Advice on water pipe sizing.

Have had this house for two years now. One thing that is really bothersome is, my roommate takes two baths a day - which I don't mind - but the pipes are very noisy 90% of the time; I'm pretty sure if she opens one or both of the valves fully, there is sort of an air'y noise, but if she doesn't open the valves all the way it's not that noisy, just the sound of water running. If it makes a difference, there is a hot and cold valve that you turn to the left separately. The rare times that she does take a shower, it's only a soft water noise, like in my shower. It's hard to describe the noise without hearing it, but here are the two ways it sounds, the first being the soft one and the second being the noisy one: Soft: "ffffffffffffffffffffffffffffffffffffffffff" Loud: "SHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!" Unfortunately, my bedroom is next to the bathroom and the copper pipes are between the wall. I tried putting some sound isolating batting but it barely helped, and still wakes me up every morning and night. I asked her to open the valves to where it isn't noisy, but she keeps forgetting so I've given up on that. I tried googling some remedies, but most talk about "air hammer" which I don't think this is. Not sure if it makes a difference but the bath is on the 2nd floor and the water stuff is in the basement. Any ideas on what to do?

Forgive me. I was an English major and tend to accidentally do long posts. You have been warned. I live with my roommate in a 2 story house built back in 1941. A while ago the biggest of my 2 1/2 bathrooms started leaking into the kitchen below. My dad and I hired a plumber to come in to fix the leak. They took out the ceiling in the kitchen and replaced all the pipes, but that hasn't stopped the leak. We have determined it's not the new pipes leaking. The water is now leaking through the floor and is isolated to just the shower. My "big bathroom" has a large section where the toilet, sink, and bathtub are located and a separate closet style shower as another section. I hope that makes sense to you guys. Our plumber recommended another person who specializes in tile to help with the new leak. He came in and determined the old cracked tiles were indeed the culprits. Dad, who is paying because I don't make enough money to do anything other than pay bills, had his heart set on one of those Bathroom Fitters. I'd rather stick with tile. I'm skeptical about the Band-Aid approach of the Bathroom Fitters, so I inquired about cost effective alternatives to that and to completely, and expensively, retiling the bathroom. The "tile specialist" suggested a spray sealant. We also discussed panels, which he said would probably cost about the same as re-tiling. I like to know what I'm dealing with. I don't like being blindsided, so I took it upon myself to do extensive research on bathroom building techniques from the 1940s and what's done differently today so I could have an intelligent conversation with both this guy and my dad about the topic and actually know what's going on. Many people have now told me I've done so much research I probably know about as much as this guy does at least in theory. Well, I turned Dad. He accepted the spray sealant approach and ditched the Bathroom Fitters idea. I informed the contractor that this is the approach we wanted to take and he said he would get back to me with an estimate. A week later I asked him if he'd forgotten about me, he said he was still figuring things out. Two weeks later, I asked him if he was too busy if he could recommend someone else and he did one of my biggest pet peeves. The "Silly woman tricks are for kids" patronizing laugh really grates on my nerves. It makes me do stupid things like try to do it myself. The contractor said he wasn't comfortable with the sealant method because it's a temporary solution. Then why did you suggest it before? He, then, suggested the panel idea, which before he said would cost about the same amount as tile. Dad has already said we don't have the money to retile the bathroom. Needless to say, I haven't heard from the tile guy since. Now, eventually I would like to completely redo the bathroom with new paint, new tile, new fixtures and, if I can, a more energy efficient window. Looking up from the kitchen, I don't see any significant water damage from the wood sub-structure framing, nor any signs of mold. Right now, my main concern is the shower only. Would I be able to remove the tile and expose the wet-bed in the shower and leave the rest of the bathroom for a later date, or would I have to do the whole thing all at once? Would a spray sealant be a decent temporary fix to get Dad's involvement out of the way at the very least, so I'm free to dig in myself later? The tile guy said the glaze on the tile would make it impossible to get the sealant to stick. Wouldn't texturizing the surface of the tile with, say a file, help the sealant to stick better? Dad also mentioned the most expensive thing with redoing the tile in a bathroom is installing a layer of stone slate to support the waterproofing under the tile, but I have a book copyrighted 2011 that has no mention of stone slate as one of these under tile support layers. Does that mean society has developed more cost effective alternatives to the 1980s stone slate layer Dad is referring to? Is there any other information anyone can give me regarding this dilemma? I just want to get this done. It's been over year since we removed the ceiling in the kitchen and I'm ready to be done. Thank you in advance for reading my long and probably confusing post, and thank you for any information I can get.