Hearing aids essentially fill the gap created by a hearing loss. This is done by receiving and amplifying sound. There are two types of hearing aid technology that serve as the basis for receiving and amplifying sound within a hearing aid: Analog Technology and Digital Technology.
Hearing aid technology can be divided into two general categories: analog hearing aids and digital hearing aids. In very simple terms, analog and digital refer to how the hearing instrument's amplifier processes sound. Both of these categories can be further divided into more specific subcategories:
Analog hearing aids amplify the continuous sound wave by simply making it larger. There are two subcategories of analog hearing instruments: conventional hearing aids and programmable hearing aids. Conventional and programmable hearing instruments differ in the amount and degree of adjustments the hearing aid dispenser can perform on the hearing device. A programmable hearing device allows the dispenser to adjust the amplifier more precisely to match your hearing loss. Programmable analog hearing devices, when compared to their conventional equivalent, provide greater fitting flexibility. This means that the dispenser can more readily change the way a programmable analog hearing device operates through the use of an office computer. Sometimes the added flexibility of a programmable hearing aid is an important feature.
Digital hearing aids take the continuous sound wave and break it up into very small, discrete bits of information. This is called digitizing the signal and all digital hearing aids do this. The very fact that a hearing device is digital does not make it better than a comparable analog hearing aid device. Beyond just digitizing the sound prior to amplification, there are differences in exactly how various digital hearing aid devices amplify or process sound. The more sophisticated digital hearing aids are able to amplify the softest sounds of speech while at the same time subtracting out certain types of unwanted noises. Digital signal processing allows hearing aid designers to write computer programs, called algorithms that can be customized to each individual's hearing loss. In addition, digital hearing aids enable important features -- such as dual microphones and low battery warning signals -- to be placed into a small in-the-ear device. It is this potential that makes digital hearing devices so promising for so many hearing losses. Selecting the type of hearing aid that is right for your hearing loss and unique listening needs requires the guidance of a professional well versed in all of variations of hearing instrument technology. Today, over 75% of all hearing aids sold are digital.
Hearing aids worn in the ear are usually custom-fit, based on a cast or impression of the ear. They’re available in different skin tones to camouflage with the outer ear. There are several styles – each is listed below, ranging from smallest to largest.
The smallest custom style, IIC instruments site invisibly in or past the second bend of the ear canal. IIC are specifically designed for mild to moderate hearing loss.
The smallest custom style, CIC instruments fit deeply and entirely within the ear canal. They fit mild to moderate hearing losses and offer high cosmetic appeal as they’re nearly invisible when worn.
ITC instruments sit in the lower portion of the outer ear bowl, making them comfortable and easy to use. Because they’re slightly larger than CIC models, they have a longer battery life, and can host additional features such as directional microphones for better understanding in noisy environments, and controls such as volume controls. They fit mild and moderate hearing losses.
Full shell models sit flush within the outer ear bowl. Their size allows the maximum number of additional controls and features such as directional microphones, which require space on the outer portion of the instrument. They use a larger battery size than the smaller styles, and can fit a larger receiver with enough power for even some severe hearing losses. Because of their flexibility, they’re widely recommended for mild to severe hearing loss.
Behind-the-Ear (BTE) models sit behind or on top of the outer ear, with tubing that routes sounds down into the ear that connects to an ear tip or earmold to secure them in the ear canal. BTEs come in colors to blend with hair or skin tones, and even chrome colors, leopard print and other funky designs to suit personal styles. Different BTE sizes accommodate different features, controls, battery types and degrees of power (larger instruments generally have more power than smaller ones). While many people choose discreet BTEs that are unnoticeable when worn, others are tempted to show off the cool designs.
Mini BTEs are designed to hide behind the outer ear, and have ultra-thin tubing to discreetly route sound into the ear. The tubing connects to a soft tip that sits in the ear canal but doesn’t occlude it. The result is a natural, open feeling as airflow and sound enter the ear naturally around the tip, while amplified sound enters through the tip. This is known as “open fitting” and is recommended for mild to moderate high frequency losses.
RITE models, also known as RIC (receiver-in-canal) models, are mini BTEs that have the speaker of the instrument incorporated in the ear tip, instead of in the main body of the instrument. RITE instruments fit mild to severe hearing losses. This hearing aid style looks similar to the Mini BTE when worn on the ear.
BTEs with earmolds fit mild through profound hearing losses. Their longer shape, following the contour behind the outer ear, generally can house more features, controls, and power than custom models. The earmold color and style, as well as the wearer’s hairstyle, determine exactly how they’ll look on each person.