Marco Arment, on the recent major update to Overcast:
Since Voice Boost is mostly about high-quality volume analysis and loudness normalization, I went straight to the top, implementing the ITU BS.1770–4 standard that gives us the LUFS measurement seen in high-end audio editors. […]
Voice Boost 2 normalizes all podcasts to –14 LUFS — a level I chose because it closely matches the volume of Siri and most iOS turn-by-turn navigation voices, so when you’re listening to a podcast while driving, navigation interruptions are less jarring.
Most professionally produced podcasts are already mastered to similar volume levels, so Voice Boost 2 won’t overcompress them with aggressive processing — it’ll only apply as much correction as necessary to make them all the same volume.
I never used Voice Boost prior to this update, I just didn’t like how it sounded. But this update is absolutely fantastic, I forget I’m even using Voice Boost at all. When I toggle it, though, I can really hear the difference — especially on podcasts with lower production quality.