# A filter in IOS to eliminate a certain frequency range

I am making an application where I record sound on an IOS device using the built-in microphone. I want to process the sound in such a way that only frequencies in the 16-18 kHz range remain; the other frequencies should be eliminated. I read in some posting that I can use a band pass filter to get this result. Any help will be appreciated.

See this page for detailed descriptions (including source code) of scientific python commands that do what you need. Look in particular for convolve and firwin2.