-- | Stacks the channels of two audio files together. Can also adjust volumes.
merge' :: (Double, Audio r c1) -> (Double, Audio r c2) -> Audio r (c1 + c2)
merge' (a, Audio x) (b, Audio y) = Audio $ Merge [(a, x), (b, y)]
merge' :: (Double, Audio r c1) -> (Double, Audio r c2) -> Audio r (c1 + c2)
merge' (a, Audio x) (b, Audio y) = Audio $ Merge [(a, x), (b, y)]
merge' (a, Audio x) (b, Audio y) = Audio $ Merge [(a, x), (b, y)]