Understanding Audiometry and Audiograms
Introduction to Audiometry
Overview of Audiometry
- Tom introduces the topic of audiometry, explaining that it involves objectively testing a patient's hearing through various tones and volumes.
- Air conduction is tested using headphones, while bone conduction is assessed with an oscillator that delivers sounds directly to the skull.
Understanding Audiograms
- Audiograms are charts used to document the volume at which patients can hear different tones, with frequency in hertz plotted on the x-axis and volume in decibels on the y-axis.
- The chart indicates that lower positions represent louder sounds (higher decibels), while higher positions indicate more sensitive hearing (lower decibels).
Testing Hearing Levels
- Hearing tests establish the quietest volume at which a patient can hear each frequency; results are marked on the audiogram accordingly.
- Normal hearing is indicated by readings between 0 and 20 decibels. Sensorineural hearing loss shows both air and bone conduction readings below this threshold.
Types of Hearing Loss
- In conductive hearing loss, bone conduction remains normal (0–20 dB), but air conduction readings exceed 20 dB due to issues along the ear's pathway.
- Mixed hearing loss presents both air and bone conduction readings above 20 dB, with a notable difference of over 15 dB favoring bone conduction.