- The Report for Forefront of Rion Technologies
- Waterproof and water repellent technologies for hearing instruments
- Waterproof technology for hearing instruments – Innovative Technology
Technology 1: Development of waterproof acoustic film
The first subject to be solved was to develop the special film with passing the sound clearly but filtering water and sweat. Rion tried to examine many kinds of material for such purpose to keep the good acoustic performance (sound pressure level : within 3dB loss) and to stand up to the water pressure at a depth of 1meter.
As the result, porous film, which was used for the space suits, was selected and the severe conditions could be overcome with the development of manufacturing technology of porous film with max. 10μm diameter.
Diagram of the waterproof acoustic film
Acoustic characteristics of the waterproof acoustic film
Technology 2: Development of waterproof structure
Another subject to be solved was the development of waterproof structure special to hearing instruments, different from other electronic devices. As hearing instruments have been using the materials of plastics/resins, it was needed to design simply for waterproof and to make the pressure to the packing lower, compared with metal structure (for example, watch etc) which is available to keep the pressure to the packing higher.
On the other hand, the availabilities to wide frequency range was required for acoustic performance. Rion hearing instruments could solve such subjects and became one of the basic structures of hearing instruments.
The construction of waterproof hearing instrument HB-35PT
Technology 3: To use air batteries with waterproof hearing instruments.
Because of the demands to mercury-free batteries as to measure for environmental pollution, air batteries have generally been used for hearing instruments. But the air batteries need to contact with the air, so it was a big problem to keep waterproof and to supply the air for waterproof hearing instruments. Rion could solve this subject to develop the waterproof film with the performance of passing more than 5ml/hour and with keeping strength, and introduced the new waterproof hearing instrument for using air batteries in 1994.
The first waterproof hearing instrument in the world to be used with air battery: HB-54
Technology 4: To make custom designed hearing instruments waterproof
After it was succeeded with BTE type hearing instruments, the next subject for Rion was to make the ITE (In-the-ear) type custom designed hearing instruments waterproof. For this ITE type, it was important to make waterproof not only for the microphone side but also for receiver side. Because higher sound pressure must be required in receiver side than microphone side, it was extremely difficult to develop the waterproof film to pass the sound with avoiding any sound pressure loss and without affecting to sound quality. Finally it was solved with thinking from another angle, the film transmitting vibration instead of the film making sound passed, and Rion could succeed in developing the waterproof ITE custom designed hearing instruments.
Another advantage of this hearing instruments is to wash them because the waterproof film is set in receiver side. The users can wash sweat and earwax from them and it makes comfortable wearing with clear condition for the users.
ITE (in-the-ear) type waterproof custom designed hearing instrument: HI-G4WU
Technology 5: To make hearing instruments for severe hearing loss waterproof
Rion succeeded in developing waterproof hearing instruments for the users with severe hearing loss. It could conform to IP65/68 for waterproof and dust-proof and have enough performance with high power to be suitable for the users with higher and severe hearing loss but small size. Further this hearing instruments are featured with a variety of digital functions.
*IP65/IP68 corresponds to JIS C 0920 : 2003/IEC 60592 regarding standards on the external housing of electronic equipment and devices.
BTE (Behind-the-ear) type waterproof hearing instrument: HB-W1RA