The modern PC sound card contains several hardware systems relating to the production and capture of audio.
The digital audio section of a sound card consists of a matched pair of 16-bit digital-to-analogue (DAC) and analogue-to-digital (ADC) converters and a programmable sample rate generator. The computer reads the sample data to or from the converters. The sample rate generator clocks the converters and is controlled by the PC. While it can be any frequency above 5kHz, it’s usually a fraction of 44.1kHz.
Read page 63 of the textbook “Exploring Computer Hardware”.