Category Archives: Impulse Response

Convolution—in words

Convolution is a convoluted topic—and that’s what it means (convoluted, from Merriam-Webster : “Extremely complex and difficult to follow. Intricately folded, twisted, or coiled.”). Really, it’s more difficult to explain why you would want to use convolution than it is … Continue reading

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A closer look at upsampling filters

Interpolation type:NoneZero-order holdLinearSinc 1Sinc 2Sinc 3  Show impulse response Sweep! In this demonstration, we generate a sine wave sweep from low in the audio band to near the Nyquist Frequency, which is half the sample rate. You can view it … Continue reading

Posted in Aliasing, Digital Audio, Filters, FIR Filters, Impulse Response, Sample Rate Conversion, Widgets | Leave a comment

Building a windowed sinc filter

As promised, here’s our windowed sinc calculator for building a 2x oversampling filter:  Factor  Length  Rejection  Gain Notes: Use the Tab or Enter keys to effect changes (most browsers), or press Calculate. The frequency axis is in multiples of the … Continue reading

Posted in Digital Audio, Filters, FIR Filters, Impulse Response, Sample Rate Conversion, Widgets | 2 Comments

Towards practical resampling

In a previous article, we looked at sample rate conversion in the frequency domain. Let’s take a quick second look in the time domain as reinforcement of principles behind sample rate conversion, before developing a practical rate convertor. In an … Continue reading

Posted in Digital Audio, Filters, FIR Filters, Impulse Response, Sample Rate Conversion | 6 Comments

A bit about reverb

Reverb is one of the most interesting aspects of digital signal processing effects for audio. It is a form of processing that is well-suited to digital processing, while being completely impractical with analog electronics. Because of this, digital signal processing … Continue reading

Posted in Convolution, Digital Audio, Impulse Response, Reverb | 7 Comments