Hearing Aids ( Hearingaids )
 

Hearing Aid Features and Capabilities

Hearing aids ( hearingaids ) can be defined by:

• Hearing aid form factor
  
  i.e. what they look like and their size and where they are placed in/ on the ear (BTE, ITE, ITC, and CIC): these terms are explained later in this article. The styles are designed for specific types of hearing loss as well as lifestyle and cosmetic considerations.
   

• Technology used in a hearing aid:
  
  All hearing aids are built from either analog or digital circuitry. Digital hearing aids are the more technologically sophisticated type of hearing aids and the most expensive. As opposed to analog hearing aids, digital hearing aids are programmable and provide advantages of greater adjustment precision and more complex sound processing. With most digital hearing aids, volume adjustments are automatic.  Many of these newer hearing aids have multiple microphones for better directional hearing and sound processing for background noise reduction. For an explanation of the technical differences between analog and digital hearing aids, click here.

These two hearing aid definitions are not mutually exclusive when it comes to the outer part of the hearing aid (form factor) as both analog and digital technology have been available for most of the hearing aid styles, although most analog production has been phased out by most hearing aid manufacturers.

(BTE) Behind the ear hearing aids

All BTE hearing aids are comprised of basic parts as shown in the following diagram:

The locations of the microphones, speakers, amplifiers and batteries will differ between manufacturers. The newer and smaller open fit hearing aids replace the ear-mold with a a small "bud" or "dome" that has holes in it.

Also there is confusing terminology. For example, the hearing aid part that pushes the sounds to the  ear canal through the tube is called a "receiver" by manufacturers.  Most consumers call this component a speaker rather than a receiver.

The BTE model hearing aids come in a number of variations:

1. Analog (BTE) Behind the ear hearing aids (hearingaids)

BTE Analog Hearing Aids consist of three basic parts: the hearing aid case that fits behind the ear, a tube that connects to an an ear mold which sits inside the ear, and an ear mold. The hearing aid rests behind the ear and a plastic tube connects it to the ear mold. This was the most common type of hearing aid and at one time was the only type you could buy.

	Note the large ear-mold which is custom-made and completely fills in the ear canal and ear entrance
Behind The Ear Hearing Aid - Older Analog Version	Hearing Loss addressed- Mild to moderate hearing loss

Note the large hearing aid case behind the ear that can easily be seen from the side and the thick tube connecting the case to the mold in the ear canal.

Most European and North American companies no longer make these analog hearing aids and they now make the smaller Behind The Ear hearing aid (BTE hearing aid) with digital electronics. An example of this type of BTE hearing aid follows.

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2. Digital Behind the ear (BTE) hearing aids ( hearingaids )

BTE Digital hearing aids are much like their analog cousins on the outside: Digital BTE hearing aids are made up of the hearing aid case, a "ear hook" extension, and a tube that connects to a mold in the ear. They are similar in size to the analog hearing aids, some perhaps a little smaller. These digital BTE hearing aids also fit behind and over the ear; the ear hook part fits over the front of the ear and points down towards the ear canal. One end of a tube is connected to the opening in the ear hook end the other end connects through a tube to a mold in the ear canal.

However, as opposed to the BTE analog hearing aids, digital BTE hearing aids have a DSP (Digital Signal Processing) chip that is the "brains" of the hearing aid. These DSP chips consist of micro-circuitry much like a CPU on a computer and they also have software programs that are "burned" into the chip.

Each hearing aid manufacturer has DSP chips that they purchase from specialized chip fabrication manufactures. They then program the chips to offer their unique features amplification and filtering features.

It is the DSP on a digital hearing aid that provides some of the following capabilities:

• Multiple frequency response bands like an equalizer on a stereo

• Multiple channels that the user can switch between for different listening environments (normal conversation, Telephone, TV listening, restaurants, theater etc.)

• Noise reduction filters - minimizes noisy environmental sounds when you are talking and listening to someone

• Dynamic contrast detection - able to pick up the different verbal conversational sounds from the environment

• Multiple microphones

Because these hearing aids also require a custom mold to fit inside the ear canal, either a licensed audiologist or a licensed audiologic dispenser is required to make the mold.

Digital Behind the Ear with ear hook extension	Hearing Loss addressed: Severe to profound hearing loss

 

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3. Digital Behind the ear (BTE) Open Fit hearing aids

The digital open fit hearing aids or open ear hearing aids are all digital hearing aids and have a Digital Signal Processing chip like their BTE cousins. What makes these hearing aids different from the BTE hearing aids with the ear hook design?

• Some models are 1/2 - 1/3 the size of the fish hook BTE hearing aids. They still fit behind the ear but they are only about 1" long and about 1/4" wide which means they are very hard to see unless someone is looking intently.
• They are very light weight, some weighing in at just 1 -2 ozs.
• They do not have an ear hook extension.
• The sound tube that connects to the ear canal is very thin and opaque in color making it almost invisible.
• What really differentiates the BTE open fit hearing aids from the ear hook BTE models is that a custom ear canal mold is not required. Instead of an ear mold, a small bud is that looks like a mushroom cap is attached to one end of the sound tube and fits into the ear canal. Instead of occluding (plugging up) the ear canal, each ear bud has holes in it that allows some sounds from the environment to enter the ear canal at the same time the hearing aid is amplifying. This setup provides a much richer listening experience and allows the hearing aid wearer to better orient themselves to whoever is talking to them.

	Hearing Loss addressed: severe to profound hearing loss
Note that there is no ear mold. The small bud on the end of the tube fits into the ear canal so only the narrow, opaque tube can be seen from the side. Note also that the hearing aid case is invisible.
Digital Open Fit Hearing Aid

 

Interested in purchasing a digital open fit hearing aid?

  

 

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Digital In-the-ear (ITE) and Canal (ITC) hearing aids (hearingaids)

Digital In-the-Ear (ITE) and In-the-canal (ITC) hearing aids come in two form factors: those with a custom mold, and those with a generic tip.  Both of these types of hearing aids occlude (plug up) the ear canal so all sounds that enter the ear canal, do so through the amplification of the hearing aid.

Both models have DSP chips that provides the wide range of features:

• Multiple frequency response bands like an equalizer on a stereo

• Noise reduction - minimizes noisy environmental sounds when you are talking and listening to someone

• Dynamic contrast detection - able to pick up the different verbal conversational sounds from the environment

What is the difference between an ITE hearing aid and an ITC hearing aid? The difference is size i.e. how much of the hearing aid case can be seen outside the ear.

In-the-Ear (ITE) hearing aids fit completely in the outer ear and are used for mild to severe hearing loss. The hearing aid case, which holds the components, is made of hard plastic. Older ITE and ITC aids could also accommodate added technical mechanisms such as a telecoil, a small magnetic induction coil contained in the hearing aid that minimizes feedback (the high pitched whistling sound) during telephone calls. Newer ITC hearing aids usually do not have a telecoil because of the size requirements for the coil and the fact that the DSP chips features obviate the need for a telecoil.

In-The-Ear	In-The-Canal	Hearing Loss addressed: moderate to severe hearing loss

The ITE and ITC hearing aid models with molds are usually sold by audiologists as they require a custom mold to be made; the ITE and ITC hearing aids that have generic tips are mostly sold by mail order houses and Internet retailers.

Interested in purchasing an In The Canal hearing aid?

Completely In The Canal (CIC) hearing aids ( hearingaids )

A Completely-in-Canal (CIC) hearing aid is largely concealed in the ear canal and is used for mild to moderately severe hearing loss. One of the great advantages of the CIC hearing aid is that it cannot be seen by someone else.  However, because of their small size, CIC hearing aids may be difficult for the user to adjust and remove. Trying to poke a finger into the ear canal to adjust a CIC hearing aid can be very frustrating.   Because of their proximity to the wax glands, Completely In the Canal hearing aids can also be easily damaged by earwax and ear drainage. They are not typically recommended for children.

CIC models have DSP chips that provides a wide range of features:

• Multiple frequency response bands like an equalizer on a stereo

• Noise reduction - minimizes noisy environmental sounds when you are talking and listening to someone

• Dynamic contrast detection - able to pick up the different veral conversational sounds from the environment

Completely in-The Canal

Although the advantage of the CIC aid style is the small size, the disadvantages of higher cost, and the extreme difficulty in adjusting are often not worth the effort or cost.

So, what IS the best hearing aid to buy?

If you have a moderate to severe hearing loss (up to 60 dB loss at any frequency):

• If you are vain and don't want people knowing you have a hearing aid, then purchase a CIC model hearing aid. But be aware they will easily get clogged with ear wax, and the volume adjustment is impossible without taking the hearing aid out of the ear. CIC hearing aids are not practical for remediation of hearing losses above 60dB as they are too small for the necessary amplification technology to fit into such a small size. Also the fact they are deep in the ear canal means that many frequencies will not reach the hearing aid to be amplified.
• If you want a discrete yet slightly visible hearing aid, and want an in the ear model, then choose and ITC or an ITE hearing aid. (Note: some of these hearing aid models can also  remediate severe hearing loss (60 - 80 dB))

If you have a severe to profound hearing loss in the higher frequencies (up to 110dB in the 2K+ hertz rate):

• Choose an Open Fit BTE hearing aid model. Why? They are much lighter than the regular digital BTE hearing aids and are more comfortable, and can easily be worn with eyeglasses. BTE Open Fit hearing aid models also easy to take off, clean, and switch between the various listening modes (normal, telephone, TV, restaurant etc.)

If you have severe -to profound hearing loss especially in the lower frequencies (up to 80 dB below 2K Hertz)

• Choose either a regular BTE hearing aid or a modified Open Fit BTE hearing aid model that has the  speaker in the ear (SIE) configuration. Why? The speaker in the ear configuration takes all available external frequencies and amplifies them to the ear drum. These models will not have any holes in them for external sounds to bypass the hearing aid; all sounds come through the hearing aid itself. The downside is that these SIE hearing aid models have the speaker in the ear often have potential problems with whistling feedback unless the mold or bud that goes in the ear canal fits snugly.