In digital audio, the sample rate in kHz determines the Nyquist frequency (highest capturable frequency) = sample rate ÷ 2. CD-quality 44.1 kHz captures up to 22.05 kHz — above the range of human hearing (typically 20 Hz–20 kHz). 48 kHz is the video/broadcast standard. 96 kHz and 192 kHz are used for high-resolution audio.
The human ear's frequency range is typically 20 Hz–20 kHz, declining with age. Most adults over 25 cannot hear above 16–17 kHz. The primary benefit of high sample rates is not capturing ultrasonic frequencies (which we cannot hear) but allowing gentler anti-aliasing filters with less phase distortion in the audible range.