I was recently in discussion with a client about his album of spacey, dynamic, almost modern classical, electronic, ambient type material, and his concern about track to track level. I wrote a whole long rant about loudness and albums, which I thought some people might enjoy reading.
For a start, RMS is pretty bad as a measure of perceived loudness. It’s a mathematical measurement of power in a system, has nothing to do with the human ear, and doesn’t take into account frequency response or dynamics like the human ear does. Bass frequencies have a much higher RMS than treble frequencies, so a bass heavy track may read far higher on an RMS meter, while subjectively sounding much quieter. The new LUFS loudness standards are a step in the right direction, (taking frequency response more into account), but still don’t correlate particularly well to perceived loudness in the room, on many occasions, and were designed with Film, TV and Radio broadcast in mind, more than for serious music listening.
I usually get a “ballpark” figure going while I’m mastering, from track to track, using Integrated BS.1770 LUFS on just the loudest sections of a particular track, so that those sections are all within about 1.5dB Integrated LUFS of each other. (The actual figure I use will depend on the artist’s wishes and genre etc. What might work well for an ambient album would probably be considered way too quiet for my Hip Hop or EDM clients, for example). When every track has been mastered I go back to the whole album from start to finish and fine tune the levels by ear, because ultimately that will be the experience of the end listener. It has to sound good and flowing and coherent coming out of the speakers in the room at various different volume levels, for best translation across a wide variety of systems. I’ll also do a final QC listen on headphones.
That brings me on to the next point, which is track order. If the order is set, then that’s the order I work with, trying to make sure all the tracks flow well together, one into the next. This includes timbre, loudness, and “gapping” (the length of silence between each track). I will not focus extensively on A/Bing tracks next to each other that are not next to each other on the album. I might do so more for an album where the artist has requested it be more like a “collection of singles” than an album, or are concerned about wanting it as loud as possible overall, or that all tracks will sound similar in a randomised playlist etc., but this is not usually a request when I work on proper “album as album” projects.
I think you have to decide if you want an album where every track will sound at a similar level next to all the others, or if you are happy with a bit of dynamic ebb and flow between tracks for a better “album feel” and contrast. For me personally, Ambient albums usually benefit more from the latter approach. I can advise, but ultimately the creative decisions lie with the artist and their vision, and I will try to fulfil that in the best way I can. Overall volume changes are a pretty quick and easy tweak, as it’s mostly done in the final stage at the limiter, just before render, so it’s usually not too much work to make any changes required.