The hearing curves show a significant dip in the range 2000-5000 Hz with a peak sensitivity around 3500 -4000 Hz. This is associated with the resonance of the auditory canal. There is another enhanced sensitivity region at about 13,500 Hz which may be associated with the third harmonic resonance of the auditory canal. The high sensitivity region at 2-5kHz is very important for the understanding of speech.

The maximum sensitivity regions of human hearing can be modeled as closed tube resonances of the auditory canal. The observed peak at about 3700 Hz at body temperature corresponds to a tube length of 2.4 cm. The higher frequency sensitivity peak is at about 13 kHz which is somewhat above the calculated 3rd harmonic of a closed cylinder.