/// <reference types="node" />
import { Transform, TransformCallback } from "stream";
import { SpectralMagnitudesChunk } from "./SpectralMagnitudes";
import { Smp, Hz } from "../global";
interface SpectralFlatnessChunk {
    /** The spectral flatness of the signal frame. */
    flatness: number;
    flatnessByChannel?: number[];
    /** The (onset) time of the signal frame in samples. */
    time: Smp;
    /** Sampling frequency at which fft was performed. */
    sampleRate: Hz;
}
/** Calculate the flatness of a SpectralMagnitudes stream. Please pipe directly
 * from a (Mono)SpectralMagnitudes object.
 * Can be used as a measure of noisiness.
*/
declare class MonoSpectralFlatness extends Transform {
    constructor();
    _transform(chunk: SpectralMagnitudesChunk, encoding: string, callback: TransformCallback): void;
}
export { MonoSpectralFlatness, SpectralFlatnessChunk };