A Study Of Speech Physiology Monitor System In The View Of External Photoelectric Glottography

This paper introduces a speech monitor system based on External Photoelectric Glottography(ePGG).The system is used for measuring the open degree of human glottis when they are talking.A traditional Photoelectric Glottography(PGG) usually consists of a fiberscope as light source and a photodiode which placed on the front neck near human cricoids cartilage of the larynx. It measures the open degree of the glottis by measuring the light intensity. However, this method requires putting an invasive fiberscope into the subjects’ body, which requires a professional physician and increased complexity. The solution proposed in this paper has similar principle with PGG but uses external infrared LED as the light source which avoids the invasion.The system consists of two parts, a sensor subsystem and a signal acquisition subsystem. The sensor subsystem is the core of the system for measuring the degree of opening of the glottis, including a transmitter and a receiver. The transmitter is used for providing a light source, which has a characteristic frequency and a constant intensity. The characteristic frequency is achieved by modulation and the constant intensity is achieved by constant electric current source. The receiving end is used for measuring the intensity of light passing through the glottis. First it converts the optical signal into an electrical signal, amplifies the signal to the intensity that could drive the next level circuit, then filters the signal by a band-pass filter, and detects output from the modulated signal to recover the original signal, finally output the signal represents the open degree of the glottis after filtering by a low-pass filter.The signal acquisition system is used for collecting, storing and displaying the ePGG signal, including an embedded system and a PC. The embedded system is based on an ARM core microcontroller, which collects the speech signal and the ePGG signal synchronously, converts the two analog signals to digital signal, and then sends them to the PC. The PC displays and stores the receving speech signal and the ePGG signal that facilitates the observating, debugging and further processing.The experimental results showed that the ePGG can effectively measure the open degree of the glottis with much reduced complexity to the traditional PGG system.