Frequency response
Also called frequency range · 20Hz to 20kHz
Frequency response is the range of pitches a speaker or headphone can reproduce and how evenly it plays them. Human hearing covers roughly 20Hz to 20kHz and small speakers lose the low end first.
The speaker test sweeps from 20Hz to 20kHz. Buzzing or rattling at one point in the sweep can mean a loose part rather than a failing driver.
In practice
Frequency response explains why laptop speakers sound thin and why headphones sound fuller. Small speakers can’t move enough air for deep bass. Very cheap ones also roll off the highest frequencies. A buzz or rattle at one particular pitch usually means something loose is vibrating rather than a failing driver.
How to check
Run the frequency sweep in the speaker test at a moderate volume and listen for where sound fades, buzzes or rattles. Note the frequency shown when it happens. Try the same sweep on headphones. If the problem disappears on headphones, it is in the speakers rather than the computer.