Several options exist to diagnose conductive hearing loss. An otoscopy can rule out an injured eardrum, foreign bodies in the ear canal (such as ear wax), and middle ear effusion.
During the Weber test, a tuning fork is struck and placed on the crown of the head. A person with normal hearing should be able to perceive the sound equally in both ears. If a patient has conductive hearing loss, the sound travels to the impaired ear.
During the Rinne test, a tuning fork is struck and placed on the mastoid bone behind the ear and the patient signals when he can no longer hear the tone. Then the (still oscillating) tuning fork is moved near the ear canal and the patient again signals when he can no longer hear the tone. In cases of normal hearing, the mastoid bone conduction sound is heard for half the amount of time as the second sound. If a patient has conductive hearing loss, mastoid bone conduction sound is heard for a longer or equal amount of time than the second sound.
A tympanogram measures the mobility of the eardrum. If the middle ear has the same pressure as the external ear canal, the eardrum will oscillate normally. If there is a difference in pressure, the oscillation behavior and thus the sound conduction will change. This examination detects whether there is an increased pressure (e.g. in the event of secretory otitis media) or a reduced pressure (e.g. in the event of impaired ventilation) in the tympanic cavity, which effectively localizes the cause of conductive hearing loss.
Pure-tone audiometry distinguishes thresholds between impaired bone and air conduction, and differentiates between sensorineural and labyrinthine hearing loss. Defects in the labyrinth, which can lead to conductive hearing loss, cause the air conductance curve to be at higher decibel values than bone conductance. In other words, aid conduction requires a significantly louder tone to achieve a degree of perception comparable with bone conduction. When this happens, sound is conducted less efficiently via the airway.