/**
 * Calculate FFT - Based on https://github.com/corbanbrook/dsp.js
 *
 * @param {Number} bufferSize Buffer size
 * @param {Number} sampleRate Sample rate
 * @param {Function} windowFunc Window function
 * @param {Number} alpha Alpha channel
 */
export default function FFT(bufferSize: any, sampleRate: any, windowFunc: any, alpha: any): void;