Design innovations of the Cochlear™ Baha® BP100 Sound Processor

Design innovations of the
Cochlear
Baha ® BP100 Sound Processor
Mats Dotevall, Director of Design & Development at Cochlear Bone Anchored Solutions, Gothenburg, Sweden
ABSTRACT
The Cochlear Baha ® BP100 Sound Processor is a result of new thinking within the bone
conduction hearing industry. The design is based on the results of a comprehensive international
study of Baha user and Baha professional needs. The BP100 introduces a range
of unique design innovations and utilises new technology never before available in bone
conduction hearing implants. This paper presents Cochlear’s objectives when designing the
BP100 and how these design choices meet the needs of Baha users.
INTRODUCTION
Before setting out to create the Baha BP100, Cochlear identified the
needs of Baha users and professionals. Hearing performance was
indicated as the number one requirement and with 25% improved
speech understanding in noise1-6 the BP100 is the benchmark for
hearing performance in bone conduction. But our comprehensive study
highlighted other requirements that are vitally important to Baha
users and Baha professionals. The design objectives were clear: provide
industry leading usability and functionality with design features that
deliver real benefits to our customer and produce a reliable product
that performs in demanding weather conditions and challenging
environments. These key objectives were then broken down into
micro-goals, which when combined, formed the basis for a robust and
innovative new design that meets the stringent criteria. This paper
describes the challenges we faced, and the design solutions that we
presented in the Cochlear Baha BP100.
DURABILITY & PERFORMANCE
Baha users and professionals clearly stated that the reliability of
the processor was important to them. One of the main causes of
malfunction in conventional bone conduction sound processors
is exposure to moisture and dust that causes breakdown of the
transducer, microphones or electrical components. A device should
withstand exposure to high humidity, dirt, brief exposure to rain
or water spill. Despite such exposure the device must function
consistently.
The challenge of creating system reliability is that a sound
processor must allow air flow to reach the batteries and sound waves
to reach the microphones. This open system needs to be maintained
as well as reconsidered and redesigned to deliver a tight seal without
compromise to the performance goals.
Dual layer protection
In order to limit the risk of processor breakdown after exposure
to diverse environmental conditions, the BP100 features various
protection systems against leakage of moisture, dust and dirt. A
tight seal protects the transducer from moisture entering from the
snap coupling. An integrated TPE seal, produced using 2K moulding
technology, lines the inside of the battery door and a GORE-TEX ®
membrane protects the microphone ports. A unique battery hatch
effectively inhibits water and dust from penetrating into the internal
parts, which means that the BP100 functions even after use in rainy
weather or after accidental exposure to water.
The resulting dual layer protection system (Figure 1) differs from
the traditional battery door design to achieve a superior level of
moisture resistance without interfering with the performance ability
of its microphones. In addition, the user can simply replace the sliding
battery door with a new one, without the need for any special tools.
These sliding battery doors are available in a variety of colours (even a
child-friendly range).
Internal battery hatch
Integrated TPE seal
GORE-TEX ® membrane
Figure 1. The dual layer protection system of the BP100

Moisture resistant
To evaluate moisture resistance, we subjected the BP100 to rigorous
testing (Figure 2). A splash test was conducted by exposing sound
processors to water sprayed from different directions at a rate of three
litres per minute. The results were conclusive. None of the tested sound
processors showed any signs of leakage of water into the battery cavity,
nor was any water found inside the shell. All processors functioned
correctly and showed no degradation of performance. In practice, this
means that the BP100 could be worn if a child was to inadvertently
run through a sprinkler or spend a short period of time in the rain. The
overall design innovations preventing water from entering the sound
processor makes the BP100 moisture resistant.
Figure 2. Splash testing of the BP100
Wind noise protection
The BP100 is acoustically transparent and allows sound waves to pass
through to the microphones without distortion. The wind-resistant
quality of the GORE-TEX ® membrane has significantly improved
performance in wind noise compared to the Baha Divino ® . To measure
the processor’s performance in wind, we took it to the wind testing
facility at Chalmers University of Technology in Gothenburg, Sweden
(Figure 3). The geometry of the battery door and the GORE-TEX ®
membrane was found to have a very positive effect on reducing wind
noise, providing a reduction of approximately 5dB compared with the
Baha Divino.
Figure 3. Wind tunnel at Chalmers University of Technology
Transducer stability
We identified transducer failure as one of the most important factors
impacting processor reliability. At the core of the Baha sound processor,
the transducer creates the vibrations that transfer sound through the
skull bone to the inner ear. It is a very precise component with the air
gap inside the vibrator measuring roughly the width of a hair (50-70
micrometres). The allowed tolerance of the mechanical components
are smaller still, at only a few micrometres they are less than 1/10 the
width of a hair. As such, the transducer is sensitive to excessive force
that could result in its collapse.
To ensure a functioning sound processor the BP100 transducer
was redesigned to improve stability. We reengineered the transducer
suspension and integrated new mechanical stops in the snap coupling.
The changes prevent excessive movement in either direction thus
protecting the transducer and reducing the risk for collapse (Figure 4).
The BP100 also utilises the latest surface technology, with a diamond
embedded alloy washer used in the vibrator that increases friction and
stability.
Figure 4. The transducer suspension and mechanical stops
Titanium foundation
The BP100 is built on a strong titanium foundation that protects
it against damage. Not only is titanium a light weight, strong and
stable material perfect for platform manufacturing, it has the unique
properties of being human-friendly and sympathetic to the skin,
making it a standard material for medical implants. We use the latest
Metal Injection Molding (MIM) technology that allows us to create the
unique shape and tolerances required in the BP100 design.
We put the BP100 through a series of tests to prove that the new processor
would provide reliable hearing performance despite repeated exposure to rough
treatment. In total we used 18 different reliability tests: temperature cycling,
damp heat, low temperature, high temperature, temperature shock, atmospheric
pressure, drop (Figure 5), vibration, ingress of water, sweat and humidity, EMC
compatibility, ESD immunity, volume control function, switch on/off function,
program change function, snap function, battery change cycles and connector
system. The results showed that the BP100 stands up well to use, even in challenging
environments.
Figure 5. Drop rig top and drop rig bottom.
USABILITY & FUNCTIONALITY
Tactile buttons
To get the best performance out of an advanced sound processor like
the BP100, the user must be able to make controlled adjustments to
its settings. We designed our tactile buttons to allow precise changes
in volume and program settings. The auditory and visual indicators
confirm changes in program settings so that the user and professional
are always fully aware of the processor settings. While fine tuning of
the device can be performed using the Cochlear Baha Fitting Software,
the creation of the tactile button interface allows professionals to make
adjustments to the device without using a computer.
In addition, the tactile buttons are integrated into the moisture
resistant design. To keep water and dust out of the processor they are
constructed from a composite material that is fully integrated with the
housing. Traditional devices use a rotary volume control wheel, where
experience has shown that these wheels catch dirt and debris and may
be a contributing factor in processor breakdown.
One device for use on both sides
In undertaking our comprehensive study we not only considered the
needs of our users but we also engaged with hearing care professionals.
The design goals of the BP100 were to maximise the usability from
the professional’s perspective. Conventional bone conduction sound
processors are asymmetrical devices. With the introduction of a
symmetrical BP100 (can be used on both the left and right side of the
head) we aimed to streamline logistics to bring down real costs for
clinics by reducing stock requirements and by increasing the flexibility
for hearing care professionals when treating patients.
Universal accessories
The design of the BP100 includes a Europlug in order to be compatible
with all accessories and mainstream solutions. By combining the
Europlug with the plug for the Cochlear Baha Fitting Software, we
were able to provide multiple functions in the same space. The
Europlug is compatible with industry leading FM systems for classroom
applications and Direct Audio Input (DAI) for phones, MP3 players and
other audio sources.
Secure snap coupling
The Baha snap coupling connects to the inside of the abutment. This
unique design provides a secure connection with the abutment and
ensures optimal transfer of vibrations from the processor to the implant
(Figure 6). Importantly, by connecting to the inside of the abutment, it
reduces the risk of disturbance to the soft tissue. The contact between
sound processor and the skin may be an issue that results in revision
surgery. The design of the BP100 eliminates the risk of abutment to skin
contact in normal use.
Figure 6. The snap coupling and abutment
Parental confidence
Children are an important group of users for the BP100 whose needs
(along with the needs of parents and caregivers) dictate specific
design requirements. Parents, teachers and caregivers want a simple
way to monitor the status and settings of the processor. As a safety
requirement, tamper-proof functions are a must. To facilitate
monitoring the functionality of the device, we engineered LEDs that
clearly show if the device is on or off, for which side (left or right) the
device is programmed, the status of the battery, the listening settings
and more. We use advanced automated laser engraving technology to
allow the LEDs to be visible through the protective colour lacquering
of the front lid (Figure 7). In addition, there are audible indicators
built into the device to let parents know that the sound processor is
functioning correctly and the child is hearing with the device.
Figure 7. Light Emitting Diods (LED) on the BP100

Additional safety measures
Additional safety features reinforce the paediatric focus of the design.
A keylock function is enabled by pressing a combination of the tactile
buttons, which means that a child cannot inadvertently change the
settings of the device. Using an optional tamper-proof battery door,
which contains a small lock that requires a tool to open, prevents a
child from accidentally opening the sound processor or exposing the
battery. An additional secure line can be attached to the bottom of the
BP100 to prevent the device from being damaged or lost should it fall
from a child’s Baha Softband or be knocked off the implant.
SUMMARY
Based on test results, and already with more than 5,000 users
worldwide, the BP100 meets the design objectives of the third
generation of Baha sound processors. By undertaking a comprehensive
international study we have identified the needs of Baha users and
Baha professionals. They want performance, and we created a sound
processor that truly sets a new benchmark in hearing performance.
They want industry leading usability and functionality in a reliable
shell. We revised every component of the Baha sound processor to
introduce a design that was innovative, with countless new features and
improvements as described in this paper. The BP100 is both a userfriendly
and flexible solution and leads the way in the bone conduction
hearing industry.
Manufacturer:
Cochlear Bone Anchored Solutions AB Konstruktionsvägen 14, SE-435 33 Mölnlycke, Sweden Tel: +46 31 792 44 00 Fax: +46 31 792 46 95
Regional offices:
Cochlear Americas 13059 E. Peakview Avenue, Centennial, CO 80111, USA Tel: +1 303 790 9010 Fax: +1 303 792 9025
Cochlear AG European Headquarters, Peter Merian-Weg 4, CH-4052 Basel, Switzerland Tel: +41 61 205 0404 Fax: +41 61 205 0405
Cochlear Ltd (ABN 96 002 618 073) 14 Mars Road, Lane Cove NSW 2066, Australia Tel: +61 2 9428 6555 Fax: +61 2 9428 6352
www.cochlear.com
GORE-TEX is a registered trademark of W.L. Gore & Associates.
Baha and Baha Divino are registered trademarks, and Baha Intenso is a trademark of Cochlear Bone Anchored Solutions AB.
Cochlear and the elliptical logo are trademarks of Cochlear Limited.
© 2010 Cochlear Bone Anchored Solutions.JUL10. Printed in Sweden. E81839A
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