All processing happens on your device. Your recording is not uploaded.
What each step does
Noise reduction listens to the quietest parts of the recording to learn what the background sounds like, then turns that sound down everywhere while leaving louder sounds such as speech alone. Loudness evening measures the recording the way streaming services and podcast apps do, in LUFS, and brings it to the level you choose, with a limiter that stops peaks from clipping. Trimming removes silence at the start and end, and can shorten long pauses in the middle.
Questions
Which noises can it remove?
Steady sounds: hiss, computer fans, air conditioning, electrical hum and room tone. Sudden sounds such as a door, a dog or traffic going past change too quickly to learn and stay in. For the best result, leave a second or two of silence at the start of a recording.
Which loudness should I pick?
Podcast at -16 LUFS suits Apple Podcasts and Spotify. Social video at -14 LUFS matches YouTube, Instagram and TikTok. Broadcast at -23 LUFS is the European TV and radio standard.
Will it change the length?
Only if you trim silence. The facts under the result show how many seconds were removed. Turn trimming off to keep the timing, for example when the audio has to line up with a video.
MP3 or WAV?
MP3 at 192 kbps is small and plays everywhere. WAV is uncompressed, best when you will edit the audio again.