Budgie making "spitting" noises

by Lizzie
(New Zealand)

Hi there, My green and yellow budgie has started making (what sounds like) spitting noises. He makes like 6 ot 7 of these noises in a row and then will go back to whatever he's doing.

Before he makes these noises, he seems to look like he's chewing something (eg his beak moves up and down), but most of the time he's no where near food when he makes this noise.

Please can you help?

Cheers!