private function getNextBeat(Voice $beat, $bIndex)
{
$next = null;
for ($b = $bIndex + 1; $b < $beat->getBeat()->getMeasure()->countBeats(); $b++) {
$current = $beat->getBeat()->getMeasure()->getBeat($b);
if ($current->getStart() > $beat->getBeat()->getStart() && !$current->getVoice($beat->getIndex())->isEmpty()) {
if ($next === null || $current->getStart() < $next->getBeat()->getStart()) {
$next = $current->getVoice($beat->getIndex());
}
}
}
return $next;
}
