For me, singing has profound effects because it is actual physical motion and not just something you're visualizing in your head or symbolically attaching to an object. It has psychological and physical effects, so it is not a stretch that it would also have spiritual effects.
When you enter Heathenry, the practice of sung spells is called Galdr while the practice of calling spirits is Vadlokkur (history attests to this through the poetry of the Sagas).
when you enter New Age spiritual and scientific thought, everything is made up of vibrations and singing actually alters those vibrations.
Song is a part of almost, if not every, culture in the world. There are very many examples where song can enhance what one is doing that it only takes a search away to figure out how it all works together.