Hearing aids are available in a variety of styles, shades and technologies. They also offer many different features. As a rule, devices that are smaller, programmable or employ digital technology are more expensive.
STYLES OF HEARING AIDS
The Behind-the-Ear (BTE) device consists of an instrument that rests behind the ear attached to a custom made earmold. This style may be used for all types and degrees of hearing loss. These devices can be packaged in a mini case depending on the type and level of hearing loss. A BTE device may be required due to medical conditions of the external auditory canal that prohibit the use of other devices.
In-the-Ear devices are a custom made product that fills the concha (the bowl of the ear) and some portion of the ear canal. A broad range of circuit designs are available that allow these devices to be used in individuals with a mild to severe hearing loss. These devices are easy to manipulate for those with poor vision or manual dexterity problems.
These devices are smaller than ITEs and fit only in the outer portion of the ear canal. ITCs are suitable for patients with an adequate sized ear canal, mild-to-moderate hearing loss, and no moisture or skin problems of the ear.
This is the smallest device available and is cosmetically desirable because it fits deep in the canal and takes advantage of the ear's natural resonance and shape. Most patients are able to use these hearing aids with the telephone without experiencing feedback. CICs require good manual dexterity, a normal outer ear canal and no medical conditions that would prevent their use. CICs require a precise fit as they are seated deeply within the ear canal. Digital CICs are generally the most expensive amplification devices available due to their size and advanced technology.
COMPARING DIGITAL AND ANALOG HEARING AIDS
The terms "analog" and "digital" essentially refer to how a hearing instrument's amplifier processes sound. Digital and programmable analog devices are available in all styles, including CIC.
Analog Hearing Aids
Analog hearing aids amplify sound by making the continuous sound wave larger. There are two types of analog hearing aids:
Conventional Analog Hearing Aid specifications are prescribed by the hearing care professional and built into the hearing aid by the manufacturer. Fine tuning can be done manually in the office or at the hearing aid factory, but the hearing care professional is limited in the amount and degree of adjustments that can be made.
Programmable Analog Hearing Aids can be adjusted or modified in the office using a computer in lieu of factory or manual adjustment. This approach can offer a greater degree of flexibility in adjusting the hearing aid. These devices cost more than analog aids and sometimes have the added feature of a remote control or multiple response programs for use in different listening environments.
Digital Hearing Aids
Digital hearing aids take the continuous sound wave and break it up into tiny pieces of information. This process is called "digitizing" the signal and it allows the hearing aid manufacturer to write specialized computer programs that allow your hearing care professional to customize your hearing aid to your unique listening needs.
Advantages of digital technology include greater precision in adjusting characteristics and more complex sound processing. Digital instruments can have special features to help the user such as dual microphones and low battery warning signals. Loudness adjustments are made automatically. The more sophisticated digital hearing instruments are able to amplify the softest sounds of speech while at the same time subtracting out certain types of unwanted noises. These hi-tech systems may be used with a wide range of hearing losses. Although they are the most expensive hearing aids on the market today, due to their sophistication and benefits, they represent the highest percentage of hearing aids dispensed.
CROS & BiCROS AIDS
CROS (Contralateral Routing of Signal) and BiCROS hearing aids may be useful for patients who have useable hearing in only one ear. A hearing aid is worn in each ear. Sound from the hearing impaired ear is transmitted to the better hearing ear, allowing the patient to hear sounds presented to the impaired side. BiCROS hearing aids are sued when the better ear also needs some amplification. These devices may be helpful in small meetings or dinner-table situations.
ONE OR TWO HEARING AIDS?
A major problem faced by people with hearing loss is understanding conversation in the presence of background noise or when more than one person is speaking—such as at social gatherings, restaurants and auditoriums. Hearing loss makes understanding speech even more difficult than normal in background noise or in rooms with poor acoustics.
Modern hearing aids are wonderful devices, but they do not fully resolve this problem. If you have a hearing loss in both ears, it is important that you wear an aid in each ear. This will maximize your ability to understand because speech intelligibility in noise depends on the ability to localize sound. When wearing only one hearing instrument, it becomes difficult to identify the direction or source of a sound.