Please tell us some basic information before asking for help:
Model Name: Zenfone 9 16/256GB
Firmware Version: WW_32.2030.2030.26
Rooted or not: Not
Frequency of Occurrence: Intermittent, daily
APP Name & APP Version (If your issue relates to the app): Unrelated, system wide
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
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Sometimes when receiving a notification and typing at the same time, the lower speaker of the phone will emit a loud pop/crackle/snap noise. This can also be replicated by going into an app like the photo gallery or contacts with a long vertical scroller, and scrolling rapidly up and down using the quick scroll-to-date or scroll-to-letter functionality at the side of the screen. It seems like it occurs when two vibration events are meant to occur at the same time.
I was able to reduce the frequency of this occurring slightly by reducing the vibration power in settings, but it still persists intermittently as before.