Originally Posted by Shadowed
What frequency ranges are considered sub-bass, bass, and mid bass ?
Which ones are more important for movies vs music listening?
Different people will inevitably define the bass frequencies in different ways. One comprehensive definition of bass frequencies is offered in the Section of the Guide I am linking below. I think you may find the detailed discussion helpful.
Briefly, I would define bass frequencies as starting at about 500Hz, where the Equal Loudness Contours show our hearing start to change. I would define mid-bass frequencies as starting at about 120Hz where the Dolby/THX standards originally pegged subwoofer frequencies, and continuing down to about 50Hz, which is the lower range for chest punch sensations. And, I would define very low-bass frequencies as starting at about 30Hz.
(To make things a little more confusing, ULF is typically defined as starting at 20Hz. And, that 20Hz frequency was originally the lower limit of the Dolby/THX standards.)
The article I linked also attempts to distinguish between the bass demands required for most music, and the demands required for 5.1 movies. In general, the special effects in movies place more demands on subwoofers, below about 35Hz or so, than is found in most music. In addition to the lower frequencies found in many movies, the LFE (low-frequency effects) channel is recorded 10db louder than the regular channels.
Subwoofers which attempt to reproduce movie special effects, at significant sound levels, not only have to play lower than they would for most music, they also have to play those lower frequencies at louder volume levels. So, although all bass frequencies are equally important in one sense, some frequencies may be more meaningful for movies than they are for music.
There! That should be as clear as mud now.
But, the more detailed explanation may help a little more.