well, the sssssssssshhhhhhhhhhhh noise is when it exits defrost mode and goes back to regular heating cycle. Sometimes it can be louder than others when coming out of a long defrost. If it doesn't always do that I wouldn't worry about that.

The determination of "subfloor" would be part of your contract with the installer/shop. If you PAID for new underlayment to be added (to match the requirements for the floor installed) then you are supposed to get "what you paid for". If the underlayment upgrade was not part of your "job" (you didn't pay for it therefore it is not part of their contractual obligation to do it), then the subfloor that is THERE (in your home) is owned 100% by you. The person who walked through your home and who assessed your subfloor (so they could write an accurate installation quote) is the person who you chat with about the "appropriateness of subfloor material at time of installation". I can't tell you who is responsible for the thickness because I don't know what your job entailed. It all hangs upon the contract for the work. If you paid for new 23/32" OSB subfloor to be laid, then you should have received the product. If you did NOT pay for it, then the condition of the subfloor is, sadly and very frustratingly, on you. Please check the contract and your purchase from the store to find out if your job contained "plywood" of any sort. And yes, some types of nails or staples can make some interesting noises when punched into wood (OSB is particularly upsetting because it can create more noise than others....but if it is the RIGHT OSB then it should be OK). But this is the very reason why many installers avoid OSB like the plague. In this situation it is allowed....but there are many independent installers who won't go near it....for this very reason.

I wanted to provide an update to close the thread. I had the washer exchanged with the same model. The replacement doesn't make any noises at all. The 'load sensing' also takes longer than the previous one with the defect and the drum spins during sensing (old one didn't really sense and turn at all). The defective unit would start sensing, make that weird buzzing/humming noise (which started getting worse compared to the recording) - and then go to washing immediately. Sensing would last a couple of seconds. The new unit senses for much longer and actually turns the drum during sensing. The old one didn't and I though that was normal (never had a front loader). I guess it makes sense in retrospect. This should help the next person that has a similar problem.

It's about 88 degree outside and we have temp set at 78 degree (wife doesn't like to have it set below that!). Temp is being maintained but my house is open with 2 story ceiling from front to back so cold air from upstairs unit also cools air downstairs.. I do feel the only bedroom downstairs is not as cool as it was before (It's got two air vents) when AC was running.