Audiograms

Tympanogram interpretation

This week we will complete the ear evaluation and specifically look at AUDIOGRAMS.  They are a very useful tool to determine if a patient has conductive or sensorineural hearing deficit, and to what extent. 

The frequency (pitch) is plotted on the x-axis, and the intensity on the y-axis. 

• O Air Conduction
• < Bone Conduction
• [ Masked Bone Conduction--Masking presents a constant noise to the nontest ear to prevent ear crossover from the test ear

Normal hearing is defined as 15dB or better. 

The test involves assessing air conduction (o) and bone conduction 

Air conduction assesses hearing sensitivity when the signal is transmitted through the outer, middle, and inner ear and then through the brain. 

Bone conduction assesses hearing sensitivity when the signal is transmitted through the bones of the skull to the cochlea and through the auditory pathways of the brain. 

1) Conductive hearing loss- Nml bone conduction, air conduction poorer than normal by at least 10dB, i.e. otitis media with/without effusion, ear wax

2) Sensorineural hearing loss- both air and bone conduction poorer than normal, and within 10dB of each other; secondary to cochlear abnormality and/or abnormality of auditory nerve or central auditory pathways i.e. cochlear damage (i.e. noise induced), CN8 damage

3) Mixed hearing loss- loss of both conductive and sensorineural components- Pure tone air conduction thresholds are poorer than bone conduction thresholds by more than 10dB and  bone conduction thresholds are less than 25 dB

Get used to and comfortable looking at these- they are loved by the boards. 

How is it done?

Play Audiometry

• ages 2.5 ages 2.5-4yrs 4yrs
• Child is conditioned to put a peg in a peg board when stimulus tone is heard when stimulus tone is heard
• advantage: ear specific results
• Limitations: attention span of child may limit the amount of information obtained amount of information obtained

Conventional Audiometry

• 4yrs to adults 4yrs to adults
• Patient is instructed to raise his or her hand when stimulus is heard stimulus is heard