Audio Level Broadcast quality in Final Cut ProX

My 2 cents as an audio engineer. Audio db leaves are standardized. Voices should average around -6. Everything else should be balanced around that. Don't go much over -3, never hit 0, you'll be fine. It's not about hearing damage, it is about digital audio artifacts ending up in the final mix.

The level meters and the volume db readings are not the same thing. The level of an audio file, at 0, is normal, the level it was recorded at. That can register as anything on the level meter. If I record someone whispering, it'll playback lower. A gun shot will playback louder. But both playback with the "volume" (technically "gain") set to 0, normal. Just like luma levels. Everything imports at the level it was recorded at, then you adjust as needed.

So, for broadcast, if your lowest sounds are averaging -12, your normal speaking voices around -6, and your loudest bangs and explosions averaging around -3, and nothing touches 0, you're broadcast safe. Simple as that. And the Limiter audio effect can be your best friend with problematic audio levels.

Here's a PDF that can help you understand all the audio filters from Logic that are included with FCPX, and how they work.

http://manuals.info.apple.com/MANUALS/1000/MA1651/en_US/logic_pro_x_effects.pdf

Different audio application have different representations for loudness. Too loud in FCPX, according to Apple, is 0dB to +6dB. From +6dB to +12dB we're talking hearing damage. Basically, anywhere you see yellow or orange(red) in the audio signal in the audio waveform, it's getting too loud. That said, sometimes you need loud, so it depends on the sound. The only thing you MUST NOT allow is clipping (audio so loud that it distorts — red, flat peaks.) As a "rule of thumb" -- "normal conversation" levels should be around -12dB to -10dB give or take. Use your ears. Set the mac's system volume level at 50%. Using headphones your audio should be "comfortable" (and clear) at those levels. Let the end user increase the system volume to their liking. If you need to bring intermediate levels up a little, use the Audio > Levels > Logic > Adaptive Limiter. You can limit the overall volume while increasing the gain on quieter signals (it's also a good tool to use to lower the noise floor, if it's not too terribly bad.)

Hope this helps...

PS -- the meters in FCPX top out at +6dB but the volume "bar" in the storyline and the volume control in the audio inspector allows a gain of +12dB.