En réponse à Tristan Alexander McLeay <[log in to unmask]>:

> To start off with, Aussies tend to prefer 'umm', and I understand
> Japanese
> 'anoo' (but I could be wrong).

I think you're correct (though I seem to remember that 'anou' is also one of
the ways to say 'sorry' in Janapese).

Moten has a lot of those sounds:
- 'sii' is the literal translation of 'umm', used for hesitation,
- 'aja' marks surprise,
- 'eje' marks exclamation,
- 'ejo' marks astonishment, or asks for a repeat ('sorry?'),
- 'daa' is an encouraging interjection: 'come on!'.

I didn't work on them in other conlangs of mine though.