Here are some options, depending on the context:
For general sounds:
* "Ugh" - A common way to spell a grunt or a groan.
* "Mmm" - A soft, pleasing sound.
* "Ahh" - Can be a sigh, a gasp, or a sound of pleasure.
* "Oomph" - A forceful sound, like a push or a punch.
* "Shhh" - A sound of silence or hushed tones.
* "Whee" - A sound of excitement or something moving quickly.
* "Thump" - A heavy, dull sound.
* "Click" - A sharp, brief sound.
* "Brrr" - A sound of cold or shivering.
* "Zoom" - A sound of fast movement.
For moans:
* "Moan" - The most basic and direct spelling.
* "Groan" - A deeper, more guttural moan.
* "Whimper" - A soft, weak moan.
* "Sob" - A moan accompanied by crying.
* "Sigh" - A soft, breathy moan.
* "Pant" - A rapid, heavy moan, often associated with exertion.
Onomatopoeia:
These spellings are called "onomatopoeia," which means words that sound like the noises they represent.
Ultimately, the best spelling depends on the specific sound you want to convey and the context of your writing.