type Vec3 = [number, number, number];
/**
 * AudioOcclusion.ts
 *
 * Advanced obstacle-based audio occlusion and obstruction:
 * - Raycast-based occlusion detection
 * - dB-based transmission loss
 * - Frequency-dependent filtering (realistic "behind wall" muffled sound)
 * - Per-material frequency absorption curves
 *
 * @module audio
 */
/**
 * Frequency-dependent absorption coefficients (0-1 per frequency band)
 */
export interface FrequencyAbsorption {
    125: number;
    250: number;
    500: number;
    1000: number;
    2000: number;
    4000: number;
    8000: number;
}
export interface OcclusionMaterial {
    id: string;
    name: string;
    absorptionCoefficient: number;
    transmissionLoss: number;
    frequencyAbsorption?: FrequencyAbsorption;
}
export interface OcclusionResult {
    sourceId: string;
    occluded: boolean;
    occlusionFactor: number;
    hitCount: number;
    totalTransmissionLoss: number;
    materials: string[];
    lowPassCutoff: number;
    frequencyAttenuation: Partial<FrequencyAbsorption>;
}
export interface OcclusionRay {
    origin: Vec3;
    direction: Vec3;
    maxDistance: number;
}
export interface OcclusionHit {
    distance: number;
    materialId: string;
    thickness: number;
}
export declare const OCCLUSION_MATERIALS: Record<string, OcclusionMaterial>;
export type RaycastProvider = (ray: OcclusionRay) => OcclusionHit[];
export declare class AudioOcclusionSystem {
    private materials;
    private raycastProvider;
    private maxTransmissionLoss;
    private cache;
    private enableFrequencyFiltering;
    constructor();
    setRaycastProvider(provider: RaycastProvider): void;
    registerMaterial(material: OcclusionMaterial): void;
    getMaterial(id: string): OcclusionMaterial | undefined;
    setMaxTransmissionLoss(db: number): void;
    setFrequencyFilteringEnabled(enabled: boolean): void;
    isFrequencyFilteringEnabled(): boolean;
    /**
     * Compute occlusion between listener and a source.
     * Uses the registered raycast provider to detect obstacles.
     * Now includes frequency-dependent filtering for realistic muffled sound.
     */
    computeOcclusion(listenPos: Vec3, sourcePos: Vec3, sourceId: string): OcclusionResult;
    /**
     * Compute without raycasting — direct manual hit specification.
     * Useful for testing or pre-computed occlusion.
     */
    computeFromHits(sourceId: string, hits: OcclusionHit[]): OcclusionResult;
    /**
     * Get the volume multiplier for a given occlusion factor.
     * Converts transmission loss to a linear volume reduction.
     */
    getVolumeMultiplier(occlusionFactor: number): number;
    getCachedResult(sourceId: string): OcclusionResult | undefined;
    clearCache(): void;
    /**
     * Calculate low-pass filter cutoff frequency based on occlusion.
     * Returns cutoff in Hz (500Hz fully occluded, 22kHz no occlusion).
     */
    private calculateLowPassCutoff;
    /**
     * Get frequency attenuation for a specific source.
     * Returns per-band attenuation (0-1, where 1 = fully absorbed).
     */
    getFrequencyAttenuation(sourceId: string): Partial<FrequencyAbsorption>;
    /**
     * Get low-pass cutoff for a specific source.
     */
    getLowPassCutoff(sourceId: string): number;
}
export {};
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