People who have trouble hearing tend to withdraw from their friends and social activities. Today's state-of-the-art hearing aid systems can help hearing-impaired people to live a full life again. Siemens scientists are focusing on systems that create a natural hearing experience by means of computing technologies developed through hearing and acoustics research.
Problems with hearing are increasing worldwide. There are around 55 million hearing-impaired individuals in Europe, and the Center for Disease Control and Prevention (CDC) in Atlanta, Georgia (USA) estimates that one out of every four U.S. citizens over 70 has a hearing deficit. What is more, as the average age around the world continues to grow, the number of people with hearing impairments is expected to skyrocket. In general, not much can be done in terms of drugs or surgery to treat hearing problems. Modern hearing aid technology, on the other hand, can compensate for most types of hearing disabilities.
“Today’s hearing aid systems are like extremely compact computers that break up sound waves into various frequency ranges and then reconstruct them into an acoustic pattern that is aligned with the patient’s individual auditory ability,” says Dr. Torsten Niederdränk, an acoustics expert who, in the course of several positions, has shepherded the development of hearing instrument technology at Siemens. Several hundred Siemens employees at the Audiology business unit in Siemens’ Healthcare Sector are developing ever more technically sophisticated and virtually invisible hearing aid systems.
Research and technological advances have always played a key role in the development of hearing aid devices. Back in 1878, company founder Werner von Siemens designed a telephone amplifier for people with hearing problems. Then, around 100 years ago, the company introduced the first hearing aids. The devices consisted of a battery, a microphone, and an earpiece, sometimes elegantly packaged in a small bag or case.
Since then, the units have gotten smaller and smaller. The first behind-the-ear unit was launched in 1959 and was followed in 1966 by the first in-the-ear device. The first digital hearing aid system was introduced in 1997.
Digital signal processing in particular has been a constant source of innovation. In 2004, a team of audiologists, psychoacoustics experts, and chip designers led by Niederdränk achieved a major breakthrough by linking, for the first time ever, two hearing aid units on the left and the right ears via what at the time was the smallest radio system in the world. The two units were designed in a way that enabled them to automatically and simultaneously adjust themselves to new auditory situations. This synchronized system was particularly helpful to people with hearing damage in both ears.
In the years that followed, Siemens built on the knowledge it gained from such synchronized systems to develop numerous new functions that were eventually combined under the heading of BestSound Technology, which now serves as a technical development platform for providing hearing-impaired users with a pleasant and realistic acoustic experience. For example, an active acoustic feedback management system now suppresses annoying peeping sounds at lightning speed, while intelligent filter functions reduce or avoid the “cocktail party effect” (loud background noises that make it difficult to distinguish words).
“Miniaturization of the electric-acoustic components and steadily improving computer performance have enabled us to continuously improve signal processing, even to the point of three-dimensional sound capture and processing,” Niederdränk explains. System developers believe that there is also great potential to be harnessed from chip design improvements for in-the-ear devices carried directly in the auditory canal and for behind-the-ear hearing aids.
Also on the agenda is the further development of binaural hearing aid systems with integrated radio technology. “Our binaural systems have brought us very close to our goal of creating a balanced and pleasant hearing experience,” says Günther Pausch, Director of Siemens Audiology.
Binaural systems work in coordination with the auditory perceptions of both ears because the brain’s hearing center needs this information in order to generate authentic stereophonic sound. Working with specialists from Hörzentrum Oldenburg, an audiology center west of Hamburg, Germany, Siemens is learning how different sounds, tones, and voices coming from different directions are perceived. Differences in time and sound intensity have a big impact on such perceptions, as they allow the brain to precisely localize voices and sounds and filter out other signals. “We’re working very closely with Oldenburg’s “Audiology Valley” community to develop algorithms that can process real-time data from both hearing aids simultaneously, thus creating a three-dimensional, homogeneous hearing experience,” says Niederdränk.
Smart Ears. Many hearing aids use a wireless transceiver to meet ever more demanding requirements. Siemens experts have been able to place such a unit, which is only a few millimeters long, directly onto the hearing aid chip.
Binaural hearing aid systems wirelessly exchange huge amounts of data. The data is continuously used to calculate and fine tune acoustic signals to both ears, thus generating a homogeneous spacial sound experience. The systems carry out sound analyses many thousands of times per second; the results are then exchanged between the two units. High-end devices can automatically differentiate between spoken words and adapt their output accordingly, thus resulting in optimized understanding of speech, as well as sound quality that adapts to every conceivable acoustic situation at lightning speed.
Extensive research activities and even finer chip architectures will continue the 100-year-old success story of Siemens hearing aids. In recognition of their forward-looking development of binaural hearing aid systems and the great utility these have offered to hearing-impaired users, the University of Oldenburg nominated Niederdränk and his partners Prof. Birger Kollmeier and Dr. Volker Hohmann in September 2012 for the German Future Prize awarded by the President of Germany. Back in the labs, Siemens scientists are already testing new hearing aid models and classification algorithms that will further improve selective hearing in noisy environments. “The systems will become more intelligent and their auditory output will become more natural, among other things with the help of an automatic acoustic situation recognition feature,” Niederdränk explains.