How to say "I didn't see or hear you"

Welsh General / Questions
#1

I have come across this phrase…I didn’t see you in town…Weles i mono ti yn y dre…I assume this comes from Ni weles i ddim ohonot ti?Is there another way to say this sentence?Could one say Wnes i ddim dy weld?
The same with To hear…eg I didn’t hear you calling me…ni chlywes i chi yn fy ngalw…glywes i mono ti yn fy ngalw…
would be grateful if anyone can clarify.
diolch

#2

Yes, exactly. It’s a construction more frequently used in the South/South West.

Yes, this is fine too.