Two samples are needed. Remember the Nyquist freq is 1/2 the sampling rate.
These two samples make a square wave at the Nyquist and after filtering make a sine wave. All a human can hear at 20Khz is a sine wave (even tho the waveform may have higher harmonics) . The higher harmonics that make the square wave are NOT audible. And yes mathematically all that is needed is two samples at 44.1Khz. The key here is that a complex waveform with higher harmonics above the Nyquist is NOT accurately reproduced but the waveform's harmonics up to the Nyquist ARE reproduced. The freqs below the Nyquist is ALL that we care about.
Typically the sample rate is a little more than 2x the highest freq to be reproduced since the ADC and DAC filters are not perfect.
Michael