Audio Fades: When, How Long, and Which Curve
A fade is the smallest audio touch — lifting volume from zero and easing it back — yet choosing the right scene, length and curve is the cheapest step between "raw recording" and "finished".
Four cases that deserve fades
Music in and out: BGM entrances and exits with 1-2 second fades so voice never gets slammed or yanked. Cut ends: a trimmed clip usually starts or stops mid-waveform — add 0.3-0.5 second micro-fades to kill the click. Loops: short fades at both ends make the loop point inaudible. Emotional endings: 2-4 second long fade-outs give closure to music and podcast tails.
The cases that do not: spoken dialogue and interview bodies — fades make speech sound breathless; material that must sync to video — a fade moves the effective start point.
Duration guidelines
The universal 2-second default suits music endings. Finer calibration: click removal 0.3-0.5s (longer starts eating words); music in/out 1-2s; emotional sign-off 3-4s; ambient beds can go 5s+. The tool default of 2 seconds with a 0-10 second range covers most scenes out of the box.
A practical trick: when unsure, apply 2 seconds and listen — too soft, halve it; too abrupt, double it. The ear beats any formula.
Choosing among four curves
Linear: volume changes at a constant rate — plain, functional, fine for testing. Equal-power sine: smoothest loudness perception at the midpoint — the first choice for crossfades and music in/out, since overlapping material sounds most natural. Half-sine: a gentler build, suited to atmospheric beds. Logarithmic: fast start, slow settle — for openings that arrive quickly without harshness.
When unsure, pick equal-power: it is the universally best-sounding default, and for crossfades its constant-midpoint-loudness property prevents the "volume dip" at the handoff.