The vowel may also be rather opener, ranging over nʌ or nɑː.
I don’t know of any established way of spelling this interjection, but nuh-nuh-nuh-nuh-nuh or na-na-na-na-na would perhaps do.
I have never seen any discussion of this item in the literature of paralanguage (but perhaps a reader knows better).
It was in my active repertoire when I was a child and — as far as I know — children in England still use it today. Is it also to be heard in other parts of the UK? And in north America and elsewhere? Is it international? Do French children and Japanese children do the same thing?
I raise this issue to celebrate my having at last learnt how to produce musical notation at will for the computer screen. (Some of you may have been familiar with this method for ages, but it is new to me.) The ABC system makes it very easy to write down the score you want. My source file for the above read simply
|L:1/16||unit note length|
|G3 E2A G3 E3||tune body|