for (each_frame)
{
    if ((transform.localPosition-previousPosition)<100)
    {
        if (sound.isPlaying && previousPosition == transform.localPosition)
            {
                Debug.Log("Stop");
                sound.Stop();
            }

        else if (!sound.isPlaying && previousPosition != transform.localPosition)
            {
                Debug.Log("Play");
                sound.Play();
            }


            previousPosition = transform.localPosition;
    }
}

iteration 0 (idle)
    sound.isPlaying  = false
    previousPosition = indefinite
    ((previousPosition (indefinite) == transform.localPosition(0))?false & sound.isPlaying == true)=false
    ((previousPosition (indefinite) != transform.localPosition(0))?true & sound.isPlaying == false)=true => sound.isPlaying = true
    previousPosition (indefinite) = transform.localPosition (0);

iteration 1 (move)
    sound.isPlaying  = true
    previousPosition = 0
    ((previousPosition (0) == transform.localPosition(1))?false & sound.isPlaying == true)=false
    ((previousPosition (0) != transform.localPosition(1))?true & sound.isPlaying == false)=true
    previousPosition (indefinite) = transform.localPosition (1);

iteration 2 (stops)
    sound.isPlaying  = true
    previousPosition = 1
    ((previousPosition (1) == transform.localPosition(1))?true & sound.isPlaying == true)=true => sound.isPlaying = false
    previousPosition (1) = transform.localPosition (1);

---------------------------------------------------------------------------------------------------------------------------------------

iteration 0 (idle)
    sound.isPlaying  = false
    previousPosition = indefinite
    ((previousPosition (indefinite) == transform.localPosition(0))?false & sound.isPlaying == true)=false
    ((previousPosition (indefinite) != transform.localPosition(0))?true & sound.isPlaying == false)=true => sound.isPlaying = true
    previousPosition (indefinite) = transform.localPosition (0);

iteration 1 (stops)
    sound.isPlaying  = false
    previousPosition = 1
    ((previousPosition (1) == transform.localPosition(1))?true & sound.isPlaying == true)=true => sound.isPlaying = false
    previousPosition (1) = transform.localPosition (1);