Human sound-quality judgments are skewed by expectation biases, not just the sound itself.

Evidence

The major issue is that in the most common listening situations humans are not reliable judges of sound quality. We easily form opinions, but they are influenced by factors that have nothing to do with the sound itself—a form of the “placebo effect”. How a product looks, its price, size, reviewers’ comments, internet chat and more all lead to expectations that we simply cannot ignore. Musicians, professional audio engineers and product reviewers, despite their experience, are also susceptible to these biases. Peer pressure, marketing influences and often the ego are involved as their product choices reflect their professional judgment. — Toole, Floyd E, Sound reproduction- the acoustics and…, 39

Categorization

• XREF: Connects to decades of blind-testing methodology in audio and to the placebo effect literature in medicine; also echo of how expert judgment is unreliable in other perception domains.
• DEFINE: Defines expectation bias in listening evaluation as a form of placebo effect.