/** Which of the two singleton live regions a message is routed to. */
export type AnnouncePoliteness = 'polite' | 'assertive';
/** How long successive announcements keep merging into one write before the region updates. */
export declare const ANNOUNCE_DEBOUNCE_MS = 150;
/** Owns the `aria-live` regions and their debounced writes; one instance per process (or per Angular injector). */
export declare class Announcer {
    private readonly regions;
    /**
     * Schedules `message` for the region; a burst inside one debounce window collapses to its last message, and a repeat of the text already shown is re-announced.
     */
    announce(message: string, politeness?: AnnouncePoliteness): void;
    /** Empties the region(s) and drops anything still pending; pass a politeness to clear just one. */
    clear(politeness?: AnnouncePoliteness): void;
    /** Clears and removes the regions from the document. */
    destroy(): void;
    private regionFor;
}
export declare function hostLiveAnnouncerRegions(): void;