FCPX mono file waveform shows as peaking but audio monitor shows -6db

There are two different reference points in use — one for storyline clips and one for the master meters.

The master meters are set up with a 0dB reference at -6dB from "clipping". Between 0dB and +6dB is considered "headroom" - an allowance for short duration (very loud) sounds that will not clip.

The storyline audio is set up with a 0dB at -12dB from "clipping". Everything over the storyline 0dB considered (too) loud. That suggests that the target loudness peak should be at -6dB in the master meters.

The visual "assist" that FCPX gives you is: you should adjust the audio in the storyline so that none of the waveforms change color to yellow (/orange/red). If you do this simple thing, audio is going to be within the range that is considered "comfortable" to listen to.

Best advice is to put on a pair of headphones, set the System volume to 50% and listen. Adjust the audio to a comfortable listening level and let the end user adjust their volume to their taste. Don't worry so much over the relative 0dB references. They are not the rule — just visual guides to help you make your final decisions.

The storyline audio has a built in volume control - a line you can drag up or down to set the level with visual guides — the color change of the waveform over the 0dB line (relative scale allowing 12dB headroom).

I can't tell from the images what's going on with the Compound clip. I suspect that the original audio has no volume adjustment but the compound clip level has a +4dB volume increase. The actual clip (inside the CC) shows its unadjusted waveform. The effect of volume adjustments to a compound clip are *additive* to any adjustments made to the audio contained within the CC.

The storyline scale is always going to be the same for all clips in the storyline - the 0dB reference is -12dB from clipping. It doesn't change for compound clips. The general recommendation for audio at the master level is set the loudest sounds (barring sound effects etc.) to no more than -6dB on the master scale (loud music, usually heavily compressed). Regular conversation levels at about -16dB to -12dB, give or take. The storyline audio controls are an attempt to simplify making these decisions by providing color information for peaks that are, in general, considered **too loud** (potential hearing damage). Trust it. It's really quite good especially for people who are not audio engineers (and that's almost everybody!)

I've noticed this too. The wavform in the storyline is always hot compared to the master meters on the side. I usually just ignore the storyline one and go by the meter on the side, keeping it below 0db.

Great advice, I did not know about the difference in setup with the meters. So strange, why would it be this way?

Also, what does that mean for the compound clip? yalcincoban in the OP says:

"When I turn the audio into a compound clip the waveform displays correctly and there is no change is audible sound."

That would lead me to believe the compound clip is using the same 'setup' as the master meters, why is the storyline different?