What does bit depth refer to in digital audio?

Bit depth in digital audio specifically refers to the resolution of sound wave amplitude. It determines the number of discrete levels that the audio signal can be represented with, effectively influencing the dynamic range and overall audio quality. A greater bit depth enables the capture of more detailed amplitude variations within the audio signal, resulting in a more accurate and higher fidelity representation of the sound being recorded or played back. This is crucial for achieving a sound that reflects nuanced details and reduces distortion, particularly in quieter passages.

The option regarding the resolution of time relates to the sample rate, which defines how many times per second the audio signal is sampled. Data transfer rate pertains to the amount of data transmitted over a network, which is not directly tied to the representation of audio amplitude. Lastly, the number of channels available refers to the way audio is routed, such as stereo or surround sound setups, and does not impact the depth of each individual audio sample.