Historically that sound would have been a loose belt and/or debris on the fan. But given modern auto-belt tensioners and electric fans it's now more difficult to ascertain. But still do check, as much as you can, dirt/sand/debris around the belts, pulleys and fan blades. With care not to wet electrics/connectors a low pressure engine bay wash can often help, with appropriate cleaner if needed.
Also look for any loose plastic parts that may be intermittently rubbing.
If the noise continues when clean then it is most likely belt/pulley related.
btw: does the noise quiet when the engine is fully warmed?
Thanks. The noise seems the same whether the engine is cold. or warm.
I'll attempt to clean the engine bay today but need to find YT videos on which electrical parts need to be covered and the best way to accomplish that. Alternator/fuse box/ battery, anything else? Tape garbage bags around it?
Yes, good YT insight. I wouldn't bother disconnecting the battery, just cover the lugs and keep water away from that area anyway. One of the reasons for low pressure water is that you don't want to inadvertently drive dirt into an electrical connector (that you forgot to cover). I cringe when I see folks take a pressure washer to a modern car. A lot can be done by hand and then just a mild rinse.
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