The answer to 'pressure regulator making noise' is that a noisy pressure regulator is often caused by mineral buildup, wear and tear, or high water pressure. Symptoms may include a loud, whistling or humming sound coming from the regulator, and potentially fluctuating water pressure. To fix a noisy pressure regulator, you may be able to clean or adjust it, but if the regulator is old or severely damaged, it's best to replace it.
For a DIY fix, you can try disassembling the regulator, cleaning the internal components, and reassembling it. However, if you're not comfortable doing this or the regulator is still noisy after cleaning, it's best to call a professional plumber. They can properly diagnose the issue and replace the regulator if needed.