In a word, no. First, it isn't just a matter of "picking up" frequencies. There is noise, transient response, overload and harmonics, etc... You might be abl

In a word, no. First, it isn't just a matter of "picking up" frequencies. There is noise, transient response, overload and harmonics, etc... You might be able to mimic some of that with signal processing, but microphones are also designed with different directional responses for different situations. That has a big impact on the eventual signal that is recorded and will not be recreated with a built-in cell phone mic.