Sounding, well female sounding is very interesting and has a long history.
I actually spoke about it at an event recently, and actually one of the educators stated that you can't perform it by mistake, but this isn't 100% true. When reading through medical articles, in the early 1900, a few people had performed sounding by mistake. Part of the reason was due to the lack of sex ed, but also some women just enjoy it and went from there.
With female sounding you must remember that the uretha is a lot shorter in women than it is with men, so using a sound with a stopper is very important, as thingscan be pushed inside the bladder.
With female sounding there's very fewe devices designed for women, but when chatting and working with people, the thicker the better. So something about the thickness of a chopstick is meant to be more comfortable than when usings a thinner item.
While I have performed and taught about male sounding, I'm unable to comment on how it feels, but the guys seem to enjoy it a lot when performed cdorrectly.
I have tried this myself recently, as part of my quest to find something really special to replace the lack of real intercourse.
As a young teenager (14) I had an exploratory camera inserted as far as my bladder. In those days, of course, technology was not what it is now, and that was as far as they could go. These days they go as far as the kidney! But the one memory I had from that was coming round from the general anasthetic and when I went for a pee it was like passing broken glass for about 5 days after. So, needless to say, when I first heard about sounding (through this forum btw) I thought, OW - how CAN that be a pleasurable experience?
But I'm game for anything - after all, how can you knock something if you haven't tried it? So I bought an 8mm Rosebud sound knowing that I could easily deal with that as I had been stretched by that operation. I was very tentative at first and took it very slowly. Of course approaching it like this didn't actually give me any pleasure as I was more concerned with the possibility of after effects like I had before. But I have practised, and can now get right down to the prostate and massage that, and I must say that the feeling is really quite nice.
As nice as it is, I don't think it will ever bring me to an actual orgasm, so I'm exploring other alternatives now. But for preliminary play within a couples relationship I think it would be really nice, as it definitely increases the sensitivity for the man which (and as you know I can only guess here) would make penatrative sex afterwards really great.