Hello, Themaumau.
Thank you for visiting Apple Support Communities.
I understand that you have concerns regarding a Find My iPhone request that you received. This sounds like you may be part of a Family Sharing account. Anyone who is part of your Family Sharing account can play a sound on a family member’s device. You would have to check with the members of your Family Sharing account to verify who sent the sound. Also, an email confirmation is sent to the initiator once a sound is played. For more information on this, take a look at the article below.
iCloud: Play a sound on your device
Cheers