A text-to-speech demo can sound polished and still fail the person who needs it: a product name is mangled, a dosage or account value is spoken ambiguously, the voice switches accent halfway through a page, or the player cannot be controlled without a mouse. If the job is to make product help usable by listening, “sounds human” is not an acceptance criterion.

The practical recommendation is to treat a synthetic voice as one delivery format in an accessible content system, not as a substitute for accessible source content or for users’ existing screen readers. Freeze a model and voice version, test the same short set of real content with blind listeners who include the intended users, and block release on any meaning-changing error. The asset below is a 15-case acceptance protocol: twelve content fixtures plus three player-control checks. It is a test design, not a claim that any provider passed it.

The product page that motivated this angle is the site's voice AI overview .…