About Audio Filter

Play your ipod library or hook your microphone up to pass through various types of digital audio filters before going to speaker or headphones. This also demonstrates designing digital audio filters by touch. Select from a variety of filters and set cut-off frequency and rolloff or stopband level. You can use this app to reduce various interferences or noise in the audio to improve your listening experience For processing the microphone, you'll need headphones or headset to avoid feedback noise

Current free version allows design of Butterworth, Chebyshev, Remez, and Maxflat subband filter types for both low-pass and high-pass filtering in addition to a simple notch filters such as 50 Hertz Notch. In App purchase allows upgrade to use more filter types as well as enabling high-pass filters. In addition background processing of audio is enabled.

How to Use

Use Horizontal Swipe in region above -10 dB to change passband. Below this will change stopband region if appropriate.

Use Vertical swipe to change passband ripple, stop band level and/or filter order.

Use Double Tap or Pinch to Zoom.

Single Tap resets view if zoomed otherwise it brings up Audio Panel.

Select Microphone Sample Rate in Settings if change from default is needed.

Use Audio Panel to select from either Microphone input or iPod library

Examples

Filter Selection

Remez FIR

Notch filter

Cascaded Integrator Comb filter (CIC)

Comb filters

Cut/Boost filter

Maxflat FIR

Maxflat subband filter

50 Hz notch filter

Butterworth

Chebyshev

Elliptic

Gaussian filter

Low/High Pass shelve filter