Audiology

Audiology is the branch of health sciences concerned with the evaluation of the hearing and balance system, as well as the diagnosis and rehabilitation of hearing loss. Hearing is one of the most fundamental senses that enables humans to communicate with their environment, and hearing loss can lead to serious communication difficulties, social isolation, and a decline in quality of life across all age groups. The Audiology Department at Koru Hospital provides comprehensive services in the field of hearing health with advanced technological audiological assessment devices and an expert staff.

Physiology and Importance of Hearing

The hearing process occurs as sound waves enter the external ear canal and vibrate the eardrum; these vibrations are transmitted to the inner ear via the ossicles in the middle ear, and the cochlea in the inner ear converts the sound waves into electrical signals, which are then transmitted to the brain via the auditory nerve. A disorder at any point in this complex process can lead to hearing loss.

Hearing is essential not only for perceiving sounds but also for understanding speech, noticing environmental dangers, maintaining social interaction, and forming emotional bonds. Especially during childhood, hearing is the fundamental building block of language development and cognitive growth. Therefore, the timely detection of hearing loss and the provision of appropriate intervention are of great importance.

Types of Hearing Loss

Hearing losses are classified into three main categories based on the localization of the disorder. The causes, symptoms, and treatment approaches for each type differ from one another.

• Conductive Hearing Loss: This is a type of hearing loss caused by pathologies in the outer or middle ear. Earwax accumulation, eardrum perforation, otitis media, otosclerosis, and ossicular chain disorders are among the most common causes. Conductive hearing losses can often be corrected with medical or surgical treatment.
• Sensorineural Hearing Loss: This is a type of hearing loss caused by damage to the inner ear (cochlea) or the auditory nerve. Age-related hearing loss (presbycusis), noise-induced hearing loss, genetic factors, ototoxic drugs, Meniere's disease, and acoustic neuroma are the primary causes. Sensorineural hearing losses are generally permanent and are rehabilitated with hearing aids or cochlear implants.
• Mixed Hearing Loss: This is a condition where both conductive and sensorineural hearing loss are present. Pathology exists in both the outer or middle ear and the inner ear or neural pathway.

Causes of Hearing Loss

Hearing loss can stem from many different causes. Accurately identifying these causes is critical for establishing an appropriate treatment and rehabilitation plan.

• Age-Related Hearing Loss (Presbycusis): It develops as a result of the degeneration of sensory cells in the inner ear due to aging. It is a progressive hearing loss that usually affects both ears symmetrically and begins at high frequencies. It is seen in approximately one-third of individuals over the age of 65.
• Noise-Induced Hearing Loss: It develops due to damage to the hair cells in the inner ear resulting from long-term exposure to high-decibel sounds. Occupational noise exposure, listening to loud music, and exposure to explosive sounds are the primary risk factors.
• Genetic Hearing Loss: A significant portion of congenital or progressive hearing losses is genetic in origin. It is examined in two groups: syndromic and non-syndromic.
• Infections: Measles, mumps, meningitis, syphilis, and cytomegalovirus infections can cause hearing loss. Infections during pregnancy, in particular, can lead to permanent hearing loss in the fetus.
• Ototoxic Drugs: Aminoglycoside antibiotics, chemotherapy drugs such as cisplatin, high-dose aspirin, and certain diuretics can have a toxic effect on the inner ear.
• Trauma: Head trauma, temporal bone fractures, and acoustic trauma are among the significant causes of hearing loss.

Audiological Assessment Methods

Various audiological tests are applied in the diagnosis of hearing loss and the determination of its degree. These tests are selected based on the patient's age, complaints, and clinical condition.

• Pure Tone Audiometry: This is the fundamental audiological test used to determine hearing thresholds specific to frequency. The type and degree of hearing loss are determined by measuring air conduction and bone conduction hearing thresholds.
• Speech Discrimination Test: This test, which evaluates the patient's ability to understand speech sounds, provides important information for planning hearing aid applications and determining cochlear implant candidacy.
• Tympanometry: It is used to evaluate middle ear pressure, eardrum mobility, and Eustachian tube function. It is helpful in detecting middle ear fluid, eardrum perforation, and ossicular chain pathologies.
• Acoustic Reflex Test: The integrity of the auditory pathway is evaluated by measuring the reflex response of the stapedius muscle. It is an important test for screening retrocochlear pathologies.
• Otoacoustic Emission (OAE): This is an objective test that evaluates the function of the outer hair cells in the inner ear. It is widely used in newborn hearing screenings.
• Auditory Brainstem Response (ABR): It is used for the electrophysiological evaluation of the auditory pathways at the level of the auditory nerve and brainstem. It is preferred for the objective determination of hearing thresholds in newborns and non-cooperative patients.

Newborn Hearing Screening

Newborn hearing screening is a vital program implemented to detect congenital hearing loss at an early stage. Approximately one to three out of every thousand newborns have congenital hearing loss. Early diagnosis and intervention are critical for the child's language, speech, and cognitive development to proceed normally.

In the screening program, the otoacoustic emission (OAE) test is applied first, and in case of a failed result, further evaluation is performed with the ABR test. For infants diagnosed with hearing loss, the goal is to initiate intervention before the age of six months.

Hearing Aids

Hearing aids are the most commonly used technological solutions in the rehabilitation of hearing loss. Modern digital hearing aids amplify sounds in a personalized manner according to the patient's hearing loss profile.

• Behind-the-Ear (BTE) Aids: These are devices placed behind the ear that transmit sound to the ear canal via a tube. Due to their high amplification capacity, they can be used for all levels of hearing loss, from mild to profound.
• In-the-Ear (ITE) Aids: These are devices placed inside the ear canal, which are more preferred for cosmetic reasons. They are applied for mild to moderate hearing losses.
• In-the-Canal (CIC/IIC) Aids: These are devices placed deep into the ear canal that are almost invisible from the outside. They are a suitable option for patients with cosmetic concerns.
• Receiver-in-Canal (RIC) Aids: These are modern devices with the receiver unit in the ear canal and the main body behind the ear. Due to their natural sound quality and small size, they are the most preferred type of hearing aid today.

The selection of a hearing aid is made in a personalized manner, taking into account factors such as the type and degree of hearing loss, ear anatomy, lifestyle, expectations, and budget. The fitting and adjustment process performed by the audiologist is of great importance for achieving the best performance from the device.

Cochlear Implant

A cochlear implant is a surgical solution applied to patients with severe to profound sensorineural hearing loss who cannot derive sufficient benefit from hearing aids. The device converts sound waves into electrical signals to directly stimulate the auditory nerve.

Comprehensive audiological tests, radiological imaging, and multidisciplinary team evaluation are conducted to assess cochlear implant candidacy. The successful completion of the post-operative programming and auditory rehabilitation process are the most important factors determining the effectiveness of the implant.

Tinnitus Management

Tinnitus is the perception of sound in the ear or head without any external sound source. This condition, which can be described as ringing, buzzing, humming, or hissing, affects approximately ten to fifteen percent of the population.

• Tinnitus Assessment: Determining the frequency, intensity, and type of tinnitus is important for creating a treatment plan.
• Sound Therapy: It aims to reduce the perception level of tinnitus by using environmental sounds or special sound generators.
• Tinnitus Retraining Therapy (TRT): It aims to achieve habituation to tinnitus through a combination of counseling and sound therapy.
• Cognitive Behavioral Therapy: It is an effective psychotherapy method for managing symptoms of anxiety and depression caused by tinnitus.

Balance Assessment (Vestibular Tests)

In addition to hearing assessment, the Audiology Department also evaluates the vestibular (balance) system. A vestibular test battery is applied for patients with complaints of dizziness and balance disorders.

• Videonystagmography (VNG): It is used to evaluate the function of the vestibular system by recording eye movements.
• Video Head Impulse Test (vHIT): It allows for the rapid and reliable evaluation of the function of each semicircular canal separately.
• Vestibular Evoked Myogenic Potentials (VEMP): It is an electrophysiological test used to evaluate the function of the otoliths.

Protecting Hearing Health

Precautions to protect hearing health are important throughout life. Using ear protection in noisy environments, limiting the duration and volume of listening to music with headphones, avoiding ototoxic drugs, and having regular hearing check-ups help reduce the risk of hearing loss. For individuals working in noisy environments, annual audiological evaluations are not only a legal requirement but also of great importance for hearing health.

In the Audiology Department at Koru Hospital, our specialist physicians and audiologists provide our patients with evidence-based, personalized, and comprehensive audiological services at every stage, from the diagnosis of hearing and balance disorders to their rehabilitation. With our advanced audiological test infrastructure and experienced team, we aim to protect and improve our patients' hearing health at the highest level.