How to choose a speaker?

As a matter of fact, speaker is a by the audible range of audio power signal transducer (speaker unit) and transform it to have enough sound pressure level of audible sound. In order to choose a good speaker, you must first understand the properties of the sound signal, and then ask the speaker to "authentic" to restore the audio signal into a natural sound.
Music is a voice and a variety of random signal, the waveform is very complex. Audible frequency range up to 20HZ-20KHZ; the language of spectrum range approximately in about 150HZ-4KHZ; and all music spectral range up to 40HZ-18KHZ left and right. The energy distribution of the average spectrum is: the bass and the middle and low part of the biggest, the middle and high part of the second, the high notes of the smallest (about 10/1), the voice of the energy is mainly concentrated in the 200HZ-35KHZ frequency range. The audible signal amplitude peak random than its average value was 10-15DB (or even a little higher). Therefore, the speaker should be able to correctly re release these random signals, to ensure that the playback of the sound quality is graceful, the speaker must have a broad frequency response characteristics, enough sound pressure level and large signal dynamic range. We hope to use a relatively small signal power input to obtain a sufficiently large sound pressure level, that is, the speaker has a high efficiency of electric power conversion into sound sensitivity.
In addition, we also require that the speaker system in the input signal in the right amount of overload, will not be damaged, that is, to have a higher reliability. Another point is that users want to buy cheap and good product, that is, the higher performance of the product, but also to consider the product of the supporting way, the shape structure and lifting method and other conditions.