Ohhhhh I've seen that one, I love that video!! Most beautiful lady ever...her voice is so lovely.
I actually happen to know how, um, not as great German hymns would be! I used to sign with a choral group and those germanic hymns were just kind of difficult. I suppose learning them as a non-german speaker made it hard...but they didn't realy flow or seem liquid and really "musical" as some of the other languages.
Have you considered making your own? Making a melody that is easy to repeat and easy to sign, that is in tones that sort of fit your kind of "birth hum". I know for me, my birth hum tends to be very low and sort of constant...so lower, longer toned melody would be great for me...maybe after you make a simple little melody, you could come up with a birth mantra for yourself that lifts you up and makes you feel good...and then put the mantra to the melody and use that as your birth son??
Like, my birth mantra (which I didn't repeat to myself the whole time or anything, but definitely loved and used somewhat in my first labor, was something that a mama here at MDC posted as a good birth mantra:
I am whole, I am peaceful, my body knows and does it's perfect work.
I swear, so long as I'm breathing, there is nothing I could do to forget those words! I made a beautiful little sign with those words on it and decorated it and everything and hung it up in my kitchen for my pregnancy and it was so special to me.
There have been some REALLY awesome threads over the years here on birth mantras....you could even make or pick a birth mantra and put it to the melody of a song you know well, some simple nursery rhyme, something easy to remember and get lost in that you've known since childhood or something and just know to the depths of you. What do you think?