When you delete a synced voice memo from iTunes, it stays on the device where it was recorded, but is deleted from any other iPhone or iPod touch you synced. If you delete a synced voice memo on iPhone, it's copied back to iPhone the next time you sync with iTunes, but you can't sync that copy back to iTunes a second time.

Sync voice memos with iTunes. Connect iPhone to your computer, then in iTunes select iPhone. Select Music at the top of the screen (between Apps and Movies), select Sync Music, select "Include voice memos," and click Apply.

Voice memos synced from iPhone to your computer appear in the Music list and in the Voice Memos playlist in iTunes. Voice memos synced from your computer appear in the Voice Memos app on iPhone, but not in the Music app.