Do you know what a Pure Tone Average is? Everybody knows what 20/20 means. 120/80. 3.5–1. If optimal eyesight, blood pressure, and cholesterol ratios are considered common knowledge, why then are so few familiar with Pure Tone Average or PTA? It starts by understanding exactly what it means. Let us explain.
Functional Hearing, or peripheral hearing if you prefer, is usually tested for each ear separately, under clinically calibrated headphones. Different frequencies (represented in Hertz or Hz) are tested at different intensity levels (represented in decibels or dB). The healthy human ear can typically detect between 20 and 20 000 Hz with an intensity range of 0 to 120 dB. With our current daily life activities, hearing in humans is mainly used for speech understanding.
Speech sound components can be represented from 125-8000 Hz depending on the speaker. Therefore, hearing testing usually concentrates on the frequencies represented in male and female human voices, namely 250 – 8000 Hz. The number of select frequencies tested can vary upon the age of the person tested, the reason for the test, and the time allotted for testing.
A Pure Tone Average (PTA) refers to the average of hearing threshold levels at a set of specified frequencies: typically 500, 1000, 2000 and 4000 Hz. This value gives a snapshot of an individual’s hearing level in each ear. As speech sounds are more densely represented in the mid frequencies, the outlying frequencies are not included in the PTA calculation to allow for more consistent comparisons. If your PTA is <25 dB, your overall hearing would be considered to be within normal limits. With a PTA of 95 dB, your hearing would be considered in the profound range. PTA is also helpful when comparing one ear to the other, to determine if you have a ‘better hearing’ side.
SHOEBOX Audiometry automatically calculates PTA on each ear tested, so you don’t have to. Taking appropriate hearing protection measures, having a record of your baseline audiogram on file, and reporting any suspected changes in hearing will help keep your PTA in the best range possible for decades to come.