Timbre is a sound’s identity. This identity depends on the
physical characteristics of the sound’s medium (the matter or
substance that supports the sound). Let’s take an A at 440 Hertz
produced at 60 decibels: we can immediately tell if the sound
was emitted from a violin, saxophone, or piano. Yet, even though
the instrument is different, it’s the same note and the same
amplitude. The difference is in the sound production: string,
air column, etc.. Plus, the sound isn’t generated by the same
“tool”: a bow for violin strings, a reed and an air column for
the sax, and felt covered hammers that strike the piano strings.
It’s the different physical characteristics of the medium and
the « tool » that determine the characteristic sound waves in
each case. Later we will also see how a sound chamber adds
another dimension to this definition. The most basic waveform is
a sine wave (sinusoid) (Figure 1). It could be considered the
atom of sound. Figure 1: A sine wave (or sinusoid). (click to
enlarge) Pure sinusoidal s