There are not many pure backwards recording programs. You can see that some of them are backwards converters. What if you want to record your sound and system audio in reverse simultaneously? During this time, you can use Vidmore Screen Recorder to record any audio from your computer or internal/external microphone. Later, you can save audio recording files as MP3, M4A and other formats without quality loss.

Vidmore Screen Recorder
Record system sound and microphone audio simultaneously or individually.
Adjust audio format and quality based on your need.
Set hotkeys to start, pause, resume and stop recording internal or external audio.
Set a scheduled task to record audio or video automatically.
No maximum time limit for audio recording.
Trim your audio recording file with custom start and stop time.

If you don’t need advanced audio recording features, Vidmore Free Online Audio Recorder can also be your good choice. You can record audio on your computer for free. It is 100% safe and free to use. Though the hardware speedup, adjustable audio quality and other tools are not available in the online tool.

Top 5 Backwards Recorders for iPhone, Android and Online: https://www.vidmore.com/record-audio/backwards-recorder/#part1