For example, a string clamped at both ends has modes at the fundamental and integer multiples of the fundamental. A tube closed at one end and open at the other, however, can produce only odd modes of vibration, since an antinode is at the open end. In an instrument, the vibrational component set into motion directly by the performer's energy by striking, plucking, bowing, breathing, etc. Coupling A connection between one vibrating component and another. Typical couplings include the air or a bridge.
Couplings can have different resistances in the flow of energy from one component to another.
Impedance is the name of this resistance. An example is the body of the acoustic guitar, or the soundboard and enclosure of the typical modern piano. The auditory system 'synthesizes' the missing component, and we hear the fundamental pitch, even though no energy is there. Eliminate these, and code, with varying bitrate, the spectral output on the disc. Reverse the process, expanding low bitrate to 16-bit stereo audio for playback.