Why no sound? – Simon Says Brain Trainer (color music game) HD Free Review

I paid both the ad removal and the developer donation fee. The sound doesn't work! Does the game require IOS 7 or better? It doesn't say so. I'm on 6.1.3 to avoid the visual degrading that comes with updating an older iPad.
Review by MNRebecca on Simon Says Brain Trainer (color music game) HD Free.