Producing pitches

• In the western classical tradition, instruments fall into one of four main groups: strings, woodwind, brass and percussion. The way in which an instrument produces pitches (strings, reed, mouthpiece, etc.) influences the sound's harmonic content and, therefore, frequency content. Harmonics are additional, higher tones produced by an instrument that are related to the basic pitch the instrument produces.
  
  

Timbre - "Tone Color"

• Musical instruments also have a characteristic "tone color", known as "timbre" (pronounced "tam-ber"). The timber is affected by the size, shape and materials used to build the instrument. For example, a metal drum will sound different than a wooden drum of the same size and pitch.
  
  

Analyzing sound

• To analyze sound, it must first be converted into an electrical signal via a microphone. This signal can then be fed into a computer and, through a process called Fourier analysis, complex musical sounds are analyzed and the basic waveforms of which they are composed are revealed. When these results are displayed on a graph representing the sound spectrum from 20 Hz to 20,000 Hz, it is referred to as a spectrum analysis.
  
  

Sound synthesis

• By breaking down a complex sound into its basic constituent waveforms, engineers learn the "recipe", so to speak, for synthesizing sounds. Synthesizers consist of a series of oscillators that produce a variety of basic waveforms and mixers to combine and influence these tones. In this way, synthesizers are programmed to simulate the sound of strings, woodwinds, brass and percussive instruments by manipulating sound generators.
  
  

Music production

• Spectrum analysis is also helpful in the process of recording, mixing and mastering music. Although audio engineers are often able to recognize frequencies by ear, a visual representation of sound is often very useful when equalizing individual instruments or adjusting final mixes and masters. Additionally, spectrum analysis is used to measure the frequency response of rooms in recording studios in order to plan proper acoustic treatments.