Hi Worfzara,
Always use the "C" weighting scale for all measurements of reproduced music levels at home, live music SPL measurements and outdoor measurements of any kind of industrial sound levels or live concerts. The "C" weighting takes into account bass frequencies, whereas the "A" weighting scale suppresses the importance of deep bass.
I can't recall if there is a "B" weighting or what it represents. I've never come across a reference to it in all my years writing about and reviewing audio components and loudspeakers.
Regards,
Alan
