BRUEL & KJAERS PULSE
HELPS HEARING AID DESIGN.
Widex, a pioneer in the hearing aid industry and one of the
worlds leading producers of high-quality hearing instruments,
is a Danish company established in 1956 by Christian Tøpholm
and Erik Westermann. Still family-owned, the companys hearing
instruments are marketed and distributed through an international
network of distributors in 80 countries. Some 97 percent of
Widexs production is exported.
The relationship between Widex and Bruel & Kjær started 39 years ago,
so Widexs search for a new measurement platform to replace the
legendary Type 2012 naturally included Bruel & Kjær. The new
instrumentation would not only have to accommodate Widexs current
needs but also represent a secure investment for the future.
The challenges of hearing aid design
The ultimate goal for hearing aid designers at Widex is to give users the
same opportunities for communication as people with normal hearing.
Hearing aid designers take into consideration a long list of expectations,
and corresponding challenges such as improving speech intelligibility in
noise, reproducing Natures sounds, ensuring that soft sounds are audible
and loud sounds are never uncomfortably loud, effecting optimum music
reproduction, and improving the users perception of his or her own voice.
Although no hearing aid can restore normal hearing, recent advances in
digital electronics, acoustics and audiological science have combined to
make todays instruments of greater help than ever before. Widex believe
it has the products and technology to help the hard of hearing to get the
most out of everyday situations.
Keeping it in-house
Widex is a self-sufficient company, doing all of its research and development,
testing, design and production in-house. This knowledge-based company
is at the cutting edge of innovation within hearing aid technology, earmarking
considerable resources for audiological and technological research to yield
state-of-the-art, reliable hearing instruments. Like Brüel & Kjær, Widex has
been in the business of innovation from the beginning. For example, it
developed QUATTRO, the first hearing system making use of remote control,
and Senso, the first fully digital in-the-ear hearing aid, up to the award-winning
Senso CIC (completely-in-canal) model.
When a company of Widexs calibre decides that its current acoustic
measurement platform can no longer fulfil its technical requirements, huge
effort is put into an intense investigation of all possible solutions on the market.
Only the best is good enough.
Open and flexible solution required
Widexs main requirement was a solution able to make the traditional standardised
electroacoustic measurements performed on hearing aids. For many years,
Widex has successfully made these measurements using the Type 2012 with
its own dedicated software. However, a technology-driven company such as
Widex also required a solution that was open and flexible enough to perform
measurements not previously possible with the Type 2012. And measurements
such as noise floor, directivity, EMC immunity, etcetera, were also considered
to be important.
Introducing the PULSE platform
Brüel & Kjær presented a solution fulfilling the essential requirements, and
introduced the PULSE platform to technicians, engineers and management at
Widex. It is easy to imagine how attractive the PULSE platform must have
appeared to a customer familiar with the user interface of the Type 2012.
However, Widexs Measuring Engineer R&D, Søren Christensen, responsible
for finding the replacement, was initially cautious.
Shortly after the introductory meeting, Widex engineers attended two days
of PULSE training at Bruel & Kjaer University in Denmark, with Bruel & Kjaer
engineers on hand to provide all the support needed. The primary objective
of this training was to ascertain to what extent a standard PULSE system
could replace the Type 2012. PULSE SSR Analysis Software Type 7772
went a long way to satisfying the requirements, leaving only two tasks
outstanding which could easily be resolved with the help of VBA (Visual
Basic® for Applications) programming.
Out with the old, in with the new
Widex is the first customer to use PULSE 9.0, and in the months after delivery
Bruel & Kjaer following its progress closely, helping it to successfully make the
transfer to PULSE.
The measurement system supplied to Widex includes the PULSE Electroacoustic
Test System, PULSE Data Recorder, PULSE Time File Management, and
PULSE Data Manager, 5-user. This set-up allows Widex to make a comprehensive
range of measurements on hearing aids.
Gain and output measurements include output sound pressure level response,
full-on acoustic gain, frequency response, the effect on gain with different battery
impedance or voltage settings, and OSPL90 with different battery impedance
or voltage settings. Measurements of amplitude non-linearities include harmonic
distortion with different battery impedance or voltage settings, and intermodulation
distortion with different battery impedance or voltage settings. Measurements of
internal noise generated are determined by 1/3-octave analysis. Induction pick-up
coil measurements include frequency response and harmonic distortion.
Automatic gain control measurements include input/output characteristics for
sinusoidal signals and dynamic output characteristics for speech signals at
Special Test Mode measurements include the effect of band gain control on the
basic frequency control, group delay, and phase and amplitude characteristics.
Real Mode measurements include input/output characteristics at different bands
and filter settings, attack and release time, oscillator frequency sensitivity and
range, and absolute gain level check microphone noise squelch at different bands.
The future for Widex looks bright indeed. With untiring commitment to R&D,
and now with the help of the PULSE platform, Søren Christensen and his colleagues
can only succeed in their quest to break new ground and enhance hearing aid
About Brüel & Kjær
With more than 60 years experience, Brüel & Kjær is a world
leading manufacturer and supplier of sound and vibration
solutions for use in a wide range of applications including
environmental noise measurements, building acoustics,
vibration measurements and quality control for use in the
automotive, aerospace and consumer industries, as well
as by local authorities.
For more information, please contact :-
Bruel & Kjaer UK Ltd.
Bedford House, Rutherford, Close, Stevenage, Herts. SG1 2ND. UK
Tel: +44(0) 1438 739000
Fax: +44(0) 1438 739099