Now I think about it,I studied languages at school and beyond. For A-level I had to learn various poems by heart, or at least chunks of them. We also had a teacher who was fond of singing, so we learned and sang lots of songs in French and German.

The words of most of the poems are long forgotten, even though I once knew them well enough to be able to analyse them and comment on their style, structure, etc, but I can still remember many songs and carols we learned and sang. This seems to reinforce Jack's original point - that singing in a language, rather than, say, reciting in it, helps you retain language. I still occasionally use phrases from those songs to help me remember certain vocabulary and expressions.

I have occasionally learned a foreign song "phonetically" without any real understanding, but I never retain any of this for long once the original purpose or performance is achieved. You do need to understand the language, and you need to have memorised the song.

Marje