Final answer:
A gross hearing assessment can be carried out using tuning forks. The Rinne test is used to distinguish between conductive and sensorineural hearing loss, while the Weber test can differentiate between unilateral conductive and sensorineural hearing loss. The tests involve placing a tuning fork on the mastoid process and at the top of the skull to assess how sound is conducted through the temporal bone and air.
Step-by-step explanation:
Hearing is tested by using a tuning fork in a couple of different ways. The Rinne test involves using a tuning fork to distinguish between conductive hearing and sensorineural hearing. Conductive hearing relies on vibrations being conducted through the ossicles of the middle ear. Sensorineural hearing is the transmission of sound stimuli through the neural components of the inner ear and cranial nerve. A vibrating tuning fork is placed on the mastoid process and the patient indicates when the sound produced from this is no longer present. Then the fork is immediately moved to just next to the ear canal so the sound travels through the air. If the sound is not heard through the ear, meaning the sound is conducted better through the temporal bone than through the ossicles, a conductive hearing deficit is present.
The Weber test also uses a tuning fork to differentiate between conductive versus sensorineural hearing loss. In this test, the tuning fork is placed at the top of the skull, and the sound of the tuning fork reaches both inner ears by travelling through bone. In a healthy patient, the sound would appear equally loud in both ears. With unilateral conductive hearing loss, however, the tuning fork sounds louder in the ear with hearing loss. This is because the sound of the tuning fork has to compete with background noise coming from the outer ear, but in conductive hearing loss, the background noise is blocked in the damaged ear, allowing the tuning fork to sound relatively louder in that ear.
With unilateral sensorineural hearing loss, however, damage to the cochlea or associated nervous tissue means that the tuning fork sounds quieter in that ear.