using UnityEngine;

public class BaseClass : MonoBehaviour
{
    GameObject gObject;
    AudioSource audioSource;

    void Start()
    {
        gObject = new GameObject("Audio");
        gObject.transform.position = new Vector3(0,0,-9.5f);

        audioSource = gObject.AddComponent<AudioSource>();
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.A))
        {
            audioSource.clip = ResourceManager.LoadAudioClip("audio.ogg");
            audioSource.Play();
        }
    }

using UnityEngine;
using System.Collections;
using System.IO;

public class ResourceManager {

    static string rootPath = Application.dataPath + "/";

    public static AudioClip LoadAudioClip(string path)
    {
        string file = Directory.GetFiles(rootPath + path, Path.GetFileName(path))[0];

        return Utilities.Instance.PreloadAudioClip(file);
    }
}

using UnityEngine;
using System.Collections;

public sealed class Utilities : MonoBehaviour {

    static Utilities instance;

    public static Utilities Instance
    {
        get {
            if (instance == null)
            {
                GameObject gObject = new GameObject("(Utilities)");
                instance = gObject.AddComponent<Utilities>();
            }
            return instance;
        }
    }

    public AudioClip PreloadAudioClip(string filePath)
    {
        var www = new WWW("file://" + filePath);

        StartCoroutine(Preload(www));

        return  www.GetAudioClip (false, true, AudioType.OGGVORBIS);
    }

    IEnumerator Preload(WWW www)
    {
        while (!www.isDone)
            yield return null;
    }
}

    public static AudioClip LoadAudioClip(string path)
    {
        string file = Directory.GetFiles(rootPath + path, Path.GetFileName(path))[0];
        var www = new WWW("file://" + file);
        while (!www.isDone);
        return www.GetAudioClip(false, true, AudioType.OGGVORBIS);
    }