Professional Term Introduction
1. Acoustic Emission: The acoustic emission refer to the instantaneous elastic wave generated by the rapid release of energy from local stress concentration sources in materials.
2. Otoacoustic Emission: The otoacoustic emission refer to the audio sound produced in the cochlea, transmitted by ossicular chain and tympanic membrane and released to the external auditory canal in the absence of sound stimulation.
The principle is generally believed to be that the outer hair cells in the cochlea, move actively through the mechanical connection between the corti apparatus and its adjacent structure by spontaneous or external stimulation, and causing mechanical vibration of the basement membrane. This vibration occurs in the inner ear lymphatic, through the oval window, promote the ossicular chain and tympanic membrane vibration in the form of pressure change conduction, cause the external auditory canal air vibration and release audio energy process finally. Because the frequency of the released audio sound is usually in hundreds to thousands of Hertz, which happen to be within the normal hearing frequency range of the human ear (20 ~ 20,000 Hz), it is called otoacoustic emission.
The otoacoustic emission audiometer, jointly developed by Tsinghua University and Beijing Acoustic Science, is a medical device used for automatic testing of human ear hearing. It is composed of earphone and low noise microphone system.