Grandma Moon Speaks: Bit Depth and Sample Rate of the Human Ear

Topics Covered:

  • The Bit Depth of the Human Ear
  • The Sample Rate of the Human Ear

I don’t make music for eyes. I make music for ears – Adele

CD
Created by Arun Kulshreshtha. This vector graphics image was created with Adobe Illustrator.

From Loudness or Volume we know that the sensitivity of the human ear is about 130dB. This call also be called the Dynamic Range of the human ear.

The formula to convert Dynamic Range to bit depth is as follows:

DRdB = 20 x log10(2n) = 6.02n

For DRdB = 130dB, n = 22.

When n = 24, DRdB = 145 dB
When n = 16, DRdB = 96 dB

Audio CDs are encoded at 16 bits, while DVD Audio is encoded at 24 bits. In theory, it seems as if an audio bit depth of 22 is the minimum to cover the human ear.

In reality, an audio analog to digital converter (ADC) is only capable of about 130dB, even if a theoretical maximum of 144dB is achievable with 24-bit audio. In practice, this level of quality is more than sufficient for the average human ear.

Why? One of the reasons is that even across the full frequency spectrum (20 Hz to 20 KHz), the human ear is most sensitive between 2 KHz and 5 KHz. Just because we have a theoretical limit of 130dB doesn’t mean we can process or perceive all that at the same time.

For our purposes, though, we can state with authority that an audio bit depth of 24 will cover the human ear adequately, while still leaving enough room for overhead.

Takeaways:

  • The Audio Bit Depth of the human ear is 24
  • The minimum Sampling Rate of the Human Ear is 44.1 KHz

Links for further study:

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