Understanding the Audiogram and Hearing

Sounds that we hear have several characteristics. Imagine a guitar string plucked to make a note. The guitar string vibrates. You can see it, feel it and hear it. That guitar string is vibrating back and forth at a certain speed. A thick string will vibrate at a slower frequency and be heard as a lower pitched sound. A thinner more tightly tuned string will vibrate with a faster frequency and be heard as a higher pitched sound.

 

If you pluck the guitar string harder, it will vibrate at the same speed, but with more force or intensity, and the note will sound louder to you.

Frequency and Intensity are the two characteristics of sound that are used to measure hearing. Frequency is measured in Hz or cycles per second. A 250Hz sound is a low frequency sound, 1000Hz is a mid-frequency sound and 2000-8000Hz are high frequency sounds. 500Hz is similar in pitch to middle C on a piano.

 
 
 
 

Intensity is measured in decibels dBHL. 0-15dBHL are soft sounds, barely audible. 90-100dBHL are very loud, possibly painful sounds for most listeners.

 An Audiometer produces specific frequency tones at controlled intensities and delivers them to the child via some kind of earphone. The softest sounds at each frequency to which your child responds are graphed for each ear on an audiogram.

Hearing loss is present when your child’s hearing at any frequency exceeds 20dBHL. Mild hearing losses : 25-40dB, Moderate: 45-60dB, Moderately Severe: 60-75dB, Severe: 75-90dB, Profound: 90db and above.  The more severe the hearing loss, the less speech your child can hear and learn.  

 

 The Audiogram on the left displays  responses for normal hearing. Both the right ear (red) and the left ear (blue)are well above 15dBHL for each frequency.  

For more information check this EXCELLENT site. RaisingDeafKids.org

This site is the resource for this audiogram. and displays examples of audiograms for different degrees of hearing loss.

There are short audio clips of what each degree of hearing loss might sound like.  

Note: audio clips are on the bottom of the web page

 

                                  

This is a “common sounds audiogram” It shows the typical frequencies and intensities of both some environmental sounds and speech sounds. Plotting your child’s hearing results on this graph will give you a basic idea of what speech sounds and environmental sounds your child is hearing.