like for example digital unit measurement for clear images in devices is ....pixel
The analogous unit of information for audio would be a "sampling" or "sample". That's the smallest unit of sound information in an audio stream and represents an approximation of the pitch and volume attributes of a sound at a moment in time. The sampling rate called "CD quality" today is sampled at 44,100 times per second for two (stereo) channels.
I think the answer you probably wanted was: Total Harmonic Distortion, which is a measure of how linear an audio device is. In the digital audio age, there will be an intervening Analog-to-Digital, and Digital-to-Analog conversion process, but the measure of linearity / clarity is essentially the same as it was in the era of analog sound.
Strictly speaking, this is an audio engineering question, not one of physics.
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