The voice-recovery seen on television programs like CSI is science-fiction: not possible in reality.
The recovery is Hollywood, but a conversation capture isn’t.
This is an Olympus TP-7 microphone. You jam it in your ear and park your phone on top of it. It picks up both sides of the conversation. I use it with a landline phone, but it works with a cellphone, too.
There is a caution. If you record on the computer, the recording has to be the only job the computer is doing. No fair trying to record a Zoom, Skype, Meeting, Chat or other performance on the same computer.
Zoom, Skype and most others will record a call for you on their servers if you ask nice. This recording thing came up quickly when the services got popular.
my question was if it’s possible to transform my recorder in something much better
but if i well understood everybody my last interview is good to put in the trash because we can’t improved it with audacity ?
There’s no recovery for that posted presentation. Even the Hollywood cheat of getting actors to say the words in a studio wouldn’t work because some of the words are missing. That was the last possibility.
If you decide to use a service or App, use one that produces recordings on a server or system other than your computer. As I posted, both Zoom and Skype (last I checked) would record the conversation for you and present you with finished sound files.
You almost always have to have two “things” to record conversations. Your computer and the Zoom servers, a phone and a recording computer, Cellphone and a separate sound recorder. Trying to do everything on one computer (or one cellphone), which seems like a good idea, almost never works.
There is a side issue as well. Recording private conversations is actually illegal in some countries. That’s why calling tech support always has that message: “This call may be recorded for quality control or training purposes”