What is the range of frequency response of earphone

Frequency response range is refers to the headset to be able to send out the band width, excellent headphones frequency response width can be up to 5 hz - 40000 hz, and the scope of the auditory in only 20 hz - 20000 hz. It is worth noting that the defining standard of the width of the frequency response is different, for example, on the basis of lower than the average output amplitude 1/2 or less than a quarter as the standard, this is clearly not the same. Generally the manufacturer of the output amplitude lower 1/2 measured frequency response on width, that is on the basis of 3 db, but due to the test standard adopted by the different, some products are - 10 db for the standard of measurement. This is in fact is equal to 1/16 below normal for the standard measure.