Definition

Mixed hearing loss is a condition characterized by the simultaneous occurrence of conductive hearing loss and sensorineural hearing loss, resulting in mild to severe hearing loss. The ear comprises three parts: the outer ear, the middle ear, and the inner ear. Conductive hearing loss occurs when sound cannot be transmitted through the outer and middle ear to the inner ear. This type of hearing loss is caused by obstructions in the ear that prevent sound from entering the inner ear. Sensorineural hearing loss, also known as neural hearing loss, occurs when there is damage to the hair cells in the inner ear, or problems with the auditory nervous system, preventing sound from being transmitted to the brain.

Sometimes, conductive hearing loss occurs together with sensorineural hearing loss. In mixed hearing loss, damage to both the outer and middle ear impedes sound transmission to the inner ear and damage to the inner ear (cochlea) or auditory nerve.

Causes

Any cause of conductive or sensorineural hearing loss can lead to mixed hearing loss. For instance, someone working in a noisy environment might experience sensorineural hearing loss due to prolonged exposure to loud sounds. If this person also has earwax blocking their ear canal, they may also develop conductive hearing loss. Combining these problems results in mixed hearing loss, causing more severe impairment than either condition on its own. Mixed hearing loss can also occur in people with ear injuries.

Causes of conductive hearing loss include:

• Fluid buildup in the middle ear due to colds or allergies.
• Outer or middle ear infections, with external ear infections commonly called swimmer's ear.
• Abnormalities in the eustachian tube, a tract that connects the middle ear and nose. This can cause fluid to accumulate in the middle ear if the tube does not function properly.
• Damage to the eardrum, such as perforations.
• Benign tumours (non-cancerous mass) that block the outer or middle ear.
• Earwax accumulation that obstructs the ear canal.
• Foreign objects in the ear canal, often occurring in children who insert items like pebbles, nuts, or beads into their ears.
• Congenital abnormalities of the outer or middle ear, such as being born without an outer ear, having an abnormal ear canal shape, or bone deformities in the middle ear.

Causes of sensorineural hearing loss include:

• Normal aging process
• Exposure to loud noises or explosions, often from workplaces or loud music.
• Medications that can impair hearing (ototoxic).
• Genetic factors or infections during pregnancy. Neurological hearing loss in children is often due to genetic disorders or infections transmitted from mother to fetus, such as toxoplasma, rubella, or herpes.
• Head injuries.
• Congenital disorders of the inner ear.
• Other less common causes include heart disease, diabetes, infections such as mumps, Meniere's disease, and autoimmune diseases.

Symptoms

Mixed hearing loss can manifest in one or both ears, presenting a combination of symptoms from both conductive and sensorineural hearing loss.

Symptoms of sensorineural hearing loss:

• Conversations may sound unclear, creating a feeling of hearing but not understanding the content.
• Difficulty in following conversations when multiple people are speaking simultaneously.
• Persistent ringing in the ears (tinnitus).
• Hearing difficulty in noisy environments, such as stations, construction sites, malls, and other crowded places.
• Difficulty in hearing high-pitched sounds, often women's and children's voices.
• Sounds that are usually loud may seem quieter or muffled.
• A sense of imbalance.
• Difficulty in hearing soft sounds.
• Loud sounds may appear unclear or distorted.

Problems in conductive hearing loss are primarily with sound volume; the symptoms will often improve by increasing the volume. Other symptoms of conductive hearing loss are:

• Easier to hear from one ear compared to the other
• Ear pain
• Sensation of fullness in the ears
• Difficulty in telephone conversations
• Fluid discharge from the ear canal
• Perception that one's own voice is louder or different

Diagnosis

Diagnosing mixed hearing loss involves a comprehensive examination by an otolaryngologist, including an evaluation of the ears, nose, and throat. The doctor will determine the presence of conductive hearing loss in patients and identify its cause to select appropriate therapy. An audiological assessment is conducted to assess sensorineural hearing loss in detail and to determine the need for hearing aids if necessary.

Management

Conductive hearing loss can often be treated with medication or surgical procedures, while sensorineural hearing loss, which is typically permanent, requires hearing aids as the primary treatment. Therefore, treatment for mixed hearing loss generally involves a combination of medication, surgery, and hearing aids. In some cases, implants or specialized hearing aids may be necessary.

• Treatments for conductive hearing loss include medications, earwax removal, and surgical procedures, depending on the underlying cause. It is advisable to address conductive hearing loss first, which ensures better results when using hearing aids afterwards.
• Hearing aids. These devices help individuals with hearing loss by amplifying sounds and improving the perception of speech and other sounds, though they do not restore normal hearing. Hearing aids come in various types and sizes, including modern digital versions with small sizes that offer improved functionality to meet each person's hearing needs. They are worn inside or behind the ears. Many researches have shown that the use of hearing aids can improve quality of life. In general, hearing aids will keep improving as science and technology advances.  The development of hearing aids occurred in such a way as to more closely resemble normal human hearing. A hearing aid should be chosen in consultation with a specialist to meet individual needs best.
• Cochlear implants. The implants can deliver sound directly to the brain via the auditory nerve, making it possible for people with inner ear cell damage and severe hearing loss to hear. This treatment can be chosen for severe sensorineural hearing loss that doesn't improve with hearing aids. Cochlear implants are installed surgically, usually under general anesthesia.

Complications

Hearing loss can significantly impact a person's quality of life and mental health. Individuals with hearing loss may struggle to understand others, which can increase anxiety and lead to depression.

Prevention

The most preventable cause of hearing loss is exposure to loud noise. Sounds exceeding 85 decibels can damage the hair cells in the inner ear that convert sound into signals to the brain. Measures to prevent noise-induced hearing loss include:

• Reducing exposure to loud noise
• Avoid listening to music at high volumes through headphones or earbuds
• Using earplugs or ear protectors during activities involving loud sounds or when the noise level is above 85 decibels

When to see a doctor?

You should consult a doctor if you suspect a hearing problem to undergo a hearing test. Additionally, seek medical advice if you experience symptoms such as ear pain, a feeling of fullness in the ears, ringing, or a sudden change in hearing. These symptoms may indicate preventable hearing loss.

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