Assessing volume and loudness for the sake of normalization without actually hearing the signal?

Question

I'm primarily a guitar player and play through some fancy digital equipment to make me sound less awful. One of the nice things about this kind of gear is you can have many different patches, each one a wonderful different sound. The down side to this approach to making music is you have to spend time normalizing the levels of the patches. So switching between patches doesn't result in any giant jumps up or down in volume.

In the past I'd do patch normalization the old fashioned way: I'd set up my rig, turn it up to near-gig level, fire up my SPL meter, throw in my ear plugs, and play through my patches. Trying to match SPL levels from patch to patch and using my ears to fine tune the levels.

Those days are over for me. I rarely have an occasion to turn my rig up to gig volume if I'm not at a gig or a rehearsal. So I'm trying to come up with a workflow for normalizing my patch volumes that doesn't require me running my rig amplified at gig volumes. It's an all-digital rig, so I can run it silent and straight in to my Mac.

My question is: can I properly assess the amplified volume of my patches without actually amplifying them? Is there a metering or visualization solution that can help me figure out the right volume levels for each patch?

Standard peak meters or VU metering seems overly simplistic here. Peak power and perceived volume don't always correlate which is why I've always done level setting the way I have. Low-volume monitoring for level setting doesn't work well because of Fletcher-Munson effects -- I'll be compensating for the low-end frequency loss.

Some restrictions:

• I can use headphones for monitoring but I'm pretty careful about my hearing so my headphone use is generally low-volume use.
• I can use near field monitors but same deal: low volume monitoring only. Low enough that talking over the monitor level can be done quite easily.
• Any metering or visualization solution has to run on an Intel Mac running Lion.
• I have Logic 9 at my disposal if that helps.

Answer 1

I wouldn't rely on any kind of metering if I were you. Different sounds need different levels to properly fit in the mix, and the only reliable way to tell is to actually hear the sound together with all other instruments. So the "old-fashioned way" is just the right one: set up the levels on rehearsals with the whole band. It can't be that time-consuming to modify and save the master level of a patch! At least, if it is too time-consuming then there is something wrong with your setup.

If, for whatever reason, this isn't an option for you (as seems to be the case), then I'd at least try to simulate the actual live situation, by making a dry record of some representative songs with the band without your guitar, with a simple room microphone of a mobile recorder located roughly where you stand when playing the guitar. Then, at home, play your parts on top of this and fit the sounds as if you were preparing the stuff as a studio record^*. You can do this at (reasonably) low levels: it will sound different from the proper levels, but that doesn't matter because the "right" sound is never defined by how the guitar sounds on its own (except in e.g. some FX-laden guitar-only intro) but only by how well the sound fits in the mix, and for that the Fletcher-Munson effect isn't all that critical because it will affect all instruments, which your ears will to some degree adapt to. Of course, you should use monitors that properly cover the whole frequency spectrum.
There is one problem with this solution: the global frequency response for the band backing track won't really match the live situation. So if you then compare it to your directly monitored guitar sounds, the frequency responses won't match properly. The way to solve this is somewhat hackish: also record some simple guitar part with the mobile recorder, played through your live monitor. Then, before starting to set the levels, record the same part through your direct digital setup. Put an EQ plugin on the mobile recorder track and set it up in such a way that the frequency respone is roughly the same (control with an analyser plugin). OR, if you actually use a clean guitar amp as your live monitor (in which case it isn't an all-digital setup!), do it the other way around (EQ on the direct guitar track to match the recorded sound); or EQs on both tracks.

When you've gone through this process and modified your patches so they fit in the mix you may notice that some of them will sound rather worse on their own than they did before. That's not a bad sign: sounds that fit well in a mix often don't sound particularly interesting on their own. Vice versa: I hate digital effects which produce one hell of a sound on their own, but float away like thin mud as soon as you're playing with a drummer.

^*But of course without extra studio effects!