Checking for idle hover using tooltips

So I recently started using tooltips to detect when the mouse hovers over a GUI.Button to play a sound. I have it so it works when you hover over the button it fires the sound, but if the mouse stays hovering the button it keeps refiring the sound. I know it has something to do with the tooltips setup I just cant figure out what. Please help.

 private bool canHoverSound = true;
 void OnGUI()
     {
             diffW = (Screen.width / (setWidth / 100)) / 100;
             diffH = (Screen.height / (setHeight / 100)) / 100;
             if (GUI.Button(new Rect(posX * diffW, posY * diffH, sizeX * diffW, sizeY * diffH), new GUIContent("","Mouse Over Button"), defaultStyle))
             {
                 //BUT CLICK STUFF                
             }
 
             if (GUI.tooltip == "Mouse Over Button")
             {
                 if (canHoverSound)
                 {
                     FMOD.Studio.PLAYBACK_STATE state;
                     FMOD_StudioSystem.ERRCHECK(hoverSound.getPlaybackState(out state));
                     if (state == FMOD.Studio.PLAYBACK_STATE.STOPPED)
                     {
                         hoverSound.start();
                     }
                     canHoverSound = false;
                 }
 
             }
             else
             {
                 canHoverSound = true;
             }
 
     }