You can look at audio spec sheets all day long and never really learn anything. Ninety percent of speakers, amplifiers, headphones, microphones, and other sound producing or receiving devices list their range as 20 Hz - 20 kHz without much explanation or clarification. That range is generally described as the limits of human hearing. I’ve been to too many concerts to hear anything quite that high, but now that I wear earplugs at loud concerts or when I’m vacuuming or mowing the lawn, it’s hopefully not getting dramatically worse. Except that as you age you tend to lose some hearing anyway. That’s why you always have to speak up around Grandpa.
What the specs don’t usually specify is what the drop-off is in volume as you get to the extremes of the frequency spectrum. When it’s listed, it’s usually done as something like 75 Hz-20 kHz +/-3 dB. That +/- part is the fudge factor and can make the range specified relatively meaningless. So when you’re buying speakers you have to actually listen to them first. This is hard to do at Fry’s. Or really any other store for that matter. Even then, assuming a perfectly quiet listening room with no echos, what would you listen for? Any decent speaker will spew out sounds that are beyond my range of hearing so there’s got to be more than that. I usually try to listen to the highs and the lows just to get an idea of the range of the speaker first. The clarity of the cymbals and the boom of a kick drum or bass are good reference points, but like with the Bose Wave radio, that can sometimes be misleading. I’ll then concentrate on the middle of the sound. Can I distinctly hear the vocal against the guitar or do they kind of blend together? Does it sound like the speaker is at the end of a tunnel? If so, that’s a bad sign even though that’s pretty much what I hear when I listen to those little cube surround speakers that usually come in “home theater in a box” sets. The problem is that speaker makers price their speakers, for the most part, according to how good they sound. Which, I guess, is what they’re supposed to do.