Elements of a Sound
It is recommended that this chapter is read carefully if Analogue sound synthesis is an unfamiliar subject. Experienced users can skip this chapter and move to the chapter - Main features and Operation on Page 14. Elements of a Sound To gain an understanding of how a Synthesizer generates sound it is helpful to have an understanding of the components that make up a sound, be it musical or non musical. The only way that a sound may be detected is by air vibrating the eardrum in a regular, periodic manner. The brain interprets these vibrations (very accurately) into one of an infinite number of different types of sound. Remarkably, any sound may be described by just three terms, and all sounds always have them. They are : * Volume * Pitch * Tone What makes one sound different to another is how these three terms change during the duration of the sound. In a musical synthesizer we deliberately set out to have precise control over these three terms and, in particular, how they can be changed throughout the duration of the sound. These terms are often given different names, Volume is referred to as Amplitude, Pitch as Frequency and Tone as Timbre.
Volume
Pitch Taking the example of air vibrating the ear drum, the pitch is determined by how fast the vibrations are. For an adult human the lowest vibration perceived as sound is about twenty times a second, which the brain interprets as a bass type sound, and the highest is many thousands of times a second, which the brain interprets as a treble type sound.
Wave B is twice the Pitch of Wave A
Wave A
Wave B Time
Tone Musical sounds consist of several different related pitches occurring simultaneously. The loudest is referred to as the �Fundamental� pitch Pitches related to the fundamental are called harmonics. The relative loudness of these harmonics compared to the loudness of all the other harmonics (including the fundamental) determines the tone or �Timbre� of the sound. Volume Volume, which is referred to as the amplitude or loudness of the sound is determined by how large the vibrations are. Very simply, listening to a piano from a metre away would sound louder than if it were fifty metres away.
Wave A is louder than Wave B but is the same pitch
