CURRENT DEVELOPMENTS IN SPECIALIZED HEARING AIDS

By:

Dania Shoaib Khan

INTRODUCTION

Hearing Aid

Definition

“Hearing aid is an instrument that amplifies sound particularly speech for people with hearing impairment.”

It may be body worn, Behind the Ear, In the Ear, In the Canal or completely in the canal

Current development on specialized hearing are based on the factors that minimize the downsides of these hearing aids

The current developments basically aims to

Provide Smooth sounds and minimize distortions Avoid surgical procedures Avoid Removal of Hearing Aids for several months Made by soft material and contour to each user Invisible and can aesthetically use User Programmable Directional to localize better sounds Increase durability of batteries Resistance to moisture and wax Increase Cosmetics purpose (Specially designed for women)

DIGITAL HEARING AIDS

Digital aids take the signal from the microphone and convert it into "bits" of data - numbers that can be manipulated by a tiny computer chip in the hearing aid. This makes it possible to modify and process sounds very precisely in ways that are impossible with analog aids. The digital chip takes the bits representing the sound and analyzes and manipulates them using what is called DSP or Digital Signal Processing.  The digital sound representations can be manipulated in almost any way imaginable, and this is what gives the digital hearing aid its big advantage. 

Invisible In canal hearing aids (IIC)

This type of hearing aid fitting is not visible when worn. This is because it fits deeper in the canal than other types, so that it is out of view even when looking directly in to the ear bowl (concha).

Downsides

Chance of getting coated with wax

RECIEVER IN THE CANAL HEARING AID

At a first glance, these devices are similar to the BTE aid. There is however one crucial difference .

The sound of the hearing aid is arguably smoother than that of a traditional BTE hearing aid. With a traditional BTE hearing aid, the amplified signal is emitted by the speaker (receiver) which is located within the body of the hearing aid (behind the ear). The amplified signal is then directed to the ear canal through an acoustic tube, which creates a peaky frequency response. With a RITE hearing aid, the speaker (receiver) is right in the ear canal and the amplified output of the hearing aid does not need to be pushed through an acoustic tube to get there, and is therefore free of this distortion.

OPEN FIT DEVICES

"Open-fit" or "Over-the-Ear" OTE hearing aids are small behind-the-ear type devices. This type is characterized by a small plastic case behind the ear, and a very fine clear tube running into the ear canal. Inside the ear canal, a small soft silicone dome or a molded, highly vented acrylic tip holds the tube in place.

Downsides

The open ear hearing aids have small batteries with short battery lives.

One of the most baffling problem with this device is that the plastic tubing might get cracked. So, one needs to take care of the hearing aid in such a

way that it remains protected, both from you and others.

BONE ANCHORED HEARING AIDS (BAHA)

The BAHA is an auditory prosthetic which can be surgically implanted. The BAHA uses the skull as a pathway for sound to travel to the inner ear. For people with conductive hearing loss, the BAHA bypasses the external auditory canal and middle ear, stimulating the functioning cochlea.

Downsides

A small surgical procedure is required to insert the implant BAHA some time cause skin infections

DISPOSIBLE HEARING AIDS

Disposable hearing aids are hearing aids that have a non-replaceable battery. These aids are designed to use power sparingly, so that the battery lasts longer than batteries used in traditional hearing aids. Disposable hearing aids are meant to remove the task of battery replacement and other maintenance chores (adjustment or cleanings).

Downsides

While disposable hearing aids have their advantages, they also have a few disadvantages.

They are not a long-term solution for hearing loss, so you have to buy one every month or so. Traditional designs can last as long as five years

Another problem with disposable hearing aids is their fit. They are manufactured to fit approximately 80% of the people who need them. Since they are not custom-fitted, it may be uncomfortable for you to wear disposable hearing aids. An improper fit can also cause feedback from the device.

SOLAR EAR

The Solar Ear unit is a palm sized device that charges two AA rechargeable Ni-Mh (1600mAh) batteries through its solar panel.

In direct sunlight the unit should take between 6 -8 hours to fully charge these batteries, which should retain the charge for about a week and also power the hearing aid/hearing aid batteries for about this time too.

The batteries are thought to have a lifespan of around 2-3 years/300 charges, this compares well to traditional hearing aid batteries that are replaced weekly.

Downsides

So if the lights go out, not only can you not see, but you're deaf as well?

CROS AND BICROS HEARING AIDS

CROS (Contralateral Routing of Signal) and BiCROS hearing aids are an option for patients with single sided deafness, or patients who have useable hearing in only one ear.

CROS With a CROS hearing aid, sound from the poor ear is transmitted to the

better hearing ear, allowing the patient to hear sounds presented to the poor side.

BICROS With a BiCROS system, 2 devices are worn when the better ear also needs

some amplification. In the poor ear, a transmitter send sound from the poor side to the better side where it is amplified.

Downsides

Often has an external wire linking the two parts which may be damaged Is clearly visible Some people report poor sound quality if hearing in better ear is normal.

EXTENDED WEAR HEARING AIDS LYRICS

Lyric® is the first and only extended wear hearing device that is 100% invisible.

The placement of Lyric in the ear canal makes it totally invisible.

No one will know why you are hearing better except you. Lyric can be used during your daily activities, such as

exercising, showering, talking on the phone, and sleeping. There are no batteries to change, no maintenance is

needed, and no daily insertion or removal is required. A proprietary battery designed to last up to 120 days Lyric’s placement deep in the ear canal allows the outer

ear (the pinna) to direct sound into the ear canal naturally.

Individuals eligible for using Lyrics Lyric is designed for people with mild to moderately-

severe hearing loss. A Lyric trained hearing professional will assess hearing loss, ear size and shape, medical conditions, and lifestyle to determine if Lyric is the right choice.

Downsides

• Only about 50% of patients with hearing loss are eligible to use the device, the company says. That’s because many people have ear canals too small or not straight enough to fit it, or because they have medical limitations.

• Downsides also include its high cost—about $3,000 to $4,000 for a year’s subscription for both ears, which includes up to eight

devices a year, as needed. Some patients experience pain or irritation in the ear, resulting in the need for the device to be removed for at least a few days.

VARIBEL THE HEARING GLASSES

Two of the big problems with current hearing aids are that (1) they can't differentiate between desired sounds and undesired

sounds, and (2) they can't tell the direction a particular sound is coming from.

You will probably remember the combination glasses and hearing aids. Researchers have just put the finishing touches on a prototype pair of 'hearing glasses'.

In each arm of the glasses is a row of four tiny microphones. They intensify sounds from the front, while dampening surrounding noise.

The output from the micro-phones is relayed to each ear by two tiny, almost invisible tubes. The wearer chooses what they hear by looking in the relevant direction.

The integrated signal is sent to a coil located in the earpiece. The device is battery operated, rechargeable and the glasses can be stored in a charging cradle when not in use.

Individuals eligible for using varibel

The Varibel is suitable for people with hearing loss up to 85 dB.

Downsides

If you have two or more pairs of glasses–unless you want to pay for two or more sets of hearing aids you have to decide which pair of glasses have the hearing aids in them. For example, say you had reading/computer glasses and driving glasses

When you take your glasses off, you also have to take your hearing aids off. For example, one lady remembered, “Every time I went to the eye doctor, I would have to take off my glasses and my hearing aids. Thus I could neither lipread nor hear during the eye appointments.”

Even worse is if either the hearing aid or the glasses break, you lose both your eyes and both your ears at the same, leaving you deaf and blind to whatever degree your hearing and vision are defective.

RESOUND ALERA BLUETOOTH HEARING AID

ReSound Alera is the industry’s first truly wireless hearing aid. So, with this new ReSound Alera hearing aid, users can also hook up with TV or cell phone wirelessly via a mini transmitter box that will transmit the TV / mobile phone sounds directly into the hearing aid.

“Other wireless technologies used in the hearing industry require the user to wear inconvenient accessories around their neck,” there is no intermediary device, the signal goes directly to the hearing aid and users have complete freedom.”

Downside

Bluetooth technology simply requires too much battery power to fully integrate with what the hearing aid must do.

INVENTION AWARD WINNING HEARING AID SOUND BITE

SoundBite, a device designed for people with single-sided deafness.

Abolfathi knew that bone was a good sound conductor. What if he could somehow make a removable oral hearing aid—one that could channel sound from wearers’ teeth to their ear through the bones in their head?

WORKING OF SOUND BITE

A microphone in the deaf ear beams incoming sound to a receiver on the tooth insert, which transmits it through the jaw to the cochlea.  

Individuals eligible to use sound bite

The best remedy for single-sided deafness currently on the market is a bone-anchored hearing aid (BAHA), which, like the SoundBite, uses direct bone conduction to deliver sound to the cochlea. But BAHA installation involves surgically implanting.

The SoundBite restores hearing just as effectively as a BAHA but requires no surgery. Instead it can be popped in and out of the mouth like a retainer.

Downsides

How are you going to talk and eat with this? You're still wearing a BTE so cosmesis is not improved.

WIREAR

The existing range of hearing aids is classified as: Completely-In-The-Ear, In-The-Canal, In-The-Ear and Behind-The-Ear. Wirear is a new type of hearing aid.

The internal components are arranged in a linear form rather than stacked.

In this format Wirear provides more space inside without adding bulk, resolving the issue of cramped components in a small housing, an identified problem with existing hearing aids.

Wirear utilises a micro fuel cell, a miniature version of fuel cell that uses hydrogen from any hydrocarbon fuel. This technology is yet to be commercialized however; it is a proven technology as the power source of the future.

A 2 ㎠ of micro fuel cell has an estimated life of six

years in this type of application proving a more sustainable energy source than the current zinc-air batteries that last approximately three weeks in this application.

Individual eligible for using wirear

Designed for people with mild to moderately-severe hearing loss.

Downsides

Placement is absolutely wrong, so no one did it before, because then you kill both the directional microphone feature.

It almost covers entire ear, it would be annoying for daily use.

PERSONAL PROGRAMMABLE OR CONSUMER PROGRAMMABLE

It means that an audiologist can modify a hearing aid’s settings for your personal hearing loss – it also means that they can set the aid up so that you can hear the sounds that you want to hear in your everyday environments.

There will default options for common situations such as: at home, at a party, at the theatre, listening to music, and so on. You can ask your audiologist to modify these to suit your needs.

Programmable hearing aids of this type offer a number of adjustable parameters which are intended to enable the optimum matching of the electro-acoustic behavior of the hearing aid to the hearing impairment to be compensated. At the same time, however, the adaptation becomes increasingly difficult for the hearing aid acoustician because of the number of parameters and the multitude of possible setting combinations arising therefore. This can lead to a faulty adaptation of the hearing aid or to a non-optimum utilization of all adaptation possibilities

ANGEL EARS HEARING AID FOR WOMEN

FUTURE DIRECTIONS

ORMIA OCHRACEA

FUTURE DIRECTIONS

Humans detect the direction a sound comes from by comparing the difference in time of arrival, or loudness of the sound reaching our two ears.

We are able to this because our ears are separated by the width of our head. A sound wave traveling from the left reaches the left ear sooner, and is louder than at the right ear.

How would this be different if our ears were right next to each other?

Scientists puzzled about this very question when studying very small insects, such as the tiny parasitic fly

Ormia ochracea

Ormia females deposit their larvae inside a live cricket. The larvae develop inside the cricket before they emerge, eventually killing the host.

The females locate crickets by ear, using only the sound of cricket chirps to guide them. However, with ears separated by less than half of a millimeter, the time and intensity difference between a fly’s ears should be much too small to detect. How do Ormia do it?

It turns out that the Ormia ear is quite unusual. The fly’s two ear drums are connected in the middle by a small bridge. The connection between the two ears is a form of mechanical coupling. It basically acts as an amplifier of the minute differences between the two ears. The unique anatomy allows Ormia flies to accurately detect the direction of sounds that would be impossible for other insects their size.

The discovery also has exciting potential applications for humans.

Development is already underway for a small hearing aid containing a microsensor patterned after the Ormia fly’s ear. The new hearing aid would allow people with hearing in only one ear to localize sound, something that current hearing aids can’t do.

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