frequency-response

Frequency response is a measurement of digital [filter]s' effects on signals that they process. It measures the change in amplitude/loudness for each part of the frequency spectrum. Filters usually subtract from signals, taking some harmonics out while letting others pass through. However, filters can also attenuate/boost some parts of signals, which is what happens when you boost the q factor or use filter types such as lowshelf/highshelf/peaking filters.

Here's a plot from web synth's [filter-designer] [module] showing the aggregate frequency response of two composed biquad lowpass filters with different frequencies and q factors: