Why "mid-bass"? "Deep bass"?

[herbu]

I see these terms used a lot in subwoofer comparisons and analysis. But I think of a sub's performance from ~15Hz > ~200Hz.
With a widely used crossover of 80Hz, the range is ~15Hz > ~160Hz.
LFE is defined as 3-120Hz.

So we have a speaker, usually with a single driver, and about a 200Hz range.
In a regular speaker, I think the woofer has a much wider range.

Why do we have to split the relatively small 200Hz range into even smaller segments like "mid" and "deep"?
It seems strange we can talk about 50-20kHz in a $100 speaker, yet need to split characteristics of a $1k speaker into frequency ranges so narrow.

 

[Steve81]

It's a small range in terms of Hz, but not small in terms of the number of octaves represented, and the differences in how those frequencies are perceived.

 

[shadyJ]

Consider the physical differences between the frequencies. A 10 Hz sound is ten times longer than a 100 Hz sound, which is 10 times longer than a 1000 Hz sound, etc. For every octave lower a woofer has to play, its excursion must increase four-fold. Consider how much space the subwoofer band eats up in this logarithmic scale of sound waves:

Keep in mind humans perceive sound in a logarithmic manner much more so than linear.