I use sounds all the time. She is using a Van Buren which is intended to go into the bladder, which means it goes throung the prostate. This is the most enjoyable feeling when sounding. I would never let anyone (other than a doctor) use a Van Buren on me. There are some curves you have to make and it is best you do it yourself.
Dilators are designed for stretching; sounds are designed to go down an existing opening to open up a blocked urinary tract. Sounds are not supposed to be used to stretch the tract due to the physical nature of the device...the curve. It was invented a few centuries ago if my memory serves me correctly to open up the urinary tract so men could pee. The tract either swole up or was blocked by scar tissue due to a sexually transmitted disease. Sounds are great for urethal play if inserted by a top (dom) before an erection is obtained by the bottom (sub); and they should be removed only after the erection has subsided. If one wishes to be stretched open, then use a set of dialators...that's right, a set. Sounds are sold individually. There is no such thing as a set of sounds that is sold by a reputable distributor; only dialators are sold as sets. Anyone with a medical degree or anyone who has been around correct urethal play will inform another that a great quality sound (one made of 316 low carbon [316L as it is known]stainless steel) is sold as an individual item.