To understand every word

Research News / 1.6.2015

Hearing-impaired people face a challenge at the theater or cinema. Fraunhofer technology promises a remedy integrated into two apps made by Sennheiser Streaming Technologies GmbH. They allow the hearing impaired to adjust the sound to match their individual needs – allowing them to follow the story through their headphones.

© Photo Sennheiser Streaming Technologies GmbH

Now people with hearing loss can adjust the volume with a smartphone app to match their individual hearing ability.

An insanely comical play is on stage, and the audience is roaring with laughter. Yet all too often, guests with limited hearing abilities feel left out – they miss out on just too many details. For this reason, countless hearing impaired prefer the reassuring comforts of the living room chair instead of going to the theater or cinema. The number of affected people is vast: Acccording to recent studies, one out of every six people in Germany is hard-of-hearing, and eligible for hearing aids, and could get them financed through Germany’s health insurance fund. As a matter of fact, however, not even 25 percent of eligible patients take advantage of this option. Because, unlike eyeglasses, many people still see a stigma tied to hearing aids.

Optimizing sound individually

The “Cinema Connect” and “MobileConnect” apps from Sennheiser Streaming Technologies GmbH aim to ensure that soon, the hearing-impaired audience members at a play or a movie are once again able to perceive and understand every single word, even if they are wearing no hearing aid. This assisted hearing technology is the brainchild of the researchers at the Oldenburg-based Project Group Hearing, Speech and Audio Technology of the Fraunhofer Institute for Digital Media Technolgy IDMT.

The basic principle of the Sennheiser technology is for a streaming server to transmit audio signal from the stage or screen directly to the viewer’s smartphone. The phone reproduces the data directly, via the headphones as they are being loaded through the secured network. Alternatively, if the viewer wears a hearing aid adapted to his or her smartphone, the app is also able to send the sound signal to the hearing aid directly via Bluetooth instead. “Our technology, which is integrated into the apps, does not just enhance the sound volume, rather it lets the theater attendee individually adjust the sound,” affirms Dr. Jan Rennies, Head of group at IDMT. Because the range of optimal sound adjustments is narrow: loud noises swiftly appear to be too loud, and therefore have to be reduced. By contrast, soft speech components require substantially greater amplification. And depending on the type of hearing loss, the affected individual is unable to perceive each frequency with equal intensity: many people can still detect lower sounds quite well, but when sound reaches a higher pitch, it gets difficult.

When engineering the individually adaptable hearing support, the challenge was primarily in designing intuitive functionality. Ideally, each person should be able to improve the sound at any time autonomously – without having to consult an acoustics expert, as is the case with hearing aids. That is precisely what these apps accomplish: by driving with a finger across the touchscreen of his or her smartphone, the user “guides” a small dot across the screen. Volume rises or falls by drawing the dot upward or downward. Shifting the tone horizontally makes the sound softer to deeper.

Integrated into current Sennheiser apps

The integration of the “Personal Hearing” function into two apps offered by Sennheiser is scheduled to arrive this summer, and at no charge. Users can go to the “Culture Inclusive” culture portal ( to find out which cinemas and theaters offer the technology.

Fraunhofer’s assisted hearing function is also being used in other applications; IDMT scientists are currently developing another app that turns an iPhone into a microphone, and features customized amplification. At the beginning of this year, Sennheiser electronic GmbH & Co. KG unveiled its cordless headphones, featuring customized sound adjustment from Fraunhofer. Another area of research and application is hearing assisted telephony. “Our user studies indicated that the technology for the hearing-impaired is immensely helpful in various applications scenarios, such as headphones or telephones, and frequently those with normal hearing also consider it beneficial,” says Dr. Jens Appell, division head  of the Hearing, Speech, and Audio Technology project group. “So far, the majority of test subjects are enthusiastic – whether they had a hearing aid or not.”