arduino drum SD card DIY (PROBLEM)

yes, if the sensor is hit alternately all sounds good.
but once hit together with 2 or more sensors then the problem arises because one of the sounds will be lost.
should be one two three four or all beaten should the sound will all hearing together.

certainly this is not like the real drum is not ...,

so what you advise,please give me link or some thing for me to learn.