Hearability Limited

About Hearing Instruments

What is a Hearing Instrument

A hearing instrument is a miniature sound amplifier. But if it only amplified sound, its use would be very limited. Each hearing loss is unique to the individual. Some people have hearing loss in the high frequencies. Others have hearing losses in the middle to low frequencies. Each person also has variable comfort levels when it comes to the loudness of sound. Thus, a hearing instrument must be highly selective in how it amplifies sound.

Advanced hearing instruments use programmable technology. Hearing test results are entered into a computer and hearing healthcare professionals then use specialised software, to adjust the hearing instrument to the patient's individual needs. These hearing instruments are often called “analogue programmable” or “digitally programmable” devices.

Traditionally the NHS has provided analogue hearing instruments for children and adults alike. With the emergence of digital hearing instruments, the NHS had to make a choice of which type of technology to supply. For the most part, the NHS continued to issue analogue hearing instruments supplemented by digital hearing instruments if they would benefit a patient. In the 1990's digital hearing instruments became more widely available particularly for children, but this left many adults unable to get them on the NHS. Currently Digital hearing instruments are available to all via the NHS however the waiting times are growing with a typical waiting time being in excess of 2 years. Private hearing instruments can be fitted within 2 weeks in most cases.

So how do analogue and digital hearing instruments differ?

There is often nothing on the outside of a hearing instrument that will give you any clue to what type it is, but inside it is a different world.

Digital hearing instruments have a miniature computer chip inside them that has its own memory and essentially controls them. This chip is able to monitor the sounds coming into the hearing instrument and adjust them according to a pre-determined set of instructions. These instructions are known as the ‘programme’ and that is why digital aids are referred to as ‘digital programmable’ or ‘digital signal processing’ (DSP) aids.

Analogue hearing instruments are normally adjusted by an audiology technician at the hearing clinic, using a set of miniature screwdrivers. Each control on an analogue instrument has to be manually adjusted until it performs best for the patient.

Digital hearing instruments are ‘programmed’ by being connected to a computer which automatically match the settings on the aid to the requirements of the patients' audiogram. The computer stores the programme for each patient, making reprogramming the hearing instruments or making adjustments a straightforward process.

Digital hearing instruments are also more sophisticated in how they deal with sound and have automatic functions that are way beyond any analogue hearing instrument. These include multi-programme, feedback cancellation, directional and adaptive directional microphones, adaptive noise suppression/reduction, multi channel compression, automatic programme switching, spectral enhancement and transient enhancement.

More advanced hearing instruments are labelled “fully digital” or simply “digital”. These instruments can be programmed by a computer and contain a microprocessor. Digital hearing aids translate sounds into digital code. This code is processed according to the users needs and converted back into sound. These sound advanced processing capabilities would be impossible without the microprocessor and the digital signal processing.

What hearing instruments cannot do:

• Not water proof - Like any other electrical items, if a hearing instruments comes into contact with water the electrics will become short-circuited.
• Not all instruments can adapt to the room you are in and cut out unwanted echo's/background speech babble. Many instruments have trouble recognising speech, especially if there are a number of conversations, unless they include noise tracker technology, which eliminates background noise, so one can focus on your conversation.
• Wind rush - In an open top car, when riding a bike or playing sports, hearing aids can be uncomfortable, unless they feature technology to help reduce wind noise.

Types of Hearing Instruments

Studies have shown that the brain takes time to “re-learn to hear” with a hearing instrument. The hearing impaired person has to get used to a number of sounds they have not heard for a long time and perhaps even forgotten. Modern hearing instruments are highly advanced and can tailor amplification to each user's needs. The full range of models is as follows:

Completely-In-The-Canal (CIC)

This is currently the smallest custom-made hearing instrument. The shell is designed to fit deep inside the ear canal and be practically invisible. Often, these devices are limited in the number of programs and options. They are most appropriate for mild to moderate hearing losses.

In-the-Canal (ITC)

This hearing instrument is custom-made to fit your ear. It is slightly larger than the CIC. This style provides access to multiple listening programs and is appropriate for mild to moderate hearing losses.

Half Shell (HS)

The Half Shell is custom-made to fit the ear and is slightly larger than the ITC. It will usually provide access to telecoil and multiple listening programs. The Half Shell is typically for hearing losses ranging from mild to moderately-severe.

Full Shell (ITE)

This style is also custom-made and fills your outer ear or Concha. A full shell ITE provides access to telecoil and multiple listening programs. It is typically for hearing losses ranging from mild to moderately-severe.

Behind-the-Ear (BTE)

This style fits behind the ear and comes in a variety of sizes. It is attached to an earpiece, or ear mould, that can be custom-made for the ear or be placed into the ear canal itself.
BTE instruments fit a wide range of hearing losses - from mild to profound. BTE devices also may have Direct Audio Input capabilities - please see below.

Hearing instrument technology

Automatic Signal Processing

Hearing instruments monitor the environment and automatically adjust volume to make speech audible and reduce background noise. Soft sounds are amplified and loud sounds receive little or no amplification. This type of signal processing keeps the output of the hearing instrument comfortable, so manual changes using a volume control are unnecessary.

Data logging

Data logging constantly monitors listening situations and wearing patterns. It stores the information and provides valuable insights for more efficient troubleshooting. The Data Logging feature in some instruments can record the most recent 100 hours of patient usage. It can record when and where the hearing instruments is used, how often, for how long and what programmes have been used. It can even tell you how often the volume control is used and in what situations. The information can be viewed clearly and simply in graphical formats using the required software. It provides objective information regarding patient's lifestyles and their listening demands and is invaluable in the rehabilitation process.

Fixed & Adaptive directional microphones

Adaptive directionality is one of the most important factors in improving speech intelligibility in the presence of background noise. With sophisticated multiple microphones, one at the front and one at the back of the hearing instrument, the microphones can adapt to the situation. They do this by zooming in and focusing on the speech arriving from the front of the ear and at the same time reducing the sounds that arrive from the opposite direction.

It can maximise the signal-to-noise ratio in all types of noise, including time-delayed noise reflections and wind noise. The benefit of this is better speech understanding in any type of noise environment.

Direct Audio Input

Direct Audio Input allows a hearing instrument to communicate with assistive listening devices. It is often used in classrooms, auditoriums and places of worship to enhance the listening experience. Direct Audio Input is typically available on BTE hearing instruments for people with a moderate to sever hearing loss. When used in some hearing instruments, it's proven to improve speech understanding in noise.

Targeted noise reduction

The inability to hear in a noisy environment is a common complaint among hearing instrument users. Background noise in a restaurant is an example. Modern hearing instruments use sophisticated computer programs that continually monitor the incoming signal and determine the amount of noise in the environment. The hearing instrument automatically minimises background noise in the appropriate frequency regions based on the instructions received from the microprocessor. This allows the user to listen to speech more comfortably in noisy environments.

As hearing instruments become smaller and microphones are positioned together, this source of internal noise becomes louder. Noise reduction combined with low-level expansion is designed to distinguish speech from noise. Low level expansion is used to eliminate the sound the processor makes itself and reduce microphone noise in quiet environments.

It also identifies low frequency sounds such as the hum from a fridge or an air conditioning unit and reduces their amplification.

Processing speed

This ensures that hearing aid wearers will not experience any echoing effect when processed sound lags behind “real” sound coming through open vents - 3 - 8 MS.

Feedback management

Feedback is the unwanted whistling or buzzing noise that a hearing aid can make. Feedback management technology allows hearing instrument user's access to increased high frequency amplification without feedback. High frequency information carries the sounds of speech responsible for clarity. In less sophisticated devices feedback can be reduced by turning down the volume. This method of controlling feedback often sacrifices the clarity of speech. Modern feedback cancellation methods continually monitor the incoming signal and adjust the hearing instrument to minimise feedback without reducing gain - inverted signal.

Automatic - Self adjusting

We call this SoftSwitching™ and it links into Real-world Directionality. It allows digital hearing aids to monitor and adapt to changes in the users environment, reducing background noise without any effects of speech and takes place automatically without you noticing.

When the user is sat listening to the latest family news, amid the noise and excitement, they'll be completely unaware of the digital activity taking place in their ear. All they'll experience is the pleasure of knowing they can easily take part in the conversation.

Open fitting

There are a broad range of open fittings that are designed to help reduce the common user frustration. *35% of hearing aid wearers refer to occlusion (when air becomes trapped in the ear canal) as a source of dissatisfaction with their hearing instruments. Dispensers need to determine whether their patients hearing loss falls within the open-fitting range. Options for open fitting could be a Flex-tube, Tulip-Dome, Open Vent and StepVent, which are discreet in appearance, comfortable and have minimal occlusion.

Warp Technology

Warp is basically the technology behind Noise Tracker and is the fastest processor in the industry, Warp allows Noise Tracker to measure, define and clarify what you hear every millisecond - and that means clear speech and superior sound quality.

The benefits are that it minimizes background noise so you can focus, even in a sea of conversations. Warp technology delivers benchmark sound quality, so constant noises such as air conditioners or PC fans are no longer a problem. This means that the hearing aid user does not need to strain to hear and understand, allowing the user to feel less tired at the end of the day.

To arrange a free hearing examination call our Care Centre on 01903 237732