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How does frequency determine the pitch that people hear?

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Watch a suspended vibrating spring to learn about the propagation of sound waves — sound Learn about the propagation of sound waves from a point source by observing the motion of a suspended vibrating spring.

Frequency is the physical property of a sound wave defined by the number of wavelengths that pass a specific point per second, typically measured in hertz. Humans perceive this physical property physiologically as pitch, where a higher frequency corresponds to a higher perceived pitch and a lower frequency corresponds to a lower perceived pitch.12

The human ear distinguishes pitch through the basilar membrane within the cochlea. Because the membrane varies in stiffness, width, and mass along its length, different frequencies cause different regions to vibrate most vigorously. High-frequency sounds stimulate the basal end of the membrane, while low-frequency sounds affect the apical end. The brain identifies the pitch by recognizing which specific group of nerve fibres is activated by these vibrations. For lower frequencies (up to approximately 3,000 hertz), the rate of nerve stimulation also serves as an important indicator of pitch to the brain.3