Sound is the most prenatally usable stimulus (e.g., fetus is exposed to mother’s voice, breathing, and movements, in addition to many environmental sounds). Sounds begin to be processed between the 16th and 20th weeks of gestation. The fetal auditory system has reached adult abilities of development by birth. (Harris, Maureen. Music and the Young Mind. p 1-2. NY: MENC with Rowman & Littlefield Education, 2009.)

Researchers have long distinguished between noise and sound. Generally, noise is seen as a psychological concept defined as sound that is subjectively perceived as undesirable because it is unpleasant or interferes with important activities. (Baker, Mary Anne, ed. Sex Differences in Human Performance. p 90. NY: John Wiley & Sons, 1987.)

Every cell in the body registers and is influenced by the energy reflected in sound waves. Since sound is energy and energy contains information, the natural acoustical ability of cells allows them to remember the tones of your life. (Pearsall, Paul, PhD. The Heart’s Code. p 110. NY: Broadway Books, 1998.)

Sound has two basic characteristics: loudness, which depends on the size of the sound waves, and pitch, which depends on their frequency. Most acoustic information, such as speech or music, is carried by changes in the amplitude (loudness) and frequency (pitch) of sound waves. (Greenfield, Susan, con. Ed.Brain Power. p 60. MA: The Ivy Press Limited, 1999.)

By listening to the pitch, inflection, lilt, and cadence of a person’s words (e.g., the music of speech), human beings distinguish sounds that are essential to sophisticated communication. Females have a biological edge in this area. (Fisher, Helen, PhD. The First Sex. p 60. NY: Random House, 1999.)