Frequency theory is a theory of hearing that was first proposed by Rutherford in 1886. It states that the pitch of a sound is determined by the frequency of the sound waves that stimulate the hair cells in the cochlea. The cochlea is a spiral-shaped structure in the inner ear that is filled with fluid and lined with hair cells. When sound waves enter the ear, they cause the fluid in the cochlea to vibrate. These vibrations are then transmitted to the hair cells, which convert them into electrical signals that are sent to the brain.
This theory of how we hear sounds states that there are pulses that travel up the auditory nerve, carrying the information about sound to the brain for processing, and that the rate of this pulse matched the frequency of whatever tone you are hearing exactly. We thus hear the tone because the pulse traveling up the auditory nerve matches the actual tone. Essentially, we are getting a copy of the real sound.
Characteristics
Frequency theory is based on the following assumptions:
- The hair cells in the cochlea are arranged in a spiral pattern.
- The hair cells are sensitive to different frequencies of sound waves.
- The higher the frequency of the sound wave, the closer the hair cell is to the base of the cochlea.
- When a hair cell is stimulated by a sound wave, it sends an electrical signal to the brain.
- The brain interprets these signals as different pitches.
Related Terms
- Place theory: A theory of hearing that states that the pitch of a sound is determined by the place on the basilar membrane where the hair cells are stimulated.
- Volley theory: A theory of hearing that states that both frequency theory and place theory are correct, and that pitch is determined by a combination of the two mechanisms.
- Cochlea: A spiral-shaped structure in the inner ear that is filled with fluid and lined with hair cells.
- Hair cells: Sensory cells in the cochlea that are responsible for hearing.
- Auditory nerve: A nerve that carries signals from the hair cells in the cochlea to the brain.
- Brain: The organ that interprets signals from the auditory nerve and creates the perception of sound.
History
Frequency theory was first proposed by Rutherford in 1886. He suggested that the pitch of a sound is determined by the frequency of the sound waves that stimulate the hair cells in the cochlea. This theory was based on the observation that the hair cells in the cochlea are arranged in a spiral pattern, with the high-frequency hair cells located near the base of the cochlea and the low-frequency hair cells located near the apex of the cochlea.
Evidence for Frequency Theory
There is a number of evidence that supports frequency theory. For example, it has been shown that the hair cells in the cochlea are indeed sensitive to different frequencies of sound waves. Additionally, it has been shown that damage to the hair cells in the cochlea can lead to hearing loss, particularly at high frequencies.
Limitations of Frequency Theory
Frequency theory is not without its limitations. For example, it cannot explain how we are able to hear sounds that have a wide range of frequencies, such as music. Additionally, it cannot explain how we are able to hear sounds that are very quiet.
Conclusion
Frequency theory is one of the two main theories of hearing. It states that the pitch of a sound is determined by the frequency of the sound waves that stimulate the hair cells in the cochlea. This theory is supported by a number of evidence, but it does have some limitations.