WHAT ARE THE TYPES OF HEARING LOSS?

Hearing loss is a common health issue that can significantly affect the quality of daily life. This condition may arise from various causes and requires different treatment approaches depending on the type of hearing loss.

Hearing loss is generally examined under three main categories: type, degree, and configuration. These classifications are of great importance both for the diagnostic evaluation process and for determining the most appropriate treatment method.

Types of Hearing Loss

1. Conductive Hearing Loss

Conductive hearing loss occurs due to problems in the outer or middle ear. It is usually temporary and treatable. Treatment methods vary depending on the underlying cause.

Individuals with conductive hearing loss typically perceive sounds as quieter, but since the transmission is not distorted, sound quality is generally preserved. Diagnosis is typically made through audiological evaluations. Tests such as pure tone audiometry, tympanometry, and acoustic reflex measurements are used to identify the location of the pathology within the conductive system. The main causes of conductive hearing loss include:

Earwax (Cerumen) Blocking the Ear Canal: Excessive or impacted cerumen can completely block the external auditory canal, preventing sound waves from reaching the eardrum. This is usually a temporary and easily treatable condition.
External Ear Infection (Otitis Externa): Also known as “swimmer’s ear,” this condition involves bacterial or fungal infection of the external auditory canal, leading to edema, pain, and conductive hearing loss.
Fluid Accumulation in the Middle Ear (Otitis Media with Effusion / Serous Otitis Media): Often resulting from viral infections, upper respiratory illnesses, or Eustachian tube dysfunction, this fluid disrupts mechanical sound transmission, causing conductive hearing loss.
Eardrum Perforation: Tears in the eardrum due to trauma, infection, or barotrauma can impair the transmission of sound to the middle ear.
Eustachian Tube Dysfunction: The Eustachian tube equalizes pressure in the middle ear with atmospheric pressure, allowing the eardrum to vibrate freely. Dysfunction leads to negative pressure and fluid accumulation in the middle ear, resulting in conductive hearing loss.
Middle Ear Infection (Acute Otitis Media): Infections of bacterial or viral origin can lead to inflammation and fluid buildup in the middle ear, limiting eardrum movement and causing hearing loss.
Fixation or Degeneration of the Middle Ear Ossicles (Otosclerosis): This condition occurs when the stapes bone becomes fixed to the oval window, blocking sound transmission to the inner ear. It is progressive and can be genetic. Surgical treatment (stapedectomy) may be an option.
Foreign Body in the Ear Canal: Common especially in children, foreign objects can mechanically obstruct the passage of sound waves to the eardrum.
Congenital Anatomical Anomalies: Malformations of the pinna, ear canal, or middle ear structures (e.g., atretic ear canal) can impair sound transmission, leading to conductive hearing loss.
Trauma and Post-Surgical Complications: Head trauma, complications following ear surgery, or temporal bone fractures may damage ear structures, disrupting sound transmission.

2. Sensorineural Hearing Loss

Sensorineural hearing loss results from a malfunction in the transmission of sound to the brain via the hair cells in the cochlea or the auditory nerve (n. vestibulocochlearis – CN VIII). This type of hearing loss is typically permanent. Unlike conductive hearing loss, sound is perceived not only as quieter but also distorted.

Diagnosis involves advanced audiological evaluations such as pure tone audiometry, speech audiometry, high-frequency testing, OAE (otoacoustic emissions), and ABR (auditory brainstem response). These tests help determine damage at the cochlear and/or central auditory pathway levels. Main causes of sensorineural hearing loss include:

Presbycusis (Age-Related Hearing Loss): Caused by degenerative changes in cochlear hair cells due to aging. It typically affects both ears symmetrically, is progressive, and impacts high frequencies. Speech intelligibility is commonly reduced.
Noise-Induced Hearing Loss: Prolonged or sudden exposure to loud sounds (e.g., machinery, explosions, loud music) can damage cochlear hair cells. A characteristic notch at 4000 Hz is usually observed on the audiogram.
Genetic and Congenital Causes: A large portion of congenital hearing loss is genetic (e.g., GJB2 gene mutations, syndromic conditions such as Usher, Pendred, Waardenburg, cochlear aplasia, hypoplasia, or inner ear dysplasias).
Ototoxic Medications: Certain drugs have toxic effects on the inner ear (e.g., aminoglycosides such as gentamicin, amikacin; chemotherapy agents such as cisplatin, carboplatin; high-dose salicylates like aspirin; loop diuretics such as furosemide) and can cause sensorineural hearing loss.
Viral and Bacterial Infections: Infections affecting the inner ear (measles, mumps, CMV, herpes viruses, bacterial meningitis, etc.) may lead to permanent hearing loss.
Meniere’s Disease: Caused by increased endolymphatic fluid in the inner ear. It typically presents with unilateral, fluctuating hearing loss, tinnitus, and vertigo. In advanced stages, permanent sensorineural hearing loss may occur.
Trauma: Head trauma (especially temporal bone fractures), barotrauma (sudden pressure changes), and cochlear contusion or nerve damage can lead to hearing loss.
Tumors: Vestibular Schwannoma (Acoustic Neuroma) is a benign tumor arising from Schwann cells of the 8th cranial nerve. It commonly causes asymmetric sensorineural hearing loss. Additional symptoms may include tinnitus, imbalance, and reduced speech discrimination.

3. Mixed Hearing Loss

Mixed hearing loss refers to the presence of both conductive and sensorineural components. It results from a combination of issues affecting both the transmission of sound through the outer/middle ear and its processing in the inner ear or auditory nerve. Individuals with mixed hearing loss experience difficulty due to problems in both conducting and interpreting sound waves.

This combined pathology makes the clinical course more complex. Patients perceive sounds as both quieter and distorted. Hearing loss is often permanent.

Diagnosis is made via pure tone audiometry. Both air and bone conduction thresholds are elevated, with a significant air-bone gap observed. Additional assessments such as tympanometry, acoustic reflex testing, ABR, and OAE are used for further evaluation. Main causes of mixed hearing loss include:

Chronic Otitis Media and Secondary Cochlear Damage: Long-standing middle ear infections, eardrum perforation, or cholesteatoma may lead to toxic or inflammatory damage in inner ear structures over time, resulting in combined hearing loss.
Traumatic Injuries: Temporal bone fractures can cause both conductive issues (e.g., ossicular chain dislocation/fixation) and direct damage to the cochlea or auditory nerve.
Cochlear Extension of Otosclerosis (Cochlear Otosclerosis): Otosclerosis, typically presenting as conductive hearing loss, may in some cases spread to the cochlea, resulting in additional sensorineural components.
Post-Surgical Damage: Middle ear surgeries (e.g., stapedectomy, tympanoplasty) can occasionally cause inner ear trauma or toxicity, leading to mixed hearing loss.
Extensive Spread of Infections: Infections such as bacterial meningitis or otitis media may affect both middle and inner ear structures, causing combined hearing loss.
Congenital Syndromes with Anatomical Anomalies: Some congenital syndromes involve malformations in both outer/middle and inner ear structures, leading to mixed hearing loss.

Accurate diagnosis and differential evaluation are essential for determining appropriate treatment and rehabilitation strategies. Early audiological evaluation is crucial in suspected hearing loss to prevent permanent effects and improve quality of life.

📞 If you are seeking professional support for hearing loss in Cyprus, contact İskele Hearing Center today. For more information or to book an appointment, feel free to reach out to us.

Types of Hearing Loss

1. Conductive Hearing Loss

Conductive hearing loss occurs due to problems in the outer or middle ear. It is usually temporary and treatable. Treatment methods vary depending on the underlying cause.

Earwax (Cerumen) Blocking the Ear Canal: Excessive or impacted cerumen can completely block the external auditory canal, preventing sound waves from reaching the eardrum. This is usually a temporary and easily treatable condition.

External Ear Infection (Otitis Externa): Also known as “swimmer’s ear,” this condition involves bacterial or fungal infection of the external auditory canal, leading to edema, pain, and conductive hearing loss.

Fluid Accumulation in the Middle Ear (Otitis Media with Effusion / Serous Otitis Media): Often resulting from viral infections, upper respiratory illnesses, or Eustachian tube dysfunction, this fluid disrupts mechanical sound transmission, causing conductive hearing loss.

Eardrum Perforation: Tears in the eardrum due to trauma, infection, or barotrauma can impair the transmission of sound to the middle ear.

Eustachian Tube Dysfunction: The Eustachian tube equalizes pressure in the middle ear with atmospheric pressure, allowing the eardrum to vibrate freely. Dysfunction leads to negative pressure and fluid accumulation in the middle ear, resulting in conductive hearing loss.

Middle Ear Infection (Acute Otitis Media): Infections of bacterial or viral origin can lead to inflammation and fluid buildup in the middle ear, limiting eardrum movement and causing hearing loss.

Fixation or Degeneration of the Middle Ear Ossicles (Otosclerosis): This condition occurs when the stapes bone becomes fixed to the oval window, blocking sound transmission to the inner ear. It is progressive and can be genetic. Surgical treatment (stapedectomy) may be an option.

Foreign Body in the Ear Canal: Common especially in children, foreign objects can mechanically obstruct the passage of sound waves to the eardrum.

Congenital Anatomical Anomalies: Malformations of the pinna, ear canal, or middle ear structures (e.g., atretic ear canal) can impair sound transmission, leading to conductive hearing loss.

Trauma and Post-Surgical Complications: Head trauma, complications following ear surgery, or temporal bone fractures may damage ear structures, disrupting sound transmission.

2. Sensorineural Hearing Loss

Presbycusis (Age-Related Hearing Loss): Caused by degenerative changes in cochlear hair cells due to aging. It typically affects both ears symmetrically, is progressive, and impacts high frequencies. Speech intelligibility is commonly reduced.

Noise-Induced Hearing Loss: Prolonged or sudden exposure to loud sounds (e.g., machinery, explosions, loud music) can damage cochlear hair cells. A characteristic notch at 4000 Hz is usually observed on the audiogram.

Genetic and Congenital Causes: A large portion of congenital hearing loss is genetic (e.g., GJB2 gene mutations, syndromic conditions such as Usher, Pendred, Waardenburg, cochlear aplasia, hypoplasia, or inner ear dysplasias).

Ototoxic Medications: Certain drugs have toxic effects on the inner ear (e.g., aminoglycosides such as gentamicin, amikacin; chemotherapy agents such as cisplatin, carboplatin; high-dose salicylates like aspirin; loop diuretics such as furosemide) and can cause sensorineural hearing loss.

Viral and Bacterial Infections: Infections affecting the inner ear (measles, mumps, CMV, herpes viruses, bacterial meningitis, etc.) may lead to permanent hearing loss.

Meniere’s Disease: Caused by increased endolymphatic fluid in the inner ear. It typically presents with unilateral, fluctuating hearing loss, tinnitus, and vertigo. In advanced stages, permanent sensorineural hearing loss may occur.

Trauma: Head trauma (especially temporal bone fractures), barotrauma (sudden pressure changes), and cochlear contusion or nerve damage can lead to hearing loss.

Tumors: Vestibular Schwannoma (Acoustic Neuroma) is a benign tumor arising from Schwann cells of the 8th cranial nerve. It commonly causes asymmetric sensorineural hearing loss. Additional symptoms may include tinnitus, imbalance, and reduced speech discrimination.

3. Mixed Hearing Loss

This combined pathology makes the clinical course more complex. Patients perceive sounds as both quieter and distorted. Hearing loss is often permanent.

Chronic Otitis Media and Secondary Cochlear Damage: Long-standing middle ear infections, eardrum perforation, or cholesteatoma may lead to toxic or inflammatory damage in inner ear structures over time, resulting in combined hearing loss.

Traumatic Injuries: Temporal bone fractures can cause both conductive issues (e.g., ossicular chain dislocation/fixation) and direct damage to the cochlea or auditory nerve.

Cochlear Extension of Otosclerosis (Cochlear Otosclerosis): Otosclerosis, typically presenting as conductive hearing loss, may in some cases spread to the cochlea, resulting in additional sensorineural components.

Post-Surgical Damage: Middle ear surgeries (e.g., stapedectomy, tympanoplasty) can occasionally cause inner ear trauma or toxicity, leading to mixed hearing loss.

Extensive Spread of Infections: Infections such as bacterial meningitis or otitis media may affect both middle and inner ear structures, causing combined hearing loss.

Congenital Syndromes with Anatomical Anomalies: Some congenital syndromes involve malformations in both outer/middle and inner ear structures, leading to mixed hearing loss.

📞 If you are seeking professional support for hearing loss in Cyprus, contact İskele Hearing Center today. For more information or to book an appointment, feel free to reach out to us.