Sample Rate

Sample rate is the number of times per second that an audio signal is measured (sampled) when converting from analog sound to digital data. It is measured in hertz (Hz) and determines the frequency range that the digital audio can accurately reproduce.

The standard sample rate for audiobooks is 44,100 Hz (44.1 kHz), which is the same rate used for audio CDs. This sample rate can accurately reproduce frequencies up to about 22,050 Hz (half the sample rate, per the Nyquist theorem), which covers the entire range of human hearing (approximately 20 Hz to 20,000 Hz).

Some audiobook production workflows use higher sample rates like 48,000 Hz (48 kHz) during recording and editing, then downsample to 44.1 kHz for the final distribution files. Higher sample rates during production provide slightly more headroom for audio processing and effects, though the difference is inaudible in the final product.

For AI audiobook production, the sample rate is determined by the TTS engine used. Most neural TTS services output audio at either 22,050 Hz or 44,100 Hz. When the output is at 22,050 Hz, it may need to be upsampled to 44,100 Hz to meet distribution platform requirements. Quality AI audiobook tools handle this conversion automatically.