According to the Singapore Ministry of Health, the rate of hearing loss among adults ages 18–74 has increased from 1.3% in 2013 to 9.2% in 2023. This increase has created a heightened concern about the country's hearing loss, primarily linked to ageing and lifestyle factors.
Hearing loss can range from mild difficulty hearing in noisy environments to complete deafness, significantly impacting communication, social interaction, and overall quality of life. Two common types of hearing loss are high-frequency hearing loss and low-frequency hearing loss. The former constitutes the majority of hearing loss cases.
What Are Low-Frequency and High-Frequency Hearing Losses?
Hearing loss may be categorised into two groups depending on the types of sounds the person has trouble hearing.
Low-Frequency Hearing Loss
Low-frequency hearing loss is characterised by the inability to perceive sounds with lower pitches (≤ 2,000 Hz). It can manifest as difficulty understanding male voices, appreciating the deep tones of musical instruments like bass guitars or cellos, or even hearing the rumble of thunder. Individuals with low-frequency hearing loss may also experience difficulties in following conversations and understanding telephone calls.
Low-frequency hearing loss can be further categorised into two main types depending on the specific part of the ear that is damaged:
- Sensorineural Low-Frequency Hearing Loss: This type arises from damage to the delicate hair cells within the inner ear (cochlea), the auditory nerve that transmits sound signals to the brain, or the cochlea itself.
- Conductive Low-Frequency Hearing Loss: This occurs when there is an obstruction or dysfunction within the outer ear (ear canal), the middle ear (eardrum, ossicles), or the pathway through which sound waves travel to reach the inner ear.
High-Frequency Hearing Loss
This is a more common type of hearing loss, characterised by difficulty perceiving higher-pitched sounds (2,000–8,000 Hz). Individuals may struggle to understand women's voices, especially those of children, and may have trouble hearing birdsong, doorbells, or words that start and end with "s," "h," and "f."
What Are the Causes?
Both low-frequency and high-frequency hearing loss have distinct sets of causes and risk factors.
Causes of Low-Frequency Hearing Loss
Low-frequency hearing loss can arise from various factors, including:
- Genetic Predisposition - Certain inherited conditions can predispose individuals to specific types of hearing loss, including low-frequency loss.
- Wolfram Syndrome: This rare genetic disorder, caused by mutations in the WFS1 gene, manifests with a combination of low-frequency sensorineural hearing loss, diabetes mellitus, diabetes insipidus, and optic atrophy.
- Mondini Dysplasia: This congenital malformation of the inner ear is often associated with low-frequency sensorineural hearing loss.
- Middle Ear Dysfunction - Issues within the middle ear, such as fluid buildup or infections, can interfere with the transmission of sound waves, potentially leading to low-frequency hearing impairment.
- Otitis Media with Effusion (OME): Fluid accumulation in the middle ear, often due to unresolved infections or Eustachian tube blockage (e.g., from allergies), can interfere with sound transmission.
- Otosclerosis: This condition involves abnormal bone growth around the stapes bone in the middle ear, leading to conductive hearing loss, particularly affecting lower frequencies.
Causes of High-Frequency Hearing Loss
High-frequency hearing loss can arise from various factors, including:
- Noise Exposure: Prolonged or intense exposure to loud sounds (e.g., concerts, construction, industrial machinery) can damage the delicate hair cells in the inner ear, leading to permanent hearing loss, particularly in the higher frequencies.
- Ageing (Presbycusis): As we age, the natural wear and tear on the auditory system leads to a gradual decline in hearing sensitivity, often beginning with high-frequency sounds.
- Genetic Predisposition: A family history of hearing loss increases the risk of developing hearing problems, including high-frequency loss.
- Ototoxic Medications: Certain medications, such as some antibiotics and chemotherapy drugs, can have a toxic effect on the inner ear, resulting in hearing loss, including high-frequency loss.
Meniere’s disease, an inner ear disorder, can also cause low- or high-frequency hearing loss. It is characterised by episodes of fluctuating hearing loss, tinnitus, and vertigo. These episodes can vary in duration, from minutes to several hours. Meniere’s disease results from an abnormal buildup of fluid within the inner ear, although the exact mechanism remains unclear.
Diagnostic Procedures for Low- and High-Frequency Hearing Loss
Diagnosing low- and high-frequency hearing loss typically begins with a comprehensive patient evaluation. An ENT specialist will conduct a thorough medical history and symptom assessment. This includes inquiring about the onset and progression of hearing loss, specific difficulties experienced, and any associated symptoms like tinnitus or dizziness.
In addition, diagnostic tests will be performed, which may include:
- Audiometry: A key test in hearing evaluation, this measures the patient's ability to hear different sounds at various frequencies and intensities.
- Speech Recognition Test: This hearing test evaluates the patient’s ability to hear in low- and high-noise environments.
- Tympanometry: This test measures the eardrum's movement in response to changes in air pressure within the ear canal. It helps identify middle ear problems like fluid buildup or eardrum perforation.
- Imaging Tests: A CT scan or MRI can provide detailed images of the ear structures, helping to identify abnormalities like tumours, bone growths, or structural malformations.
Based on the results of these assessments, the ENT specialist can determine the type, severity, and cause of hearing loss and recommend appropriate treatment options.
Treatment Options for Low- and High-Frequency Hearing Loss
The treatment approach for both low- and high-frequency hearing loss depends entirely on the underlying cause.
- Medications: Antibiotics may be given to manage hearing loss caused by infections. Doctors may also prescribe alternative medications if certain ones are contributing to the hearing loss.
- Hearing Aids: Hearing aids are typically the most effective treatment option for irreversible hearing loss. Before being fitted for a hearing aid, a comprehensive hearing test is necessary to determine the type and severity of hearing loss.
- Implants: Cochlear implants and active middle ear implants may be recommended for individuals with sensorineural hearing loss who do not benefit from hearing aids.
- Surgery: Certain types of hearing loss, such as those caused by otosclerosis or otitis media with effusion, may be treated with surgical procedures like stapedectomy or tympanostomy tube placement to improve hearing.
- Blood Patch Procedure: When low cerebrospinal fluid pressure after spinal anaesthesia leads to low-frequency hearing loss, a blood patch procedure can help restore normal hearing by sealing the leak and stabilising fluid pressure.
Hearing loss related to Meniere’s disease may be more challenging to treat due to its fluctuating nature. Hearing loss may initially come and go but often progresses over time. Treatment focuses on managing symptoms such as reducing salt intake, limiting caffeine and alcohol consumption, and maintaining a healthy weight.
How to Prevent Low- and High-Frequency Hearing Loss
Hearing loss, whether low-frequency or high-frequency, can significantly impact quality of life. While some factors are beyond our control, proactive measures can significantly reduce the risk:
- Hearing Tests: Regular hearing screenings, especially for high-risk individuals (the elderly, those with a family history of hearing loss, and those exposed to loud noise), can identify early signs of hearing loss and allow for timely intervention.
- Safe Listening Practices: Minimise exposure to loud noises whenever possible. Utilise earplugs or earmuffs while using power tools and in noisy environments like concerts and construction sites. It is also best to take frequent breaks from listening to loud music through headphones and choose noise-cancelling headphones when available.
- Prompt Treatment: Address ear infections, allergies, and other ENT conditions promptly to prevent complications that can affect hearing. Schedule regular checkups with an ENT specialist to monitor and manage any underlying conditions.
If you are experiencing symptoms of hearing loss, consult an ENT specialist for a detailed assessment. You may give us a call at 6738 1616 to book a consultation.
