Piano tuning stretched so far it has become a required sound

Evidence

In fact, the piano is tuned in part by listening for beats with upper partials, starting at the lowest notes. The partials are a bit sharp, which means that successively higher notes are set at frequencies that are “stretched” relative to perfect octaves. Once again, we have become used to this; perhaps we now require it. — Eric J. Heller, Why You Hear What You Hear- An…, 1825

Categorization

• XREF: Channels One Square Inch of Silence’s point about normalization — we require what we have become habituated to, whether noises or stretched tuning.
• SEED: The ‘become used to it / now require it’ line could anchor a short essay on how tuning conventions encode remembered physical imperfection into normative aesthetics.