The numbers that run along the top, or horizontal axis, of the audiogram represent frequency.

Frequency (also known as "pitch") is measured in Hertz (Hz). The higher the number, the higher the pitch of the tone; the lower the number, the lower the pitch of the tone.

Audiograms typically contain frequencies from 250 Hz to 8000 Hz, in increments that double from left to right.

Other frequencies may also be tested and marked on an audiogram. As 6000 Hz may be commonly checked in addition to the standard frequencies, it is often included on the audiogram.