The topic of this week was the auditory system. That is the mechanism of the brain that detects and processes sound waves. The protagonist of the auditory system is the cochlea: a spiral shaped structure made of bone. In the cochlea sound waves cause vibration of basal membrane. Sound frequency affects the vibration so that higher frequencies vibrate the base of the basal membrane more but dissipate fast while lower frequencies reach further inside the cochlea. Hair cells in the vibrating area are depolarized and the frequency of the sound can be determined by which hair cells send out signals. This mechanism to determine pitch is another unique way that evolution has developed to observe our environment and communicate with each other.
Detecting sounds is only the first part of the auditory system. Processing the information is another important part of the system. The important information in sound includes intensity, frequency and localization. Intensity obviously tells us how loud sounds are and louder sounds are probably more important than quiet ones. Frequency allows us to differentiate sounds and understand speech for an example. Localization is needed to determine where the sounds are coming from.
Information in the auditory system goes in two directions. Not only does the brain receive information from the ear, it also sends out instructions to the ear so that we can focus on the important frequencies and adjust to different intensities. The mechanisms of auditory system are interesting and audio information is essential in observing our environment and communicating with each other.