1. This pair of terms refers to a systems ability to reproduce a full (hi-fi) or less than full (lo-fi) audio frequency spectrum (20 to 20,000 Hz) and a favourable (hi-fi) or poor (lo-fi) signal-to-noise ratio, normally applied to an amplifier or a recording.
A key determinant of fidelity is frequency response. This is the measure of the output of a sound-producing body stimulated with frequencies over a given range usually the entire range of hearing (20 to 20,000 Hz). Also called a resonance curve.
The resonances of a musical instrument result in an uneven frequency response of that instrument, whereas for the ideal loudspeaker, the frequency response should be flat, that is, all frequencies should be reproduced equally well to achieve good fidelity. (Reduced from Barry Truax - Handbook for Acoustic Ecology CD-ROM Edition. Cambridge Street Publishing, 1999 - CSR-CDR 9901)
2. R. Murray Schaffer introduced the concept of a hi-fi and lo-fi soundscape. In a hi-fi soundscape, we can clearly perceive sounds and their orientation (location and distance) within the acoustic space. In a lo-fi soundscape, the sonic space is confused, individual sounds lose their identity, and masking (for example by constant traffic noise) is common.
3. Much Electroacoustic Music could be said to display an aesthetic preference for hi-fi recording, reproduction and listening situation. Some practitioners conceive of an ideal situation in which there is a transparency of the technical means and proceedures used in composition and performance. Others draw the attention of the listener to the technical means of production, to the extent that this may become an aspect of the signifying potential, narrativity or discourse of the music. Indeed, it is possible to create a musically significant continuum between Hi-Fi and Lo-Fi during the course of a piece. Some pracitioners and genres (e.g. Glitch) celebrate and aesthetically privilege a lo-fi approach to sound.
See also:Acoustic Ecology, Noise Pollution, Soundscape Studies