The amplitude of the analog signal produced with a sampling frequency of 44.1 kHz will be measured at a rate of 44100 times per second. This sampling frequency will accurately represent anything within the spectrum of what humans are able to perceive (ranging from 20 Hz to 20 kHz). This is also the sampling frequency used in audio CD's, and is the standard.
The higher the sampling frequency, the greater the frequency content of the source material that can be accurately represented in the recording. Audio sampled at a rate of 22.05 kHz will contains half the number of "samples" of audio sampled at 44.1 kHz (with an upper range of 10 rather than 20 kHz). However, higher sampling frequencies require more file storage space. A sampling frequency of 44.1 kHz may not be necessary for the recording of spoken human voice, as most of the range of the human voice occurs below 10 kHz. A digital audio file produced at 44.1 kHz will be twice the size of a file produced with a sampling rate of 22.05 kHz, however, the quality of the audio of human narration will not double.