Paul,
Not sure how discriminating an $18 meter would be. A good app can be pretty amazing, because it often makes use of considerable computing power unlikely to be found in a cheap stand-alone meter. Thing is, the cheaper ones tend to be oriented towards loud sounds. People get them if their neighbor's grunge band or construction noise is too loud.
While sounds from decoders can be loud, relatively speaking, these are sounds that in no way approach that in the class of a 4' high 500 watt bass amp/speaker combo.
But you'll never know unless you try, I'd expect.
I've found the human ear is actually a pretty good judge of such things. Yeah, you'll end up all over the place just punching in random values for the relevant CVs. Use your ear and I'll bet you can end up very close, probably as close as if you relied on a meter. That how I do mine .
Mike Lehman
Urbana, IL
I have a number of locos where I've initially set max volume, engine noise, horn and bell volumes somewhat arbitrarily. And I'm finding, when I run several different types at once, that one type is significantly louder / quieter than another, even at similar loads (high speed, mid speed, horn, etc.)
Thinking this over, and not having noticed the subject before, it occurred to me that a sound meter might help establish better relative loudness. So I looked at Amazon and saw some at only $18. But a buyer's comment then led me to find a (free) phone app, which I downloaded.
Any comments on using these tools as an approach to getting better relative performance? I know one would want to adjust for any known differences (e.g., i presume newer diesels might include some noise reduction??). And there might be some ocos with limitations (e.g., horn output at max). But if I knew a typical loco, in my setting, should be around "x" dB at full throttle, or a typical diesel horn at "y", seems I could preliminarily tune to those starting points, then tweak from there. What I've done before includes gross discrepancies from one to another, so I'm thinking a tool can only help.
Have you tried this, rather than just using the ears?
Paul
Modeling HO with a transition era UP bent