Aliasing

Aliasing refers to the distortion or artifacts that occur when a signal is sampled at too low a rate or improperly filtered. When a continuous analog signal is converted to a digital signal, it is sampled at a specific rate, known as the sampling rate, which determines the maximum frequency that can be accurately represented in the digital signal.

If the sampling rate is too low, frequencies above the Nyquist frequency (half the sampling rate) can fold back and appear in the sampled signal at lower frequencies, causing aliasing. This can result in unwanted sounds, such as high-pitched whines, distortion, or in extreme cases, complete loss of the original signal.

To avoid aliasing, it is important to use a high enough sampling rate and to properly filter the signal before sampling to remove any unwanted frequencies above the Nyquist frequency. In digital audio, this is typically done using an anti-aliasing filter, which removes any frequencies above the Nyquist frequency before the signal is sampled.

Aliasing can also occur in the playback of digital audio if the sample rate of the digital audio does not match the playback device's sample rate. This can result in a loss of quality and unwanted artifacts in the audio playback.

Dither is a process used in digital audio to minimize quantization errors that occur when converting analog signals to digital signals. When a continuous analog signal is converted to a digital signal, it is sampled at discrete intervals, which results in a loss of information and a rounding error known as quantization noise.