Speaker specifications are often ignored for the main reason is that they sound complicated. This will help to understand
speaker specifications and to maybe answer some questions you may have about them.

Reading Specifications

Power Rating (Watts) - Power rating is givin on every speaker system(eg. 200 Watts) Power ratings are the #1 rating used to help make a speaker look better. Some people choose a speaker because of the big number on the power rating. Never purchase a speaker because it has a higher power rating than another. Power ratings are actually almost useless to the average person. What a power rating really means is how much power you can deliver to a speaker without causing physical damage to the unit -- this rarely every happens if you have a powerful enough amplifier. There are also many different types of power ratings out there. If a speaker says it is rated at 200 watts, that does not mean it can nessecarily play louder than a speaker rated at 100 watts. It also does not mean that it will play clean undistorted sound when fed 200 watts or even 100 watts! Some companies also only provide you with the maximum power handling rating. This is completely useless. It simply tells you how much power the speaker can handle for a very short period of time without burning out the voice coils. The power rating that actually means something is the RMS or continuous or nominal power handling reading. This indicates how much power you can feed to a speaker continually without any damage. So don't purchase a speaker or think one is better because it gives a higher power rating.

Frequency Response (Hz) - You will find this specification on almost every set of speakers. It is probably the #2 reading not to beleive on most speaker system ratings. It basically tells you the range of frequencies the speaker is able to produce. (eg. Frequency Response: 20Hz - 20kHz). This indicates that the speaker is able to produce sound frequencies between 20Hz(deep bass) to 20kHz(high treble). This is completely useless unless it gives a range of loudness where the speaker can produce these frequencies. If the speaker says: (20Hz - 20kHz) - it will play everything in that range, its just that 20Hz - maybe even 40Hz will be so quiet, you may not be able to hear it! Many 'mid class' manufacturers (Sony, Pioneer, Kenwood, RCA, JVC etc.) will give you a frequency response rating -- but that is not achievable in your own listening environment. If the response says: (40Hz - 20kHz +/- 3dB) it says a lot more more. This means that the loudness will remain approxamately within 3dB of loudness from 40Hz to 20kHz. These ratings can be measured many different ways to try and improve the frequency response of a speaker so unless you are buying from a reputable audio dealer or buying a pair of high quality speakers, don't pick by the frequency response indications and don't trust them. Trust your ears! If you really want to know what the frequency response is, you need 2 items. Get a cheap sound test CD or a more costly sound frequency generater, and a SPL meter from Radio Shack. Play the track(s) with the frequency sweeps and use the SPL meter to determine how loud each frequency is. The lower limit of a speaker is usually measured at the -3 dB point.

Sensitivity (dB) - Is givin on most speakers. (eg. 90dB Sensitivity). It indicates how well a speaker converts electrical power into acoustic energy. The more sensitive the speaker, the better it converts electrical input into sound. This causes less heat buildup and the speaker is more reliable. This does not mean the speaker sounds better. 90dB sensitivity means that when you set an amplifier to put out a signal of 2.83V (1 watt) and you measure the SPL at a distance of 1 meter away, the speaker will produce 90dB Sound Pressure Level at usually 1kHz. This also means that given the same input, a speaker with a sensitivity of 93dB will need half as much power to produce the same loudness on a pair of 90dB speakers! Again, sensitivity has nothing to do with how good the speaker is overall.

Impedance / Resistance - measured in ohms - Is also givin on many speaker systems. (eg. 8 ohms). Ohms can also be represented by a horse-shoe symbal. It indicates the amount of electical resistance a speaker makes on an AC current from an amplifier. Because impedance changes throughout the freqeuncy range, a nominal reading is usually recorded. Speaker impedance is usally 4, 6 or 8 ohms. This is an important measurement when matching a set of speakers to an amplifier. Amplifers will give a minimum resistance reading like 8 ohms. That means that you should not hook up a speaker with a less than 8 ohm impedance rating unless you are skilled in electronics. More expensive amps usually are capable of 4 ohm loads. This is because the lower the resistence to the amplifiers current, the more current the amplifier will put out, and if the current level is too high, it will burn out the output transistors (or tubes if you have a tube amplifier). As I said before, the impedance changes throughout the freqency range from a high of about 30 ohms at resonance, and 6 ohms in the upper bass region but it changes from speaker to speaker.