Hearing Loss Types, Audiometry & Hearing Aids Guide

Hearing loss means a person cannot hear sounds as well as someone with normal hearing. It is measured in decibels (dB): the higher the number, the louder a sound must be before it is noticed. A whisper is about 20 dB and normal conversation about 60 dB. Hearing loss can affect one ear or both, and ranges from mild to profound.

In children, even mild loss can delay speech and language, harming school performance for life. In adults it causes social withdrawal and faster cognitive decline. The good news: most causes are treatable, and early testing with audiometry plus the right hearing aid can restore communication almost fully.

Key Concepts

• Conductive hearing loss: the problem is in the outer or middle ear — earwax blockage, middle-ear fluid, a perforated eardrum or otosclerosis. Sound cannot reach the inner ear, but the nerve works fine. Often curable with medicine or surgery.
• Sensorineural hearing loss: the problem is in the cochlea or auditory nerve — ageing (presbycusis), loud noise, ototoxic drugs like gentamicin, or meningitis. Usually permanent; managed with hearing aids or cochlear implants.
• Mixed hearing loss: conductive and sensorineural loss in the same ear.
• Audiogram: the graph from pure-tone audiometry, plotting the softest heard tone at each frequency (250–8000 Hz). Air conduction uses headphones; bone conduction uses a skull vibrator. An air-bone gap over 10 dB signals a conductive component.
• Tuning-fork tests: Rinne test — normally air beats bone (positive); in conductive loss bone beats air (negative). Weber test — sound shifts to the poorer ear in conductive loss, to the better ear in sensorineural loss.

Formulas

• Decibel: dB = 10 × log10(I / I0), where I0 is the faintest audible sound. Because of the logarithm, 20 dB is 100 times more intense than 0 dB.
• Pure-tone average: PTA = (threshold at 500 Hz + 1000 Hz + 2000 Hz) ÷ 3.
• Severity: normal −10 to 25 dB, mild 26–40, moderate 41–55, moderately severe 56–70, severe 71–90, profound above 90 dB.

Worked Example

1. Audiometry of the right ear: air conduction 55, 60, 65 dB at 500/1000/2000 Hz; bone conduction 10, 15, 15 dB.
2. PTA = (55 + 60 + 65) ÷ 3 = 60 dB → moderately severe (56–70 band).
3. Air-bone gap at 1000 Hz = 60 − 15 = 45 dB, far above the 10 dB cutoff, so a conductive element exists. Bone conduction averages ~13 dB (normal), so the nerve is healthy → pure conductive loss, moderately severe. The Rinne test would be negative on this ear; ENT referral follows for possible surgery or a hearing aid.

Common Misconceptions

• Myth: Hearing aids restore normal hearing. Fact: they amplify sound, but clarity depends on a healthy nerve; in sensorineural loss speech may still sound distorted.
• Myth: Only old people get hearing loss. Fact: newborns can be born with it and children get it from ear infections — hence newborn screening.
• Myth: Cotton buds safely clean ears. Fact: they push wax deeper and can perforate the eardrum; persistent blockage needs a doctor.

Real-World Applications

• Newborn screening: OAE and ABR tests catch congenital deafness in the first days of life, when cochlear implants work best.
• School and occupational programs: routine audiometry finds loss in children and noise-exposed workers.
• Hearing-aid fitting: audiologists program digital aids (behind-the-ear, in-the-ear, in-canal) from the patient's exact audiogram.

Hearing loss is conductive, sensorineural or mixed, and audiometry with the pure-tone average tells exactly which type and how severe it is. Most conductive causes are curable, and modern hearing aids or implants manage the rest — so early testing means nobody needs to live in silence.