Audiogram

The purpose of an audiological assessment is to quantify and qualify hearing in terms of the degree of hearing loss, the type of hearing loss and the configuration of the hearing loss. The audiogram is a graph showing the results of the hearing test. With regard to the type of hearing loss, the audiologist is looking for information that suggests the point in the auditory system where the loss is occurring.

The hearing loss may be conductive (a temporary or permanent hearing loss typically due to abnormal conditions of the outer and or middle ear), sensorineural (typically a permanent hearing loss due to disease, trauma, or inherited conditions affecting the nerve cells in the cochlea, the inner ear, or the eighth cranial nerve), or mixed (a combination of conductive and sensorineural components).

As the audiologist tests your child’s hearing, the results are recorded on the audiogram. At each frequency or pitch tested, the “O” represents the softest tone you can hear in your right ear and the “X” denotes the softest tone you can hear in your left ear. The “S” corresponds to sounds presented through the speakers.

If the “X’s” and “O’s” or “S’s” all fall in the -10 dB to 25 dB range, your hearing lies in the normal range. The following chart describes the effects on listening with the varying degrees of hearing loss. The degree of hearing loss is measured in terms of decibel level, not percentage.

Pitch or frequency

Each line from left to right represents a pitch or frequency in Hertz (Hz) starting with the lowest pitches on the left side to the very highest frequencies tested on the right side. The range of frequencies tested by the audiologist is typically from 125Hz to 8000Hz. If you are familiar with a piano keyboard, with the low notes to the left and the high notes at the right end, the audiogram is similar. 250Hz on the audiogram is the same as the “middle C” key on the piano.

Examples of sounds in everyday life that would be considered low frequency are: bass drum, tuba and vowel sounds such as “oo” in “who.”

Examples of sounds in everyday life that would be considered high frequency are:  a bird chirping, a triangle playing, consonant sounds, such as “s” in “sun.”

If we were to compare a flute playing and a tuba playing, we’d say the flue was primarily high frequency (high pitches), and the tuba was playing at “low frequency” (low pitches). If we were to compare the sound of “f” as in “fly” to the sound of “m” as in “moon”, we’d say the “f” was primarily high frequency (high pitch) and the “m” was primarily low frequency (low pitch).

Loudness or intensity

Each line on the audiogram from top to bottom represents loudness or intensity in units of decibels (dB). Lines at the top of the chart (small numbers starting at minus 10 dB and 0 dB) represent soft sounds. Lines at the bottom of the chart represent very loud sounds. Examples of sounds in everyday life that would be considered “soft” are:  a clock ticking, whispering, or the consonant sound of “t” in the word “too.”

Examples of sounds in everyday life that would be considered “loud” are:  a lawnmower, a car horn, or the vowel sound “o” as in the word “poke.”

If we were to compare the sound of “s” as in “spot” to the sound “ah” in “spot” we’d say the “s” was “soft” in comparison to the vowel “ah.”

If we were to compare “normal conversational loudness level” (typically 60 dB) to “whispering” (typically 30 dB), we’d say that whispering is soft and conversation is loud.

The aspects of the configuration of the hearing loss are bilateral (both ears) versus unilateral (one ear) hearing loss; (different degree of hearing loss in each ear); high-frequency versus low frequency hearing loss; flat versus sloping versus precipitous hearing loss; progressive versus sudden hearing loss; and stable versus fluctuating hearing loss.