“ROLE OF ULTRASOUND IN VOCAL CORD PALSY”

Abstract

Phonation is beyond doubt one of the highest functions of the human larynx. The vocal cords, also known as vocal cords, as the name suggests are infolding of mucosa aligned horizontally. The phonatory process, or voicing, occurs when air is expelled from the lungs through the glottis, creating a pressure drop across the larynx. When this drop becomes sufciently large, the vocal cords start to oscillate. The motion of the vocal cords during oscillation is mostly lateral, though there is also some superior component as well. However, there is almost no motion along the length of the vocal cords. The oscillation of the vocal cords serves to modulate the pressure and ow of the air through the larynx, and this modulated airow is the main component of the sound. The sound that the larynx produces is a harmonic series. In other words, it consists of a fundamental tone (called the fundamental frequency, the main acoustic cue for the percept pitch) accompanied by harmonic overtones, which are multiples of the (1) fundamental frequency .