Downsampling issues

1. What is the effect of downsampling?
2. What is meant by downsampling?
3. Does downsampling affect quality?
4. How does downsampling affect the spectrum?

What is the effect of downsampling?

Performers might sometimes downsample a signal as an effect, to achieve a low-fi sound. The anti-aliasing filtering will reduce the bandwidth of the signal and attenuate the high frequencies, and the interpolation process, depending on how it is done, can add noise or "grittienss" to the sound.

What is meant by downsampling?

Downsampling (in this context) means training on a disproportionately low subset of the majority class examples. Upweighting means adding an example weight to the downsampled class equal to the factor by which you downsampled.

Does downsampling affect quality?

Yes, but don't worry about it too much. Some of the best sounding drums ever come out of 12 bit samplers, perfection is not necessary IMO. My sampler samples at 20,500 hz yet still sounds good. By definition it's a reduction of quality.

How does downsampling affect the spectrum?

The spectrum of the downsampled signal is a stretched and scaled version of the original spectrum, but the shape is preserved because the spectral copies do not overlap. There is no aliasing.