A new housemate likes to end her warm showers with a run of cold water. We've noticed there is a very loud whining/foghorn noise after she switches from hot to cold water, for the duration of running the cold water. I've read online about banging/pulsating noises when using hot water, but I don't think this situation is the same.
More detail: The housemate switches the shower settings from hot/warm to cold (the coldest setting) instantly, and our shower manages to change temperature with about a one second delay. The noise usually begins after that second's delay (i.e. as soon as the very cold water comes on), and lasts the duration of the cold water usage. It stops as soon as she turns the shower off completely. The noise does not seem to come from the shower head but from the pipes system itself. There is only a temperature knob for the shower, and no power setting.
Can anyone figure out what is going on and I'd be extremely grateful for quick fixes if there are any (aside from making her change her shower habit!). Thank you!