A speaker will try to reproduce any frequency that is presented to it, they are more efficient in certain ranges. Speaker ratings are basically talking about these ranges. A speaker, by itself can't be selective, that is a crossover's job, selecting the proper frequency for a certain speaker..... (yes there are some higher end speakers with built in crossovers but a raw speaker can't do this on it's own) As in the old style Woofer/Mid/Tweeter cabinet there was a predetermined crossover made of capacitors and coils/resistors to channel the proper frequency range to each driver. In a modern multi speaker computer "set" as in a 2.1 or 5.1 multi media kit the crossover is usually active and built into the amp. Lower cost kits may rely on the sound cards various outputs for this.