What is an Audiogram?

An audiogram is a graph where your test responses are charted.  It provides a picture of your hearing sensitivity for each ear at specific tones.  

The inner ear is designed similar to that of a piano.  The sensory cells of the inner ear are each finely tuned to a particular tone (frequency in Hertz [Hz]), like a key on a piano keyboard.  The audiogram charts these frequencies along the bottom of the graph.  Typically the frequencies run left to right, 250Hz to 8000Hz, with 250Hz being a very low-pitched tone, 8000Hz being a very high-pitched tone.

The volume of the tones is measured in decibels (dB). The presentation level of these frequencies is charted vertically along the side of the graph.  A normal hearing ear would detect the tones in the decibel range of 0 – 20 dB, which is around the top of the graph.   When the frequencies have to be presented louder than 20 dB in order for an ear to detect it, a hearing loss for this particular tone is indicated, and the results would be charted lower on the graph. 

If there is a hearing loss evident, it will be described in its degree of severity.  A mild degree of hearing loss will fall in the range of 25-40 dB.  Profound hearing loss would be at the bottom of the graph, in the range of 90+dB.  A mild-to-profound hearing loss would be one that was mild in the low frequency range (left side of audiogram) and gradually or sharply dropped down into the profound range for the highest frequencies (right side).

The most important sounds for us are speech sounds.  We need to hear all the speech sounds in order to understand speech well.  When we are in noise, hearing all the speech sounds is especially important.  Slight hearing loss may not be very bothersome as long as the environment is quiet. The most important frequency for speech understanding is 2000Hz.  This frequency provides 33% of the consonants we need to understand words.  If you have good hearing in the low frequencies (left side of the graph) but have hearing loss in the mid to high frequencies, you will hear vowel sounds well but may miss hearing the consonants, causing you to think people are always mumbling.  This is a common complaint among people with hearing loss.  

For a good visual explanation of the audiogram see www.earinfo.com/howread1.html.