Looking at the wording of Sensory Magic on p28 of HoH:MC where it says, "Use the Voice Range column of the Words and Gestures table on ArM5, page 83 to determine the area of effect around the magus."
This suggests the author of this chapter wanted to avoid arguments about how far this particular magic carries, and keep to standard ranges. This is not explicity for Voice Range in Heartbeast, but the Voice range description on p112 of the core book mentions magical enhancements don't affect voice range. It does mention that the distance the voice carries being important - but Bjornaer aren't using normal vocalisations, as they need quiet magic, deft form or to take the -10 penalty for spellcasting without words.
I'm sure I've seen people houserule it as using normal ranges before, but that may be out of fear of munchkin wolves. I'd need to search the forum way back in time, and these boards don't let you search very fast.
EDIT: Here's Doctorcomics thread from 2012:
[url]https://forum.atlas-games.com/t/silent-casting-voice-range-and-bears/6535/13]