Journal of Biomedical Engineering and Medical Devices
Open Access

Hearing Aid: An Overview

Wei Li^{* *}Correspondence: Wei Li, Hong Kong Metropolitan University, Ho Man Tin, Hong Kong, Email:

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Perspective

A hearing aid is a device that helps people with hearing loss hear better by amplifying sound. In most countries, hearing aids are categorised as medical equipment and are subject to specific laws. Small audio amplifiers, such as PSAPs or other simple sound reinforcement systems, are not permitted to be marketed as "hearing aids." Ear trumpets and ear horns were early passive amplification cones that collected sound energy and directed it into the ear canal. Modern devices are computerised electroacoustic systems that use audiometrical and cognitive criteria to turn environmental sound into audible sound. Modern gadgets also employ advanced digital signal processing in order to increase speech intelligibility and user comfort. Feedback management, wide dynamic range compression, directionality, frequency lowering, and noise reduction are examples of signal processing. Modern hearing aids must be customised to the wearer's hearing loss, physical characteristics, and lifestyle. The hearing aid is programmed by frequency and is fitted to the most recent audiogram. Fitting is a process that is carried out by a Doctor of Audiology, usually known as an audiologist (AuD), or a Hearing Instrument Specialist (HIS).

The effectiveness of a hearing aid is largely determined on the quality of its fitting. In the United States, almost all hearing aids are digital.

The osseointegrated auditory prosthesis (previously known as the bone-anchored hearing aid) and cochlear implant are devices that are similar to hearing aids. Sensorineural hearing loss, conductive hearing loss, and single-sided deafness are all conditions that hearing aids are used to treat. Hearing aid eligibility is usually determined by an audiologist, who will also fit the device based on the kind and severity of the hearing loss being treated. The kind, degree, and aetiology of the hearing loss, as well as the technology and fitting of the device, as well as the user's motivation, personality, lifestyle, and overall health, all influence the amount of benefit received by the hearing aid user. Hearing aids are only capable of making sounds more audible, not totally repairing a hearing loss. Sensorineural hearing loss, which results from damage to the hair cells and synapses of the cochlea and auditory nerve, is the most frequent type of hearing loss for which hearing aids are sought. Sensorineural hearing loss diminishes sound sensitivity, which a hearing aid can partially compensate for by increasing sound volume. Other auditory impairments induced by sensorineural hearing loss, such as aberrant spectral and temporal processing, which can negatively affect speech perception, are more difficult to compensate for using digital signal processing and, in some situations, may be aggravated by amplification. Hearing aids are superior at treating conductive hearing deficits, which do not involve damage to the cochlea; the hearing aid is able to properly amplify sound to compensate for the conductive component's attenuation. The cochlea and auditory nerve can transport messages to the brain normally after sound reaches normal or near-normal levels in the cochlea.

The occlusion effect, loudness recruitment, and interpreting speech amid noise are all common challenges with hearing aid fitting and use. Feedback, which was once a widespread issue, is now generally well-controlled because to the introduction of feedback management algorithms. There are numerous methods for determining how effective a hearing aid is at compensating for hearing loss. Audiometry is one method, which involves measuring a subject's hearing levels in a laboratory setting. In a variety of settings, the audibility threshold for various sounds and intensities is measured. Despite the fact that audiometric tests seek to simulate real-world situations, the patient's daily experiences may differ. Self-report assessment is an alternate strategy in which the patient reports on their experience with the hearing aid. Real ear measurement is the most reliable approach for determining if a hearing aid is properly adjusted. Using a silicone probe tube microphone, real ear measurements (or probe microphone measurements) are an examination of the properties of hearing aid amplification near the ear drum. Hearing aids and correct amplification are also being investigated as a treatment for tinnitus, a medical disease that causes a ringing or buzzing in the ears.

Types

Hearing aids (also known as hearing instruments) come in a variety of sizes, power levels, and circuitry configurations. There are a variety of sizes and models to choose from, including the following:

Body-worn:

Harvey Fletcher, while working at Bell Laboratories, invented the first portable electronic hearing aids, known as body worn aids. Body aids are made up of a casing and an ear-mold that are connected by a wire. The electronic amplifier components, controls, and batteries are housed in the case, while the ear-mold normally houses a small loudspeaker. The case is normally the size of a deck of cards and is worn in the pocket or on the belt. Bodyworn hearing aids can give large amplification and long battery life at a reduced cost because they don't have the size limits of smaller hearing aids. Because of their low cost, body aids are still employed in emerging markets.

Behind the ear: Behind-the-ear (BTE) hearing aids are one of two types of hearing aids: in-the-ear (ITE) and behind-the-ear (BTE) (ITE). The location of the hearing aid distinguishes these two classifications.

Behind the ear: BTE hearing aids are housed in a casing that hangs behind the ear. A standard tube, slim tube, or wire connects the case to an ear-mold or dome tip. From the superior-ventral section of the pinna to the concha, where the ear-mold or dome tip inserts into the external auditory canal, the tube or wire runs.

The electronics, controls, batteries, and microphone are all housed in the case (s). The loudspeaker, or receiver, can be contained in either the case (conventional BTE) or the ear-mold or dome tip (receiver-in-the-canal, or RIC). The RIC form of BTE hearing aid is typically smaller than a standard BTE and is preferred by more active people.

In the ear: ITE (in the ear aids) devices are worn in the outer ear bowl (called the concha). These are easy to insert and may carry more features because they are larger. When standing face to face with someone, they are occasionally visible.

Hearing aids from ITE are manufactured to order to fit each individual's ear. They can be used to treat hearing loss ranging from mild to severe. Feedback, which is a screaming or whistling sound created by sound (especially high frequency sound) leaking and being magnified again, can be an issue for people with severe hearing loss.