How Fade In/Out Works
A fade is a gradual volume change applied to the beginning or end of an audio file. Fade in starts from silence and ramps up to full volume over a set duration. Fade out does the reverse — it gradually reduces the volume to silence at the end of the recording.
The fade curve is applied mathematically by multiplying each audio sample by a gain factor that changes over time. At the start of a fade in, the factor is 0 (silence); it smoothly increases to 1.0 (full volume) by the end of the fade duration. This creates a natural, artifact-free transition that sounds professional and polished.
Unlike hard-cutting audio (which produces audible clicks and pops), fading eliminates transient artifacts entirely. The processing is lossless in nature — no re-encoding, no quality degradation. Combined with WAV output, you get uncompressed audio with perfectly smooth transitions.
Fade Duration Guide
| Duration | Fade In Best For | Fade Out Best For |
|---|---|---|
| 0.5 s | Removing mic click/pop on Voice Memos | Quick cutoff smoothing |
| 1 s | Standard speech recordings, interviews | Eliminating stop-button tap on Voice Memos |
| 2 s | Podcast intros, gentle start | Natural speech ending, meeting recordings |
| 3 s | Music intros, ambient recordings | Song outros, background audio loops |
| 5 s | Cinematic builds, long ambient intros | Dramatic endings, meditation audio |
Tip: You can set fade in and fade out independently. Use 0.5s fade in with 2s fade out, or any combination that fits your recording.
M4A to WAV Fade: Voice Memos and Apple Recordings
iPhone Voice Memos are the most common M4A files that benefit from fade effects. The M4A format (AAC-LC codec) preserves audio quality well, but recordings often have abrupt starts and endings — a microphone pickup click at the beginning and a tap sound when you hit the stop button. Converting to WAV with fades solves both problems in one step.
Voice Memo Cleanup
When you tap the record button on iPhone, the microphone activates with a brief transient — a click or pop that appears in the first 100–300 milliseconds. Similarly, tapping stop creates a subtle thud at the end. A 0.5s fade in cleanly masks the startup artifact, while a 1s fade out eliminates the stop-tap sound. The result is a professional-sounding recording without manual editing.
Podcast Episode Editing
Podcasters who record field segments on iPhone often need to splice M4A clips into a larger project. Adding a 1–2s fade in and 2–3s fade out before importing into Audacity, GarageBand, or Logic Pro makes transitions between segments seamless. The WAV output ensures no quality loss when the DAW processes the file further — no generation loss from re-encoding compressed audio.
Interview and Meeting Recordings
Meeting recordings captured on iPhone frequently start mid-sentence (you fumble to hit record) and end abruptly when someone stops the recording. A 1s fade in softens the jarring start, and a 2s fade out creates a natural conclusion. Converting to WAV gives transcription services like Otter.ai and Whisper the highest-quality input, and the fades prevent speech-to-text errors caused by transient artifacts.
Voice Memo workflow: Record on iPhone → AirDrop M4A to Mac → Upload to Convertio with 0.5s fade in + 1s fade out → Download WAV → Import into your DAW for editing. The fades are baked in, saving you manual envelope work.