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MUSICAL SCIENCE  Plucking an electric guitar
string causes it to vibrate,
In scientific terms, all music works in creating a sound wave which is
then amplified electronically.
the same way. When someone sings,
an instrument is played, or a stereo
plays a record, it creates a sound
wave—a movement of air particles—
that travels through the air to our ears.
The frequency of the sound wave—
how quickly it vibrates—determines
whether we hear the sound as a high
or a low pitch. High-frequency waves
are detected as high-pitch notes, while
low-frequency waves are detected
as low-pitched notes.

 An orchestra may have as many as 36
stringed instruments: 20 violins (divided in two
between first violins, which play the melodies,
and second violins, which play slightly lower
notes), 10 cellos, and 6 doubles basses.

Written music Chords Conductors Choirs
Music is written on a set Individual notes can be The conductor stands at Choirs use differently
of five horizontal lines combined to form chords the front of the orchestra pitched voices to
known as a stave (see page 18). directing the performance create harmonies 7
(see page 16–17). (see page 19). (see pages 20–21).