Young Brunette Girl With A Modern Hi-fi System

Semblance of realism
Stereophonic sound provided a partial solution to the problem of creating some semblance of the illusion of live orchestral performers by creating a phantom middle channel when the listener sits exactly in the middle of the two front loudspeakers. When the listener moves slightly to the side, however, this phantom channel disappears or is greatly reduced. An attempt to provide for the reproduction of the reverberation was tried in the 1970s through quadraphonic sound but, again, the technology at that time was insufficient for the task. Consumers did not want to pay the additional costs and space required for the marginal improvements in realism. With the rise in popularity of home theatre, however, multi-channel playback systems became affordable, and many consumers were willing to tolerate the six to eight channels required in a home theater. The advances made in signal processors to synthesize an approximation of a good concert hall can now provide a somewhat more realistic illusion of listening in a concert hall.
In addition to spatial realism, the playback of music must be subjectively free from noise to achieve realism. The compact disc (CD) provides about 90 decibels of dynamic range, which is about as much as most people can tolerate in an average living room.
Audio equipment must be able to reproduce frequencies high enough and low enough to be realistic. The human hearing range, for healthy young persons, is 20 Hz to 20,000 Hz. Most adults can't hear higher than 15 kHz. CDs are capable of reproducing frequencies as low as 10 Hz and as high as 22.05 kHz, making them adequate, in range, to reproduce all the frequencies that people can hear.