Audiogram
Definition
Audiogram is a graphical representation of audiometric studies performed to detect hearing loss
Audiometry
Audiometry is the single most important diagnostic instrument to detect hearing loss.
Two kinds of audiometric testing :
Pure tone audiometry : sound stimulus : pure or musical tone
Speech audiometry : sound stimulus : spoken word
In pure tone audiometry the louder the tone before the patient perceives it the greater the hearing loss
In speech audiometry the ability to hear and discriminate sounds and words.
The audiometrist performs the test
The patient wears earphones and sits in a sound proof room and signals when he
hears a tone
Air conduction and bone conduction (applying the stimulus to the mastoid bone) both are tested
Responses are plotted on graph (audiogram)
Important Characteristics in evaluation
Frequency
Pitch
Intensity
Normal Human Range
Range of frequency perceived 20 to 20,000 Hz.
Speech range of frequencies 500 to 2000 Hz.
A tone with 100 Hz - low pitch
A tone with 10,000 Hz - high pitch
The unit for measuring loudness is the decibel (dB),
Hearing loss is measured in decibels
Sounds louder than 80 dB - harsh to human ear and damaging to the inner ear.
