Practical digital audio signal processing
Digital and analog. We often think of them, mistakenly, as equivalent things in different domains. But that’s a misunderstanding, and we often use the terms incorrectly. For instance, run a mic through a preamp and get a signal, we know Continue reading
We’ve seen that samples can represent a signal with greater peak amplitude than the peak sample values. If those sample values were higher, the output would exceed “1.0”, or 0 dB full-scale—I ll refer to these as “overs”. This brings two Continue reading
Let’s say we want to test the output of a DAC while it passes a pure sine wave. The “pure sine wave” requirement is a bit more difficult than it might seem. In the general case, it’s not possible to Continue reading
A listening test in video form. On the plus side, it s helpful to see the spectrum as it s playing, and a peak meter to see how the sweeps compare to each other, and to the announcing voice. On the minus Continue reading
Click to play in your browser, or right-click-download to play as you wish (24-bit .wav file): multi-level sweeps.wav I call this a listening test, because it involves your ears, equipment, and even environment. Any of these can influence your limits Continue reading
The latest version of the biquad calculator. It also takes on the functionality of the frequency response grapher:
I ve been involved in several discussions on timing resolution in digital audio, recently—honestly, I never knew it was a concern before. For example, in a video on MQA, the host explained that standard audio sample rates (44.1 and 48 kHz) Continue reading
This video demonstrates important uses of AM—and serves as a demonstration of using the AM widget.
Here s Amplitude Modulation Deep and Fast, a not too lengthy video that gets to the roots of what amplitude modulation does mathematically. I’ve referred to AM’s role in sampling theory in past articles, and its relatively simple math makes understanding Continue reading
Frequency Hz Amplitude % 1 A 2 3 1 B 2 3 Experiment with amplitude modulation with the AM widget. Here s a diagram of how it works; two sets of three summed sinusoids to simulate two signals, the two are multiplied together for amplitude modulation: Tremolo: First, simulate a musical signal with three harmonics by setting A1 to 100 Hz at 60%, A2 to 200 Hz at 50%, A3 to 300 Hz at 40%. With all B…