Announcement urgency is graded; non-critical updates must not interrupt

What it is

Updates that must be heard do not all have to cut into the sentence currently being spoken. Politeness (aria-live politeness) grades the push: off does not push, polite waits for the current sentence, assertive flushes the queue and speaks now. role="status" sits on the polite side; role="alert" on the assertive side. The question is whether this fact is worth interrupting the instructions being heard or the field currently being echoed. Non-critical copy shoved into assertive costs the user the current sentence and their place in the form.

That is not “live on the wrong container.” The container can be right and the attribute legal while the grade is still wrong.

Why it happens

The reader keeps a speech queue. Polite enqueues; assertive drops or suspends unfinished speech. Working memory does not hold “half a sentence of instructions + a badge + the label of the field being typed.” The cost of an interrupt is not extra words; it is a cut in the auditory context of the current task, and recovery means finding focus again and re-hearing the label.

The second layer is the test for “critical”: assertive is for facts that, unheard right now, cause an error that is hard to undo — payment failure, a session about to expire, a submit error while focus is elsewhere. Result counts, “draft saved,” “someone is typing” can wait a sentence without irreversible loss, so they queue. There is no middle grade for “somewhat important but must not interrupt”; stuffing those into assertive uses the only interrupt channel as a volume knob.

Studying it

Have participants read instructions or fill a multi-step form in a reader while two classes of update arrive: critical (submit failed) and non-critical (saved, people online). Cross with three politeness grades. Dependent measures: wrong field values, requests to re-hear instructions, self-reported interrupts — not satisfaction. NVDA and JAWS delay polite differently; run the same script on both.

Independent variables: politeness, whether the update is irreversible, whether the user is mid-input. Dependent variables: task errors, flushed speech, keystrokes to recover place.

Where it stops holding

Some mobile readers barely speak polite, so authors promote everything to assertive to “hear it,” and grading collapses to one bucket. Users can turn hinting down until even assertive is swallowed; product correctness cannot be bet on “alert always interrupts.” In live collaboration, “someone else selected this cell” is critical for the operator and not for a bystander; grade follows role. While a long description is being spoken, even a true assertive sounds brutal; the repair is to make the long description pausable, not to demote the emergency into polite.

Applying it

• Tabulate every dynamic message as polite or assertive; default polite; assertive only for irreversible risk.
• Success, save, counts, and presence go in status / polite; alert when the error fires and focus is not on that field.
• Do not use assertive as the universal “make sure they hear it” switch.
• How to check: fill a form in headphones while a save notice and a real submit error fire in sequence. If the save notice cuts into the field label, or the error is queued until after the user has left, the grade is wrong.

Related

• Same group: J5.12.1 Updates that happen without navigation must be announced to AT · J5.12.3 Transient loading and error feedback is skipped unless it enters a live region · J5.12.4 Too-frequent announcements become noise
• Nearby: J5.11 Correct use of ARIA · J4.08 Attention and distraction
• Search terms: aria-live politeness · assertive · role=status