Hear No Evil, Feel No Evil by Matthew Slater

Sound is weird. In its simplest state, we could say that sound is built by vibrations which when transferred by a medium, like air, are then interpreted by our ears and can be audibly perceived. However, humans have a limited frequency range on what they can and cannot hear and because of this, there is a grey area where it is uncertain if humans can actually perceive these sounds that are audibly out of reach as it were. The argument is that sound can be felt by the human body. We can sense particular sounds, although we may be unaware of it. These sensations are what I want to talk about.

For instance, you can tell if a muted TV set is on by somehow sensing it – like the static beams out of the screen towards you or something. The same can be said for particularly low sounds, where experts reckon that our senses that perceive these sounds are leftover from our hunter-gatherer days, when earthquakes and loud predators that might create a rumble were both dangers to our lives. Ideas like these are harnessed in the audio world, particularly in films, where these subtle suggestions work their magic on the audience.

The Nyquist Thereom dictates that audio needs no greater range than upwards of 20kHz and below 20Hz. It states that bit depth or resolution can increase the dynamic range of sound, but that sampling rate will make no difference whatsoever due to the threshold of human hearing. However, technology in the past was also limited in what it could achieve, but the digital revolution has made it easier than ever to be able to produce and pump up the volume of these inaudible frequencies in order to try and make them more prominent.

Sampling rates can be increased in order to give the frequencies above 20kHz a boost, and to give the music a greater amount of headroom with regards to pitch. CDs use 44.1kHz as its sampling rate, meaning that the audio detail drops off at 20kHz or so. This means that the next consumer audio format to raise this threshold will allow the masses to feel these sensations, or at the very least have more detail present in their music. A win-win by all accounts.

The argument of whether we feel or perceive these frequencies at all can be debated, but the technology behind harnessing them is the same technology that will give us greater listening pleasure in the future. The jury is still out.