This applet is a demonstration of digital filters. Click the "Sound On" checkbox to turn the sound on.

The applet starts up with a low-pass filter. It shows the frequency response of the filter, the spectrum of the filtered waveform being played, the waveform itself, and the impulse response of the filter. Click on the response curve to change the cutoff frequency.

You can use the popup menus on the right to select another filter or input file.

Full Directions.

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Full screen version.

Original Java version.