/** True when this browser can analyse audio at all. */
export declare function isAudioSupported(): boolean;
/**
 * The page's shared AudioContext, created on first use. Call it from a
 * user gesture (the microphone button) where you can: Safari only lets a
 * context start inside one. It is resumed on every call, so a context the
 * browser suspended in the background picks up again.
 */
export declare function getAudioContext(): AudioContext | null;
export interface AnalyserLease {
    analyser: AnalyserNode;
    release: () => void;
}
/**
 * An AnalyserNode fed by `stream`, plus the function that tears it down.
 * Returns null when the browser has no Web Audio or the stream carries no
 * audio track.
 */
export declare function acquireAnalyser(stream: MediaStream): AnalyserLease | null;