Place theory is a

theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may ...

hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is audit ...

that states that our perception of sound depends on where each component

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

produces vibrations along the

basilar membrane The basilar membrane is a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani. The basilar membrane moves up and down ...

. By this theory, the pitch of a sound, such as a human voice or a musical tone, is determined by the places where the membrane vibrates, based on frequencies corresponding to the

tonotopic In physiology, tonotopy (from Greek tono = frequency and topos = place) is the spatial arrangement of where sounds of different frequency are processed in the brain. Tones close to each other in terms of frequency are represented in topologically ...

organization of the primary auditory neurons. More generally, schemes that base attributes of auditory perception on the neural firing rate as a function of place are known as rate–place schemes. The main alternative to the place theory is the

temporal theory The temporal theory of hearing states that human perception of sound depends on temporal patterns with which neurons respond to sound in the cochlea. Therefore, in this theory, the pitch of a pure tone is determined by the period of neuron firing ...

, also known as timing theory. These theories are closely linked with the volley principle or

volley theory Volley theory states that groups of neurons of the auditory system respond to a sound by firing action potentials slightly out of phase with one another so that when combined, a greater frequency of sound can be encoded and sent to the brain to be a ...

, a mechanism by which groups of neurons can encode the timing of a sound waveform. In all cases,

neural firing An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, ca ...

patterns in time determine the perception of pitch. The combination known as the place–volley theory uses both mechanisms in combination, primarily coding low pitches by

temporal pattern Spatiotemporal patterns are patterns that occur in a wide range of natural phenoma and are characterized by a spatial and a temporal patterning. The general rules of pattern formation hold. In contrast to "static", pure spatial patterns, the ...

and high pitches by rate–place patterns. It is now generally believed that there is good evidence for both mechanisms. The place theory is usually attributed to

Hermann Helmholtz Hermann Ludwig Ferdinand von Helmholtz (31 August 1821 – 8 September 1894) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The Helmholtz Association, ...

, though it was widely believed much earlier. Experiments to distinguish between place theory and rate theory are difficult to devise, because of the strong correlation: large vibrations with low rate are produced at the apical end of the basilar membrane while large vibrations with high rate are produced at the basal end. The two can be controlled independently using

cochlear implant A cochlear implant (CI) is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech unde ...

s: pulses with a range of rates can be applied via electrodes distributed along the membrane. Experiments using implant recipients showed that, at low stimulation rates, ratings of pitch on a pitch scale were proportional to the log of stimulation rate, but also decreased with distance from the round window. At higher rates, the effect of rate was weaker, but the effect of place was strong.

References

Hearing {{biology-stub