This is why computer geeks always say "backup, backup, backup" đ
If you had set your device to sync over wifi, then your memos may be in iTunes as a backup.
Unfortunately, I do not believe that music and voice memos are part of the iCloud backup unless you arranged for larger data storage and manual storage.
If you subscribed to iTunes Match, all your music would be safe in the cloud but I am not certain about voice memos even though they are part of the music library.
This is why before I upgrade I always make a backup first, and after the upgrade restore I restore from backup to get everything back on the new device.
I hope that you are able to find your files on your computer or at your last backup đ
EDITED TO ADD: But you all are right. This is something that Apple should address.
Message was edited by: matrixxzero