive component and gives
additional amplification to compensate for the sensorineural element.
FDA OTICON COCHLEAR MEDEL SOPHON
O
 Average BC
threshold up to 45
dB HL.
Same as
FDA
Candidates with an air-bone gap of
more than 30-35 dB plus
sensorineural component up to
mild-to moderate level to be fitted
with BAHA.
(De Wolf 2011).
Same as
FDA
Same as
FDA
SIS of ≥ 60%.(Hankansson et al 1990)

54. FDA
(approved on
September of 2002)
OTICON COCHLEAR MEDEL SOPHONO
 Unilateral deafness, PTA of AC (0.5 KHz, 1 KHz, 2 KHz and 3 KHz) of normal ear to be ≤ 20-25 dB HL.
 Individual who are candidate of CROS but doesn’t want to go for it (Snik et al, 2004).
Single sided Deafness

55. OTOLOGICAL INDICATIONS
 Skin allergies
Allergies in the outer ear and/or the ear canal aggravated by the placement of
an ear mold can be compensated with the usage of BAHA device as it
maintains open ear canal. (Evans et al, 2007)
 Congenital malformations
For most candidates with congenital ear malformations, surgical intervention
or a bone-conduction (BC) hearing aid is often prescribed because an AC
hearing aid is simply not an option.
Congenital malformations can be atresia of M.E or outer ear/ innate
deformities with agenesis, microtia, anotia etc. (Evans et al, 2007)

56. • Draining ears
Individual with hearing impairment having CSOM where earmould couldn’t be used
as it enhances the infections.
With a Baha System, the ear canal remains open at all times, thus allowing the ear
to dry (Snik et al, 2005; Sheehan and McDermott. 2010).
• Ear canal stenosis
Individuals with stenosis of the ear canal are not suitable for a surgical intervention,
and the use of conventional hearing aids can also be difficult due to the presence of
an ear mold. With a Baha System, the ear canal is bypassed.
• Previous ear surgery
Candidates who have had previous surgeries using, for example, a canal wall down
procedure, may find it difficult to wear an ear mold without feedback problems. The
Baha System is a good solution because an ear mold is not required.

57. • Radical cavity
Patient who have undergone mastoidectomy with wider EAM resulting in
often acoustic feedback.
• Syndromic hearing losses
Treacher Collin Syndrome (Oliveria et al 2013)
Goldenhar Syndrome (Marres et al, 1995; Hol et al, 2010;)
Downs Syndrome (Sheehan et al, 2006)
• Unilateral total deafness caused congenital/acquired, e.g. post-
neurinoma surgery where hearing couldn’t be preserved;
neurodegenerative disease; ototoxicity etc

58. Contraindications:
• BC threshold of ≥ 60 dB HL in an average at 0.5 KHz, 1 KHz, 2 KHz and 3 KHz
• Clients with mental retardation
• Less cooperative clients such as small children (lower age limit for Baha use at
US is 5 yrs.), drug addicts, mentally ill patient etc.
• Patients vulnerable to increased risk of infection.
• Patients having allergic reaction to the implant.
• Rejection of the device due to subjective factors like cosmetic appeal.

59. • Poor hygiene.
• In case of less bone volume and density for successful Baha abutment fixation.
• Obliteration of the cochlea, auditory nerve, auditory cortex. This can be revealed by CT
scan, MRI etc. MRI is a better technique for finding ossified cochlea, nerve hypoplasia
and CNS anomalies.
• Also need to assess family dynamics and their expectations on the device plus psycho
social aspects.

60. Surgery for BAHA
• Less difficult one
• However precise care
• Inclusion of multi-disciplinary team with at least otologist and audiologist.
• Different stages of surgeries includes as:

61. TYPES OF SURGERY
One-Stage Surgery
Selection criteria
• Good bone quality
and
• thickness > 3 mm
Two-Stage Surgery
Selection criteria
• Compromised or soft bone
• Bone thickness < 3 mm
• In conjunction with other surgery
• (e.g. Acoustic Neuroma removal)

62. Step I: Placement of BAHA.
50 – 70 mm from the ear canal
One-Stage Surgery

63. Step II: Dermatome takes up the skin flap

64. Step III:Removal of soft tissues

65. Step IV:Exposing the periosteum

66. Step V: Guide drill used
3-4 mm widening drill

67. Step VI: Drill countersinkused

68. Step VII: fixture plus abutment placed

69. Step VIII: Skin punched

70. Step IX: Skin closed

71. Step X: Healing cap over the punched area plus dressing.

72. Surgical follow-up (5-7 days)
Remove the dressing and
assess the wound site. If
healed, no further dressing
is required. If not healed, place
a new dressing
10-14 days
Remove sutures after
if incision is sufficiently healed

73. Fitting the sound processor
4 weeks after surgery
• Check and clean skin.
• Fit the selected Sound
Processor Magnet and
sound processor.
• Orient the patient
regarding the handling
of sound Processor.
Follow up (once or twice a year)
• Audiological assessment after
fitting sound processor.
• Examination of skin and tissue.

74. Surgical follow-up
• Remove sutures, if healed (1 week)
• Osseointegration period (3–6 months)
Two-Stage Surgery
First stage
Place implant and cover screw

75. Second stage
Remove the cover screw and place the implant magnet.
Surgical follow-up (5-7 days)
Remove the dressing and
assess the wound site. If
healed, no further dressing
is required. If not healed, place
a new dressing
10-14 days
Remove sutures after
if incision is sufficiently healed

76. Follow up
Fitting the sound processor
4 weeks after surgery
• Check and clean skin.
• Fit the selected Sound
Processor Magnet and
sound processor.
• Orient the patient
regarding the handling
of sound Processor.
Follow up (once or twice a year)
• Audiological assessment after
fitting sound processor.
• Examination of skin and tissue.

77. Surgical complications of BAHA
• Implant continues to rotate when seated.
• Inaccurate location of the implant
• Inappropriate handling of the implant
• Exposure of Dura Mater or Perforation of the Sigmoid Sinus
• Subdural Hematoma
• Inability to create a thin, hairless, immobile flap due to thin skull
tissue. (Wazen et al, 2008)

78. Post-surgery complications
 Less post-surgery complications such as local inflammation/infections due to
Osseo integration failure has been reported.
 The skin reactions after surgery has been classified by Holgers into:
0 - No irritation
1 - Slight redness
2 - Red and moist, no granulation tissue
3 - Red and moist with granulation tissue
4 -Revision of skin penetration necessary (Kraai et al 2011)
 Serious post-surgery complication is the loss of osseointegrated fixture at
temporal bone level which can be due to trauma (mostly in children), poor
hygiene etc.

79.  Overgrowth of the soft tissue and drooping due to gravity may obstruct in
fixing BAHA transducer with the abutment
 Percutaneous implants may get affected up to 10% due to the Osseo
integration loss, bone disease, trauma, infection, or radiation.
 Clients affected by intracerebral abscess & by metastatic carcinoma post
BAHA implant have been reported earlier which are rare in nature.
However, as they are fatal, client should undergo CT/MRI.
 Post Baha pain is a rare condition.

80. Most of these complications can be treated with
antibiotics and also steroid, however, 1 to 2% needs
surgical intervention such as correction of the
placement, removal of the BAHA fixture. (Falcone et
al, 2008)

81. Conclusion
• Appropriate candidacy criteria maintained and surgery done, BAHA can be
effective.
• Better than conventional BC hearing aids.
• Bilateral BAHA is an option for bilateral hearing loss for binaural sound processing.
• BAHA can be used unilaterally in one sided deafness as transcranial CROS that
reduces HSE in an effective manner.
• However lack of competition at commercial level and high cost are the major
disadvantage of this hearing implant device.

82. References
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principles, indications, and long-term clinical results. Otolaryngologic Clinics, 28,
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J. 1994 Feb;73(2):112-4.

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