Hey there, and welcome to Apple Support Communities, Yanggge!
From our understanding, your right AirPod is making an abnormal noise. We definitely want to ensure you’re able to use your AirPods with ease.
To get started, we’d recommend taking a look at the steps found here: If your AirPods Pro make crackling or static sounds - Apple Support
While the noise that you’ve described is a bit different, they’re great general troubleshooting steps that can help isolate this for you.
If the same thing occurs after completing those steps, try connecting your AirPods to a different device to see if you still hear the same noise. We’d recommend ensuring the device does not have a case or screen protector on it to be sure that doesn’t contribute to the behavior.
If you're unable to resolve this using these steps, Contact Apple Support.
Cheers!