system
Given the following post, respond as if you're commenting on Reddit:
human
Why do faucets hiss at specific levels of valve-openness, which seem random and nonlinear?

It seems really unusual - when the faucet is barely open, it doesn't produce the sound, and it doesn't do so when it is fully open. However, at about 1/4 and 3/4 open (but not at 1/2), there are two levels when it produces a loud hissing sound. How can this be explained? Why is the pattern so nonlinear? Is this something about turbulence?
gpt
Its more about resonance in the faucet. Consider a violin string that resonates a tone when the bow is drawn against it. In the faucet the water is the bow, the faucet parts are the string. At the right amount of flow the faucet resonates producing the "hiss" sound you hear. Its a standing wave or vibration of the assembly.  Grab the faucet when this happens. Does the hiss change or stop? You altered the mass of the faucet by adding your own, effectively lowering the resonant frequencies . Sometimes it is the faucet, other times the washers or other internal parts.