The performance and functionality of your hearing aid can be enhanced by the inclusion of special device features. These features include telecoils, automatic volume controls, additional listening programs (for music/telephone), directional microphones (fixed and adaptive), remote controls, automatic noise suppression, feedback management or cancellation, wind noise reduction, e2e (ear to ear) transmission, data logging/ learning and the recently introduced open fit behind-the-ear systems.

Telecoils

A telecoil responds to magnetic signals provided through an audio induction loop. Loops can be installed in your home telephone and are often located in theatres, churches and other public venues. The telecoil generally operates with the hearing aid microphone turned off. This means that background noise is not a problem.

Additional listening programs

Some models of hearing aids contain additional listening programs that act to change its tone and, in so doing, can be tailored for specific listening environments. For example, listening to music, or conversation in quiet or competing noise, may be more pleasant or intelligible, depending on the program or tone you select. They are useful for individuals who find themselves in a range of different listening environments.

Directional microphones

The use of directional microphones in hearing aids improves the ability to follow and understand speech in the presence of background noise. They are recommended for individuals who have difficulty hearing speech clearly in noisy environments.

Switchable directional microphones

A push button or switch is operated by the wearer to alternate the hearing device between directional or non directional modes. In the directional mode sounds from the front receive priority over those from behind. In general we face the person to whom we are speaking with the noise at our rear. This provides an advantage in understanding speech more clearly in background noise environments.

Adaptive directional microphones

A new variety of directional microphones have recently become available that are popularly known as “head hunters”. Put simply, these microphones seek out background noise and minimize its intrusion to the listener by electronically tuning its sensitivity to the best advantage.

In particularly advanced instruments the microphones “listen” to their environment and determine the location of and frequency composition of the noise. Having analyzed the noise environment the microphone sensitivity is adapted electronically to reduce noise sources. This can be done for several different noise sources and frequency compositions simultaneously. Equally impressive is the ability for ongoing environmental noise monitoring and the automatic and continuous microphone tuning to give the listener the best possible clarity at all times in a changing environment.

These advanced microphones provide the listener with significant advantages in challenging listening environments.

Wind noise reduction

The advances in microphone technology have enabled unique solutions to be applied to environmental wind noise. For those with active outdoor lives wind noise can be problematic. Advanced systems in some devices can detect the presence of wind noise through environment sound analysis and apply an electronic adjustment to minimize its impact on the wearer. The hearing instrument does this automatically.

e2e Ear to Ear

Introduced in 2004 this technology has been a significant breakthrough. The e2e enable instruments to communicate with each other to ensure both devices are operating optimally to provide the maximum benefit to the wearer.

In particular the benefit of a directional microphone is maximized when the volume of each hearing instrument is equalized. The e2e technology ensures that the volume of each aid is communicated back and forth thus resulting in maximum directional benefit.

As hearing instrument microphones are particularly sophisticated in e2e devices and adapt automatically to their environment it is important they operate in matched configuration. The e2e classifies the noise environment presented to each device then selects the most beneficial combination of microphone parameters for the particular listening situation, automatically. In this way again, the benefit to the wearer in terms of comfort and clarity is maximize automatically and continuously.

Another advantage of the e2e technology is that their owner only requires one hearing aid to have controls. A volume control on one device adequately controls the volume on the other resulting in a smoother faceplate and overall smaller device sizes

Environmental classification

In order to maximise comfort and intelligibility advanced hearing devices attempt to classify the listening environment of the wearer and apply specific settings to the instrument. By examining time delays, loudness and frequency differences arriving at twin microphone ports on board the hearing instrument the acoustic environment can be classified. Usually sound is classified into speech in noise, speech in quiet, wind noise or music. The hearing instrument then applies a number of pre determined electronic strategies to ensure the wearer enjoys maximum comfort or intelligibility in the given situation. The application of specific electronic strategies based upon environmental classification enhances the benefit of the hearing instrument and facilitates data logging and data learning strategies to be applied.

Data logging and data learning

 A number of recent instruments now incorporate data logging. This is a system that classifies the sound environment of the wearer into one of several categories and records the loudness and duration of exposure in the hearing device memory. The information can then be retrieved when the hearing aid is connected to the programming computer and much useful information extracted that enables the practitioner to fine tune the hearing instrument.

Data learning is an extension of data logging in that the hearing instrument applies corrections based on the preferences of the wearer. For example, if the hearing instrument recorded that the wearer always turned the hearing instrument down 5 decibels when in a noisy situation, then the hearing instrument would learn and apply this automatically. Across time the wearer’s preferences continuously update the hearing instrument settings by learning from the wearers manual adjustments. As a consequence, the hearing instrument becomes a perfect fit!

Head related transfer functions

Each person’s outer ear has a unique anatomy that confers an acoustic “footprint”. The subtle acoustic differences arising from the ear anatomy are analogous to the unique acoustics of rooms in your home. When we change the anatomy of the outer ear with a hearing instrument, the wearer initially notices subtle differences in acoustics. Some advanced hearing instruments can measure the unique way sound arriving at the outer ear is transformed in its transmission to the eardrum. Replicating this transformation electronically can assist in the early stages of adapting the hearing instrument usage.

Remote controls

A number of hearing aids have a remote control option that enables the user to access a wider range of hearing aid controls. These may include on/off, volume, tone, telecoil and additional listening programs. They are useful for active individuals and sometimes for those who may have difficulty operating the standard controls on a hearing aid. Their operation can be complex and needs to be carefully considered. They are not available with all types of hearing aids.

Feedback control

This is an electronic system of determining the level at which feedback may occur, by an in situ test, and reducing the power of the hearing aid correspondingly when the parameters are next detected.

This works effectively but may result in less amplified signal reaching the clients ear drum and may reduce clarity very marginally.

Feedback cancellation

This is a more sophisticated method of feedback control, sometimes used in industry and airline cockpits to reduce noise.

It works by the hearing instrument introducing a signal into the pathway in opposition to the feedback in a manner that they cancel each other out. An analogy would be ripples in a pond cancelling one another out as they collide on the waters surface.

This is a very effective technology and usually operates continuously and instantly feedback is detected. For many individuals occasional feedback is not a disturbance but for others the wearing of a hat or reclining on a lounge, or cupping one’s hand to the ear may be sufficient to provoke feedback in the hearing instrument.

A feedback canceller system can substantially eliminate such feedback occurrences.

Automatic noise reduction

A number of advanced hearing instruments have either manually or automatically activated noise reduction facilities.

Each manufacturer has a particular electronic strategy but in general they seek to analyze the acoustics of the listeners’ environment and modify the instruments sound processing to provide the best clarity for speech.

Multiple channels and bands

These sound processing features “slice” up the speech frequencies into Channels and/or narrower bands each of which process its sound input relatively independently of each other.

This has the advantage of enabling the amplification characteristics for an individual to be shaped most closely to their hearing loss. The Channels also assist in reducing noise input in one channel without affecting the others enhancing the clarity of speech for the listener.

Automatic volume controls

This feature adjusts the incoming sound to comfortable levels automatically. It does this by making soft sounds louder and loud sounds softer. The benefit to the wearer is the convenience of rapid and appropriate loudness adjustments and overall greater comfort. The automatic volume control reduces the conspicuousness of reaching to one’s ear to adjust a manual volume control wheel.

Open fit systems

For individuals with good low frequency hearing there can exist an initial awareness of ones own voice whilst speaking with the hearing aid.

In general this awareness dissipates rapidly and for individuals with more than a mild low frequency loss it is non existent. The own voice awareness occurs if the aid is off or on and arises from the vibration of the cartilaginous portion of the ear canal by sounds conducted via the jaw.

Whilst the own voice awareness dissipate quickly for most individuals the initial adjustment can be addressed by the advent of open fit systems. This is available in custom made devices but is most effective in removing own voice awareness in the miniature behind the- ear styles of hearing instrument.

The behind the ear instrument is connected to the ear canal by a very fine diameter capillary tube that renders it near invisible to the naked eye. A small soft dome holds the capillary tube in the canal. The fine structure of the dome renders it acoustically transparent and the own voice awareness is almost eliminated entirely.

The open fit systems are nearly always used in conjunction with feedback cancellation systems which have allowed the emergence of this type of technology into everyday practice.
National Hearing Care is equipped for clients to try this technology ‘on the spot’ via its sets of demonstrator units.