Do we care about “high-def” audio?
August 6, 2008 by Christopher Swenson
Filed under Electronics
A lot of newer audio technologies have been promising “HD” audio, with features such as “192 kHz sampling”. But what does this mean?
CDs sample 44.1-kHz audio at 16 bits per sample. Considering the standard was defined back in the early 1980s to be played with state-of-the-art technology back then, you’d think this is far inferior to what we could cough up now, right?
Not really. For starters, 44.1 kHz allows the audio to accurately represent any waveforms below about 22 kHz (due to the Nyquist-Shannon theorem). Well, human hearing only extends to about 20 kHz, and less so as you get older. Basically, 44.1 kHz is plenty for high-def audio. DVDs standardized their audio sampling rates at 48 kHz, probably so they have nicer, rounder numbers to work with.
So, do these mega-high-fi 192 kHz do you any good? Nope. Not really at all. Due to the logarithmic nature of human hearing, going that high really does very little for your listening experience.
Don’t believe me? Well, see how well you can hear by trying out the so-called mosquito ringtones. These ringtones are made for teens so that adults can’t hear their phone ring.
So, what about 16-bit? Surely 16-bit means terrible, right? Well, not really. I mean, how bad do your CDs really sound? Granted that 16 bits are quite enough to represent the gamut of sounds that humans can differentiate (16 bits give you about 65,536 levels of sound to play with). Newer systems support 24- and 32-bit audio samples, which should definitely top out humans ability to hear on both ends.
But really, 16 bits are plenty for most people. For one thing, the quietest sound you can possibly hear is about 0.00002 Pascals and the loudest sound you probably ever want to hear (a jack hammer) is about 2.0 Pascals, giving you approximately 100,000 different sound levels between them. 65,536 levels can still put you to the point of hearing loss while allowing you to hear sounds an order of magnitude quieter than the softest whisper.
So, really, 16-bit, 44.1 kHz audio really is pretty decent. Anyone who tells you that you need 192 kHz 64-bit sampling is pulling your leg.
