sound from running water pipe

some noise comes from inside of 1~1.5" water pipe in my house's basement during water running period, it's like "PHeeeeeeeee" constant level pitching sound, pipe is brass one, is this normal? or something wrong? I noticed this phenomenon two months ago. thanks for your advices.

It may be a bad PRV valve.
Or you may eant to check to make sure the shutoffs for lavs, sinks and toilets are opened up.

when I approach my ear to water pipe, sounds coming from inside of pipe, but only noise during water use, IOW calm when no water use....weird...