What's "ching" in the song "Bike" by Pink Floyd?

[CRAZY-HORSE]

here's the lyrics if anyone's interested:

PINK FLOYD "bike"
I've got a bike. You can ride it if you like.
It's got a basket, a bell that rings and
Things to make it look good.
I'd give it to you if I could, but I borrowed it.

You're the kind of girl that fits in with my world.
I'll give you anything, ev'rything if you want things.

I've got a cloak. It's a bit of a joke.
There's a tear up the front. It's red and black.
I've had it for months.
If you think it could look good, then I guess it should.

You're the kind of girl that fits in with my world.
I'll give you anything, ev'rything if you want things.

I know a mouse, and he hasn't got a house.
I don't know why. I call him Gerald.
He's getting rather old, but he's a good mouse.

You're the kind of girl that fits in with my world.
I'll give you anything, ev'rything if you want things.

I've got a clan of gingerbread men.
Here a man, there a man, lots of gingerbread men.
Take a couple if you wish. They're on the dish.

You're the kind of girl that fits in with my world.
I'll give you anything, ev'rything if you want things.

I know a room full of musical tunes.
Some rhyme, some ching. Most of them are clockwork.
Let's go into the other room and make them work.

Songwriters: SYD BARRETT
Bike lyrics © T.R.O. INC.

very childlike to me...
very nursery rhyme-ish in a very British way to me....

i read the 'ching' as being a nonsense word, like you would find in a lot of children's songs,
i dont read too much into it...
over analyzing lyrics to the point of disecting them and turning them inside out is pointless...just listen to the track ARTYOM and enjoy it(or discard it)....
and it is well documented that Barrett was almost always 'high' on something,so what made sense to him whilst 'under the influence' probably didnt on the odd occasion he was 'back on planet earth'....