The term "high fidelity" attained broad usage in the 1930s, and the post-war years are often labeled as a golden age of hi-fi. In a synoptic history of reproductive technologies, it should be noted that the documentary genre emerged in the 1930s, and in those same golden years picture-magazines (and socially concerned photography) graced the coffee tables of most middle-class homes. The common thread between both enterprises is a quest for particular notions of fidelity.
An examination of the etymology and history of fidelity as a description is useful. According to the O.E.D., the word was borrowed from the French fidelis in the early 16th century to describe faithfulness and fealty to a person, party, or bond. The connection to oath or bond falls away quickly, but it retains a connection with testimony. Nonetheless, its usage as a faithfulness to truth and reality disappears in the late nineteenth century. Concurrently, it becomes attached to reproductive technologies, at first the telephone and then radio. Fidelity to voice is recognized in Marconi's 1878 patent on radio.
The evolution is an interesting one; instead of a fidelity to a static truth or reality, fidelity is used most frequently to identify a sort of exactitude of message, a faithfulness to an original. Truth abruptly drops out of the equation. In a historical context, it seems to me that documentary was introduced as a remedy for truth. By that I mean that "true stories" (including true romances and true crime) was the growth segment of the publishing market in the 1920s and 30s and documentary film and photography countered with faith (as in faithfulness and exactitude) rather than truth claims, a counterrevolution of a sort.
I think that this suggests an interesting thing about documentary and musical recording techniques. They are not necessarily married to concepts of fact and truth, as is so often assumed. The facile reference to the presence of fiction in documentary, or artificiality in sound reproduction, doesn't really stick as damning evidence against them. Documentary (and high fidelity) claims are more directly connected to asking a viewer/listener to make a leap of faith in accepting that the worlds they portray as significant. The criterion of faithfulness refers to a faith in a message worth hearing/seeing, not to "truth."1
Hence, there is a deep connection to what Wordsworth and Coleridge termed "the momentary suspension of disbelief that constitutes poetic faith" in both recorded music and documentary film/photography. Perfection and authenticity are a matter of subjective rather than objective perception. In fact, it seems to me that "objective perception" is oxymoronic when applied to human receivers.
It makes sense to keep the gulf between fidelity and truth wide and deep. Claims of quasi-scientific truth work for accuracy of waveforms, or correspondance of brightness zones, but these things do not tell us much about human perception (and the attendent attachment of meaning). They contribute, of course, but ultimately fidelity is a matter of faith not truth. Perfection is in the eye/ear of the beholder.
An interesting sidebar emerges with the survival of an arcane sense of fidelity: fidelity insurance is insurance against dishonesty (such as employee theft). Rather than making the claim that all documentary photographs are false or untrue, one might suggest that some messages are dishonest and exploitive. That makes much more sense to me.
1The rhetorical campaigns of Lewis Hine against child labor springs to mind here— the effectiveness of Hine's photo-textual broadsides rests not on the truthfulness of his depiction of conditions, but rather in the faith that those conditions were abhorrent and in need of change.