Chambers 20th Century Dictionary(0.00 / 0 votes)Rate this definition: Sibilance. sibâ²i-lans, n. a hissing soundâalso Sibâ²ilancy.âadj. Sibâ²ilant, making a hissing sound.ân. a sibilant letter, as s and z.âv.t. Sibâ²ilÄte, to pronounce with a hissing sound.ân. SibilÄâ²tion, a hissing sound.âadjs.
Definition: A delta wave is a type of high amplitude brain wave found in humans. Delta waves have a frequency from one to four hertz and are measured using an electroencephalogram (EEG). These brain waves are thought to emerge from the thalamus and are generally associated with slow-wave sleep (during stages three and four of the stages of sleep.
There are five main frequency brain waves: Beta, Alpha, Theta, Delta, and Gamma. These brain waves are in constant motion, the brain produces consistent waves at all frequencies. Everything you do or say is regulated by the frequency of brain waves. When we talk to others, for example, our mind is in Beta. The Beta wave has a frequency of 14-28 cycles per second. Beta is the state in which you are active and alert.