Volume (Intensity)
When a sound is created, air molecules are set in motion, resulting in vibrations; the higher the frequency of
vibrations, the higher the pitch. The volumeof the sound, however, is determined by how much the air mole-
cules expand and compress (the amplitude), which affects the air pressure. The greater the increase and decrease
in air pressure, the greater the sound’s intensity. Asound wave’s intensity is related to its amplitude. Musicians
use the term dynamics when talking about intensity.
Note:
- Intensity is measured in decibels(dB) beginning with 0 dB, which is the softest sound that humans can
hear. - Examples of sounds measured in dB include a whisper (20 dB) to the sound of a large orchestra (98 dB).
Sounds at 160 dB will cause instant and irreparable hearing loss.
Color (Timbre)
Each sound created by an instrument consists of more than one frequency. These frequencies are not heard as
discrete ones, but as a combination of the frequencies. The instruments from around the world are classified by
type:
- Aerophones (flutes, brasses, reeds) where air vibrates through a column;
- Chordophones (stringed instruments) where a string vibrates;
- Idiophones (percussive instruments such as bells and shakers) where the instrument produces the sound
(idiomeans “itself”); - Membranophones (drums) where a membrane vibrates.
Similar instruments within each classification have a similar series of frequencies. This aspect of sound is called
timbre,or color;for example, a trumpet has a distinctly different sound from a violin, and a singer sounds
noticeably different from a sitar.
APPENDIX 2
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