Airconduction

Air conduction refers to the passage of acoustic energy through the air from a sound source to the inner ear. In clinical audiology, air-conduction testing uses headphones or insert earphones to deliver pure tones and speech, allowing assessment of a person’s hearing sensitivity across standard frequencies, typically from 250 to 8000 Hz.

The acoustic signal travels through the external auditory canal to the tympanic membrane (eardrum), causing it to vibrate. These vibrations are transmitted via the middle-ear ossicular chain (malleus, incus, stapes) to the cochlea in the inner ear, where mechanical energy is converted into neural signals by hair cells. Air conduction thresholds thus reflect the integrity of the outer ear, middle ear, inner ear, and the neural pathways up to the auditory cortex.

Air-conduction testing is routinely compared with bone-conduction testing, which bypasses the outer and middle ear by delivering vibrations directly to the cochlea through the skull. The comparison helps classify hearing loss into conductive (impaired air conduction with normal bone conduction and a significant air-bone gap), sensorineural (reduced air and bone conduction with no significant gap), or mixed loss (both reduced with a significant gap).

Results are expressed in decibels hearing level (dB HL). Testing guides diagnosis and management, including medical or surgical treatment for middle-ear disease or fitting of amplification devices such as hearing aids, as well as monitoring over time.