An audio recording can either be analogue or digital. It is a recorded version of a live audio event. Most of the audio recordings we use in audio forensics are spoken word or dialogue. Some of the recordings audio forensic experts analyze include confessions, sworn statements and calls for help like 911 recordings.
Analogue recordings are stored on magnetic tape. Digital recordings are stored on sd cards of other memory devises like a chip. Digital recordings can be cloned where as analogue recordings can only be copied.
Original audio recordings should be used as evidence, not copies. This removes any doubt as to their authenticity. Copies of audio recordings can be modified and go undetected.