Car audio speaker merits?

In the purchase, to pay special attention to the performance of the car stereo speakers, to judge its merits, the most direct way is to look at its technical indicators. Mainly from the following aspects of the judge:

1, Harmonic distortion (THD): the index reflects the reduction of sound reproduction, numerical simulation shows the higher the degree of reduction, the better the quality of the effect.
2, The output power: now the host of the subject of the power of the vast majority of music power, in the 40W-60W between the power can not be too large.
3, Signal to noise ratio: it refers to the ratio of the music signal and noise, the average premium car audio speakers are more than 90DB, the bigger the better.
4, Frequency response: the human ear can hear the frequency range between 20HZ-20KHZ, so the index at least to reach this value, and the wider the better.