AudioManager.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AudioManager : MonoBehaviour {
	//singleton
	static AudioManager instance = null;

	//internals
	AudioSource[] audioSources;
	Dictionary<String, AudioClip> audioDictionary; //TODO: clear the cache on scene load?
	GameObject playerObject;

	//BUGFIX: don't stack sounds on the same frame
	List<AudioClip> playedClips = new List<AudioClip> ();

	//volume control
	float loopVolume = 1;
	float oneshotVolume = 1;

	void Awake() {
		//singleton
		if (instance == null) {
			instance = this;
			DontDestroyOnLoad (gameObject);
		} else {
			Destroy (this);
			return;
		}

		//components
		audioSources = GetComponents<AudioSource> ();
		audioSources[0].loop = true;

		//cache loaded sounds
		audioDictionary = new Dictionary<String, AudioClip> ();
	}

	void Update() {
		playedClips.Clear ();
	}

	//the method called
	public static void Play(String filename, Vector3 objPosition, float volume = 1.0f, bool loop = false) {
		instance.PlaySound (filename, objPosition, volume, loop);
	}

	public static void Play(String filename, float volume = 1.0f, bool loop = false) {
		instance.PlaySound (filename, volume, loop);
	}

	void PlaySound(String filename, Vector3 objPosition, float volume, bool loop) {
		//maximum distance
		if (Vector3.Distance (playerObject.transform.position, objPosition) > 1) {
			return;
		}

		PlaySound (filename, volume, loop);
	}

	void PlaySound(String filename, float volume, bool loop) {
		if (!audioDictionary.ContainsKey(filename)) {
			LoadAsset (filename);
		}

		//BUGFIX
		if (playedClips.Contains(audioDictionary[filename])) {
			return;
		}

		if (loop) {
            audioSources[0].clip = audioDictionary [filename]; 
			audioSources[0].volume = volume * loopVolume;
			audioSources[0].Play ();
		} else {
			audioSources[1].PlayOneShot (audioDictionary [filename], volume * oneshotVolume);
		}

		//BUGFIX
		playedClips.Add (audioDictionary [filename]);
	}

	void LoadAsset(String filename) {
		audioDictionary [filename] = Resources.Load<AudioClip> (filename);
	}

	public static void RegisterPlayerObject(GameObject go) {
		instance.playerObject = go;
	}

	//volume control
	public float GetLoopVolume() {
		return loopVolume;
	}

	public void SetLoopVolume(float v) {
		loopVolume = Mathf.Clamp(v, 0f, 1f);
		audioSources[0].volume = loopVolume;
	}

	public float GetOneshotVolume() {
		return oneshotVolume;
	}

	public void SetOneshotVolume(float v) {
		oneshotVolume = Mathf.Clamp(v, 0f, 1f);
	}
}