/**
 * Down-mix interleaved channel data to a single mono channel by averaging.
 *
 * Channels of differing lengths are truncated to the shortest one, which is
 * what browsers hand back for malformed files.
 */
export declare function toMono(channels: readonly Float32Array[]): Float32Array;
/**
 * Resample a mono signal with linear interpolation.
 *
 * Linear interpolation is intentionally simple: reference audio is band
 * limited by the model front-end anyway, and this keeps the library free of
 * a polyphase filter implementation for v0.1.
 */
export declare function resample(samples: Float32Array, fromRate: number, toRate: number): Float32Array;
/**
 * Scale a signal so that its loudest sample sits exactly at `targetPeak`.
 * Silent input is returned unchanged instead of being amplified into noise.
 */
export declare function normalizePeak(samples: Float32Array, targetPeak?: number): Float32Array;
/**
 * Drop leading and trailing samples whose magnitude stays below `threshold`.
 * Quiet passages inside the signal are preserved.
 */
export declare function trimSilence(samples: Float32Array, threshold?: number): Float32Array;
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