Speaking of hiss, in the recording studios, many musicians and engineers dislike Dolby noise reduction because they feel it makes the music sound dull for, among other reasons, removal of the hiss. Since the tape hiss is a constant, as opposed to a random pop or click on an LP, the ear tends to ignore it, as we do the constant din of human existence. The hiss becomes perceived as brighter = better high frequency response, mostly when A/B'd against a tape using noise reduction.
