Exactly one voice is the default, and it is the first
On a Blink browser, exactly one voice has default set, and it is the first. N/A on other engines and when no voices arrive (severity: warn).
What a detector infers
Chromium assembles one voice list — the operating system's voices first, then extension voices such as Google's network voices — and marks the default with a single line in speech_synthesis_impl.cc: a voice is the default exactly when it is first. That is the only place the flag is written. So on a Blink browser exactly one voice has default set, and it sits at index 0, whatever the operating system considers its own default voice.
A voice table replayed from elsewhere tends to carry the default somewhere else, twice, or not at all, because whoever built it copied the flags rather than the rule. In the audit's corpus, 265 of 272 Blink captures follow the rule; the seven that do not have defaults at positions 0 and 3 on Windows, or none at all on a 176-voice macOS list.
Chrome and Edge (321 voices) on Windows and Chrome on Linux all measured a single default at index 0, and a voice-table spoof written for the test put it at index 3. Firefox and Safari mark the OS default voice wherever it sits, so the row is N/A outside Blink, and an empty list is N/A. The other speech rows read what the voices are; this one reads how the list was built.
How to resolve it
Let the browser build the voice list from the host's speech engine. A list with its default anywhere but first, or with more than one default, was not assembled by Chromium.
Nearby checks in Environment & locale
- Google's network voices arrive as Google's exact set
google-voices-exact-setBranded Google Chrome on Windows, macOS and Linux adds a set of network voices from a component extension whose manifest lists exactly 19 of… - The local voices come from the claimed OS's speech engine
local-voice-vendor-vs-osVoices marked localService are the host's own speech engine, enumerated by the browser from the operating system, and their names say where… - Intl's default locale is a UI locale desktop Chrome ships
intl-is-a-chrome-ui-localeChrome's Intl default locale — what new Intl.DateTimeFormat().resolvedOptions().locale returns — is not the operating system's region. - The browser's own UI strings are in the language Intl resolves
validation-message-vs-intlThe messages a browser writes itself — 'Please fill in this field.' under an empty required input — come from the renderer's resource… - MediaCapabilities powerEfficient agrees with WebCodecs prefer-hardware
power-efficient-vs-webcodecsMediaCapabilities.decodingInfo() reports whether decoding a format would be power-efficient, and WebCodecs' VideoDecoder.isConfigSupported()… - A playback AudioContext buffers more than an interactive one
playback-hint-buffers-moreAn AudioContext created with latencyHint 'playback' asks for a larger buffer than one created with 'interactive', and Chrome honours the… - AudioContext latencies are values Chrome's audio stack can produce
audio-latency-render-stateTwo AudioContext latencies are produced by the audio stack at particular moments, and their values are constrained in ways a constant is… - A granted geolocation fix carries a real accuracy
geolocation-has-accuracyEvery position a real location provider returns comes with an accuracy: the radius, in metres, within which the true position probably lies.
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Environment & locale checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Environment & locale — the family voice-default-is-first belongs to.