/**
 * Spectral centroid per frame.
 * centroid[t] = sum_f freq[f] * S_norm[f][t], with per-frame L1 normalization.
 * @param {Float32Array|Array|null} y - time series (or null when S given)
 * @param {Object} options - { sr, S, n_fft, hop_length, win_length, window, center, pad_mode, freq }
 * @returns {Float64Array} centroid frequency (Hz) per frame
 */
export function spectral_centroid(y?: Float32Array | any[] | null, options?: any): Float64Array;
/**
 * p'th-order spectral bandwidth.
 * bw[t] = (sum_f S_norm[f][t] * |freq[f] - centroid[t]|**p) ** (1/p)
 * @returns {Float64Array} bandwidth per frame
 */
export function spectral_bandwidth(y?: any, options?: {}): Float64Array;
/**
 * Roll-off frequency: the minimum
 * frequency bin whose cumulative energy reaches roll_percent of the total.
 * @returns {Float64Array} rolloff frequency (Hz) per frame
 */
export function spectral_rolloff(y?: any, options?: {}): Float64Array;
/**
 * Spectral flatness:
 * geometric mean / arithmetic mean of max(amin, S**power) per frame.
 * (Formula salvaged from xa-spectral.js — verified against fixtures —
 * re-hosted here with correct freq-major orientation.)
 * @returns {Float64Array} flatness in [0, 1] per frame
 */
export function spectral_flatness(y?: any, options?: {}): Float64Array;
/**
 * Spectral contrast.
 * Octave-band peak/valley contrast: mean of the top / bottom `quantile`
 * fraction of sorted magnitudes per band, then power_to_db difference.
 * @returns {Array<Float64Array>} [n_bands + 1][n_frames]
 */
export function spectral_contrast(y?: any, options?: {}): Array<Float64Array>;
/**
 * Root-mean-square energy per frame.
 * y path: centered constant-padded framing (verified salvage of the
 * xa-spectral rms y-path — numerically exact on fixtures).
 * S path: Parseval-based power from a magnitude spectrogram.
 * @returns {Float64Array} RMS per frame
 */
export function rms(y?: any, options?: {}): Float64Array;
/**
 * Frame-wise zero-crossing rate:
 * edge-padded centering, |v| <= threshold clipped to zero before the sign
 * test, first sample of each frame never counted (pad=False).
 * @returns {Float64Array} fraction of zero crossings per frame
 */
export function zero_crossing_rate(y: any, options?: {}): Float64Array;
export class ParameterError extends Error {
    constructor(message: any);
}