I found some speaker which has reponse from 40-60.000 hz. Does that high frequency (60.000hz) do any good in sound? because human ear only hear max 20.000 hz?
Different schools of thought. There will be those that go by numbers and tell you that anything above is pointless and will make no difference whatsoever, then there will be those that talk about harmonics that are way above our hearing that will still have an effect on the frequencies we can hear.
Ignoring whether anyone can hear them; which sources are capable of presenting 20KHz - 60KHz musical signals to the amp and speakers?
If there is source equipment that can do this; are there any media for these sources (downloads, CDs, LPs, radio etc.) that can carry frequencies this high?
If the answer is 'no', then tweeters capable of 60KHz are just for technical 'bragging rights'.