If a trumpet is enchanted with a voice range, does it work for as far as the trumpet can be heard (about 700 yards) or does it have no range because it isn't the wielder's voice? What about drums? Does the wielder's breath make a difference? For an extreme example, what about a canon? Medieval canons had very little in the way of effective firepower, but boy are they LOUD.
It's important to maintain consistent voices ranges, otherwise you have instances you mention in this example. The best way to maintain this is to use the wielder's voice. The sound from a trumpet is, in essence, the wielder's voice transformed through the instrument. I'd be perfectly fine with using the standard range for shouting (50 paces) for an effect that is activated by blowing into a trumpet. I wouldn't allow it to go any farther, even though the sound can be heard much farther than the magic would carry.
Consider that people can actually hear others shouting from more than 50 paces away, too.
At night, across still waters, you can reputedly here someone from as much as 17km away! And conversely, shouting in a dense forest isn't going to get you very far.
So I agree, keeping voice range consistent is important for ease of play. And sanity. And probably a few other things.
This may be the difference between standard Voice range, and Hearing range: ie, the Bjorner "it's only a mystery because Bonisagus didn't get around to integrating it" virtue. I seem to recall them talking about using the range of musical instruments in that, although I could very well be thinking of something else.
The Bjornaer spectacle mystery was just the thing I was going to make a point about.
Voice Range is a set distance (depending on how loud, but there is a table for this). Other, more noisy methods are currently not supported by the Hermetic Theory, but House Bjornaer have some special methods.
Except that voice range is not constant right now. It is 50 yards if you shout, and 15 if you are speaking normally. I definitely think attributing it to a standing drum would be going to far- that could give it a range of 7 miles (and a early cannon 10 miles) but allowing a trumpet to extend it to 700 yards is still well short of the 5 mile range of sight to the horizon of a 6 foot tall man standing on a featureless plain (obviously from the top of a tower will be further, and obstructions will reduce the range...)
Then use sight range, which also uses the sight of the wielder if distance is so important.
It's not about constancy, but consistency and maintaining some reasonable standard. Magi could turn into lions, should their voice range spells then be able to carry to all who hear their roar? Why is a trumpet reasonable while a canon and drum are not?
Alternately, if you care for some in-game justification, it may be the platonic ideal of how far a clear enunciation of hermetic principles can carry.
This leads to the questíon that assuming you aren't an initiated bjornaer, how would you enchant a musical instrument to affect those that hear it. Thematically it seems a shame to not be able to do it. Would it be voice range but limited to about 50 paces? Or some other method?
I'd suggest that this is something standard Hermetic magic just doesn't know how to do. You can use your voice to activate a magic item, which carries the magic to Voice range; or you can have the instrument magically create it's own sound (CrIm) that, I reckon, carries as far a Loud voice. That's it, that is all the RAW allows ("Magic items use the wielder's voice; independent items need to be given a voice (CrIm) to use this range").
The Mystery of Performance Magic (specifically Sorcerous Music) explicitly allows one to use the Voice range to affect anyone that hears the instrument, even to a very large range. It's a "common" mystery, so I'd say - if you want to do this kind of trick, initiate yourself into Performance Magic (Music) and you can start enchanting away.
Wow. I had to look this up since I could not remember this feature nor believe the solution was so simple...but there it is Mysteries: Revised Ed page 29, "Sorcerous Music" insert box. Good catch.
magic performance drums can get really scary... range can get to 7 miles, depending on drum design...