move and transduction occurs. The organ of Corti fires, and these impulses are transmitted to the brain via
the auditory nerve.
One way to remember amplitude and frequency is to imagine you are watching waves go by. Frequency is how frequently the
waves come by. If they speed by quickly, the waves are high in frequency. Amplitude is how tall the waves are. The taller the
waves, the more energy and the louder the noise.Pitch Theories
The description of the hearing process above explains how we hear in general, but how do we hear
different pitches or tones? As with color vision, two different theories describe the two processes
involved in hearing pitch: place theory and frequency theory.
PLACE THEORY
Place theory holds that the hair cells in the cochlea respond to different frequencies of sound based on
where they are located in the cochlea. Some bend in response to high pitches and some to low. We sense
pitch because the hair cells move in different places in the cochlea.
Figure 4.2. Cross section of the ear.FREQUENCY THEORY
Research demonstrates that place theory accurately describes how hair cells sense the upper range of
pitches but not the lower tones. Lower tones are sensed by the rate at which the cells fire. We sense pitch
because the hair cells fire at different rates (frequencies) in the cochlea.