Hearing Aid Technology

Not Your Father's Hearing Aid

A broad range of technology and a whole host of features are available in each hearing aid style. The cost of hearing aids generally depends on the technology and the number of features the instrument has, and not necessarily on the style selected.

Basic technology

Basic digital hearing aids generally require the wearer to make some manual adjustments in certain listening situations – such as turning a volume control up or down, or pushing a button on the aids in order to reduce noise coming from behind. The processor may separate incoming signals into two or more channels and process each channel separately. For example, a basic two-channel instrument may give more amplification for high frequency versus low frequency sounds if required based on the hearing test results. By contrast, premium technology hearing aids may have 16 channels or more, and therefore offer a higher resolution of signal processing. Basic hearing aids may be computer programmable, but may have fewer or more limited adjustments available for fine tuning and customization as compared to advanced technology. Today’s basic digital hearing aids offer the benefits of better hearing to many people with hearing loss.

Advanced technology

In addition to basic digital hearing aid technology, each major hearing aid manufacturer offers several levels of advanced technology. As the level of technology increases, hearing instruments become more automatic, and are equipped with more sophisticated features for people who regularly encounter dynamic listening situations. Examples of of some of these advanced features, what they do and how they can benefit are shown below.

Directional Microphone Systems - Gives preference to sounds coming from the front of the wearer, and reduces sound coming from other directions. Proven to improve speech understanding in background noise, when the wearer can position himself/herself to face the person speaking, with his/her back to the noise, such as parties, restaurants, etc. Basic systems may require the wearer to push a button to activate. Advanced systems work automatically and can reduce multiple moving noises simultaneously. Satisfaction is higher for hearing aids with directional microphone systems, than for hearing aids without (Kochkin, 2002).

Digital Noise Reduction (DNR) - Determines if signal contains unwanted noise and reduces level of noise if present. The background noise is less annoying and listening comfort is increased. Research supports the use of DNR when it comes to wearer preference and effectiveness (Burton, Smaka, Powers, 2006).

Impulse Noise Reduction - Smooths quick impulse noises such car keys rattling, typing on a keyboard, and dishes rattling. Designed to improve listening comfort.

Wind Noise Reduction - Reduces the whooshing noise of wind blowing across the hearing aid microphone(s). Designed to improve listening comfort for people who spend time outdoors - golfers, boaters, walkers, etc.

Feedback Management - Reduces or eliminates whistling that can sometimes occur. Designed to improve comfort from annoying whistling. Basic feedback systems may cut amplification in attempt to get rid of whistling. Advanced systems reduce or eliminate it electronically, with no or little effect on the overall hearing aid amplification.

Telecoil / Autotelecoil - Picks up signal from a compatible telephone. Wearers can listen to telephone without feedback (whistling). Standard telecoil requires wearer to activate with a switch or button; autotelecoils activate automatically. Telecoils may also be used in public facilities utilizing a "loop" amplification system and with other assistive listening devices.

Bluetooth Interface - Enables hearing aids to wirelessly connect to cell phone or other Bluetooth devices. Designed for better use with cell phones without distortion or interference; enables audio streaming from other devices such as MP3 players, computers, etc.

Data Logging - Stores data in the hearing aids about the listening environments and adjustments made while worn. Data can be viewed by hearing care professional and used for more precise and objective fine tuning.

Learning / Training - Hearing aids learn based on changes made by the wearer, such as to the volume, and then automatically make these changes. More precise personalization of the instruments for a more accurate, individual fitting.

Burton, P., Smaka C., Powers, T. (2006). Digital Noise Reduction: Yes, There is Research Proving Its Effectiveness. Hearing Review, 13(3), 82-87.

Kochkin, S. (2002). MarkeTrak VI: 10-Year Customer Satisfaction Trends in the US Hearing Instrument Market. Hearing Review, 9(10), 14-25, 46.

Technology in Action

Image courtesy of Micro-Tech

What are the real-world benefits of all these features? Imagine you’re in a typical busy restaurant, having dinner with friends. Sounds are coming at you from all directions – dishes clanging, people at other tables talking and laughing, waiters rushing about. You’re wearing your advanced hearing aids, and listening to your friend across the table tell a joke. Your hearing aids are simultaneously reducing impulse noises like silverware clacking on a plate (feature = Impulse Noise Reduction), reducing the whir of the ventilation system overhead (feature = DNR), suppressing the voices of the people at the tables behind you (feature = Directional Microphone System), and storing information about the listening environment to be saved for later fine tuning (feature = Data logging). They’re doing all this automatically while amplifying your friend’s voice, while you relax and enjoy the punch line. These are just a few of the possibilities with today’s hearing aid technology.