Random Voice Memos

Hi. I recently bought an iPhone 11 and there is three voice memos that I didn’t take, and two have been taken before the iPhone 11 was even released, on March 9, 2019. The third one was taken on the 28th of June 2020. They’re all titled “New Recording”, “New Recording 2” and so on. The first two are of some concert thing, with voices and babies cries audible. The third is pure silence with some weird thumping noise. The third goes for around three minutes, the first two around 1.5 minutes. Any ideas what this is?