WidexLink offers new possibilities for transmission of sound from assistive listening devices (e.g., DEX devices) to hearing aids, and exchange of synchronisation data between hearing aids.
The new digital transmission technology is central in our new wireless hearing aid series, WIDEX DREAM and WIDEX SUPER. It is used for the transmission of both data and audio signals in a large number of situations.
Stream sound from external devices
WidexLink is used for the transmission of sound from external devices to the hearing aids when the user watches TV, talks on his mobile phone, or listens to music.
The technology is also used for the transmission of data between the remote control (RC-DEX) and hearing aid, and in the exchange of synchronisation data between hearing aids (InterEar communication).
We are convinced that wireless technology is the future in the hearing aid industry. However, the success of any given wireless transmission technology will depend on at least three key issues when applied to hearing aids: Sound quality, transmission robustness, and power consumption.
It is no simple matter to design a system that is able to maintain high audio quality, low battery drain, and robustness against transmission errors at the same time.
In order to achieve these goals, several key components of the wireless system have been carefully designed.
The Audibilty Extender has been tested with adults as well as children by Widex research facilities, including ORCA US. We have positive results from these clinical trials suggesting that the linear frequency transposition facilitates better speech intelligibility and access to environmental sounds.
First, a fast and efficient audio codec (short for encoding/decoding) and a new accurate and sensitive digital radio receiver system have been developed to ensure fast, stable, and trouble-free transmission of sound and data. It was a requirement that the digital audio codec should be based on a coding principle that would ensure that the signal is perceived as close to the original sound as possible.
Another factor in maintaining a high sound quality is a low audio delay over the wireless transmission system. The digital coding system has been designed in such a way that no data need to be re-transmitted and slow down the transfer of the audio signal as a result.
In fact, WidexLink is able to offer an unparalleled low delay of <10 ms when transmitting sound. This ensures minimum distortion and echo-free sound quality when direct sound in the room is mixed with transmitted sound.
Audio bandwidth is also important for high sound quality. Thanks to the WidexLink technology, we are able to offer an industry-leading audio bandwidth of 100 Hz to 11.2 kHz for transmitted sound in models with a ClearBand receiver.
Ensuring battery efficiency has also been a major concern in the design of WidexLink. This has been achieved by means of efficient data compression methods, and the invention of the new patent- pending, highly sensitive radio receiver that permits low transmission power.
Robustness has been achieved in multiple ways. In addition to the robustness of the audio codec and the radio receiver mentioned above, robustness has also been achieved by means of the channel coding technology that detects and handles errors quickly and securely.
The need for a new technology
Today, Bluetooth is probably the most popular wireless technology for transferring data and digital sound. However, Bluetooth is designed for the mobile telephone industry and has some drawbacks which create serious problems in hearing aids.
First and foremost, Bluetooth is an extremely energy-demanding technology. The Bluetooth chip uses so much power that it has no practical application in the hearing aid industry.
The consequences of delay
Another serious drawback is that standard Bluetooth has a high built-in delay of 150 ms when audio is transmitted through the Bluetooth codec. That is, transmitted sound will reach the ear 150 ms later than the direct sound in the room. The result is an extremely disturbing echo effect. Furthermore, the delay is so large that the picture appears unsynchronised with the sound.
The Psycho-acoustic artefacts due to latency (delay) between direct sound and transmitted sound:
150 ms delay: Severe echo effect. Audio and TV picture are not in sync
30-40 ms delay: Clear echo effects start to occur
10-30 ms delay: Sharp metallic sound due to comb filter effect
0-10 ms delay: Transparent sound
The unparalleled low delay of <10 ms offered by the WidexLink technology ensures minimum distortion and echo-free sound quality.