Audio Manager

// Recommended way, more verbose.
private AudioClip jumpSound;

// It's recommended to cache the AudioEmitter and use its reference.
private AudioEmitter playerSource;

private void Start()
{
    // To avoid additional overhead, do not assign an 
    // AudioEmitter in a function called every frame.
    playerSource = AudioManager.Instance.RegisterSource("PlayerSource", transform);
}

private void Update()
{
    if (InputManager.GetButtonDown("Jump"))
    {
        // With the cached reference it's easy 
        // and fast to access AudioEmitter and play a sound.
        playerSource.Play(jumpSound, 0.5f);
    }
}

// Alternative mode, less verbose yet expensive.
private AudioClip jumpSound;

private void Start()
{
    // Registers the AudioEmitter "PlayerSource"
    // allowing you to use it by using its name.
    AudioManager.Instance.RegisterSource("PlayerSource", transform);
}

private void Update()
{
    if (InputManager.GetButtonDown("Jump"))
    {
        // Search if there is any AudioEmitter with that name, 
        // then play the sound.
        AudioManager.Instance.Play("PlayerSource", jumpSound, 0.5f);
    }
}