What is the correct unit of measurement for the X-axis of an audiogram?

The correct unit of measurement for the X-axis of an audiogram is Hertz (Hz), which represents frequency. In an audiogram, the X-axis typically illustrates the frequency range, indicating how pitch variations affect hearing. Frequencies are measured in Hertz, and they are presented usually in a logarithmic scale, encompassing low frequencies (such as bass sounds) on the left and high frequencies (like treble sounds) on the right.

The measurement of decibels (dB) is actually used for the Y-axis to represent the intensity or loudness of sounds, quantified as sound pressure levels. Millimeters are a physical measurement for length, not applicable to frequency or loudness in audiograms. Percentages do not provide the pertinent data required for depicting auditory frequency or loudness levels in a standard audiogram format. Therefore, Hertz is the appropriate unit to measure frequency, making it the correct answer in this context.