man with cochlear implant

Assistive Listening Devices

Cochlear Implants

Cochlear implants benefit persons born with severe to profound hearing loss or do not receive benefits from hearing aids. Cochlear implants have an external portion that sits behind the ear.  There is a second portion (receiver) that is surgically placed under the skin. A microphone picks up the environmental sounds while the external speech processor selects and arranges those sounds which are then transmitted to the internal receiver.  The receiver converts the signals into electric impulses which are then sent to the auditory nerve.  Here is a great explanation with pictures. Normal hearing is not restored, but a cochlear implant can help a person understand speech.  

Hearing Aids
Traditional hearing aids are not discussed in this section because they are very specialized. These hearing aids must be prescribed by an audiologist and custom made for each individual. However, be conscious of the new, revolutionary digital types reported to be very effective — especially for persons with high-end hearing loss. Digital sound has distinct advantages over analog sound, not just in hearing aids, but also in music production because digitizing sound can be very precise in controlling tonal quality and in blocking out background noise.

Digital Hearing Aids

Digital refers to Digital Audio Processing (DAP). A hearing instrument that is truly digital converts an analog sound wave into digital code, a series of 0s and 1s. Specific sections of coded or digitized sound can then be isolated and processed or amplified based upon the specific hearing loss and listening preferences of the user. In addition, a truly digital hearing instrument does not add noise to the signal as it passes through the electronic circuit. A DAP hearing instrument is virtually distortion free. "Digital" is often confused with a "computer" hearing instrument. The latter always refers to the way the controls of the hearing instrument are set using a computer or programming box. This has nothing to do with the way the sound signal is processed which distinguishes a true digital hearing instrument.

Digital hearing aids aren't superior because they're digital but because of the enhanced features available. See this article from the American Speech-Language-Hearing Association for an explanation of the features that digital hearing aids provide.

See the resources section below for two companies that carry digital hearing instruments. (There are many.) 


Super Voice Recognition
Two biomedical engineers at the University of Southern California, Theodore Berger and Jim-Shih Liaw, have designed a type of voice recognition device that is capable of listening better than any set of human ears. It is a neural network that actually mimics the way the brain interprets speech—a cybernetics concept. To learn more, click here. 

Hearing aids are worn in all situations, whereas an assistive listening device (ALD) is made to enhance listening through amplification in specific situations—on the telephone, at a theatrical or concert performance, at a lecture, for televisions, etc. In practice, the ability to selectively amplify signal, but not background noise, is the biggest advantage of an assistive listening device. Some are compatible with hearing aids. ALDs also compensate for less than ideal acoustics.


So What's What in ALDs?
There are three different types: FM, infrared, and inductive loop.

Infrared systems transmit sound through light waves to receivers worn by users. They are typically found in courtrooms, movie theaters, and playhouses. They are susceptible to interference from bright light.

FM radio systems transmit radio waves to receivers and work well in classrooms when the speaker (or sound source) moves around a lot. They are susceptible to light and radio interference. Sound field systems, or speakers, are also utilized in similar situations and are helpful to persons with mild or moderate hearing loss. Sound field systems can be used with FM receivers that connect to the ear.

Inductive or audio loop systems transmit through an electromagnetic field and require no receiver if the hearing aid wearer has a telecoil. Receivers can be provided for others. They are susceptible to EMI interference.


Coupling Devices

Coupling devices, such as headsets, earbuds, and neck loops are also helpful. Sometimes you may attend a conference or lecture where a CART System is used (computer assisted real-time transcription). A stenographer types what is being said verbatim and it is converted into English (or another spoken language such as Spanish) and displayed on a monitor or screen. The CART System requires a fast, accurate typist who can summarize. There are various systems that accomplish the transcription, such as C Print and computer assisted note-taking (CAN).



Vendors & Resources

Assistech Special Needs
Assistive products and information for the hearing, vision, and speech impaired.

Assistive Listening Device Systems Inc.
ALDS Inc. manufactures infrared assistive listening devices, telephone and loop testers, and T-switch training aids. Products are developed and tested with the help of hard of hearing people and are distributed worldwide.

Proprietors of a large variety of ALDs

Audiology Awareness Campaign
Information about hearing loss, ALDs, how to locate an audiologist, etc.

Centrum Sound
Infrared, FM, loop systems, personal systems, sound columns, mixers, etc.

Consumer Affairs Hearing Aids Reviews
Compare brands and read reviews of hearing aids before you buy! Features to consider are provided, such as how a hearing aid fits (behind the ear, on the ear, in the ear, etc.), noise reduction (i.e., wind noise manager or directional microphone), feedback reduction, enhancing speech, programming hearing aids, and different types of hearing aids.

Global Assistive Devices, Inc.
International manufacturer-distributors of alerting systems, alarm clocks, bed shakers, TV caller ID, door signalers, and personal amplifiers.

Carries children and adult hearing devices.

Sound Choice Assistive Listening, Inc.
Consultation, design, manufacturing and sales of assistive technologies for the hearing impaired.

Features discreet hearing aids, hearing aids with natural sound and easy to use hearing aids.

Williams Sound
Manufactures high quality personal and professional assistive listening products.  


Note: Infinitec Inc. does not endorse or recommend these products and has no liability for the results of their use. Infinitec Inc. has received no consideration of any type for featuring any product on this Web site. The information offered herein is a summary; it is not comprehensive and should be carefully evaluated by consumers with the assistance of qualified professionals. The intention of Infinitec Inc. is to offer consumers a brief overview of various assistive technology devices and their applications.