Spectral
A Triangle-person is pictured standing on a meadow. There are some cumulus and cumulonimbus clouds in the background, and a bumblebee and a dragonfly are hovering around. The title says: “I used to think sight is superior to hearing”
The same Triangle-person is shown staring at a colourful meadow. Lines of sight are delineated with dashed lines, and a lot of the meadow is visible simultaneously. Title: “There is some truth to it. We see a lot of detail - the resolution is spatially incredible!”
Next, the person is staring at three flowers - red, green and blue. There is a matching-colour wave coming from each flower, hitting Triangle’s eyes. Title: “But spectrally it’s poor - we really only ever see 3 colours.”
Then, the person is listening to the sounds - a bird, a dragonfly and a bumblebee are being noisy. “Sound has a very poor spatial resolution. We either hear a sound, or we don’t”
On the final image, the person has eyes closed. There are 6 distinct waves coming at them, each at different frequency. They come from the thunderstorm, airplane, grass, bumblebee, dragonfly and the bird. “Instead it is spectrally insane! Even untrained ear can discern thousands of pitches!”
“So hearing is the opposite of vision - but just as powerful!”
“Spatial” means where things are positioned. Our eyes have millions of receptors, so we are able to perceive an Ultra-HD space in an instant. Ears are much more limited in space: we only have two of them, left and right.
“Spectral” means covering different frequencies (pitches, colours). Lower pitch has lower frequency, higher has higher, with large variety in between that our ears can perceive. For vision this is much more limited - we only have red (low frequency), green (medium frequency) and blue (high frequency).
There is some nuance to the claims I’m making. One counterpoint is that we seem to be able to perceive millions of colours, not just three. However, this is our brain playing tricks and interpreting the basic three-frequency mix (red+green+blue, RGB) as a unique mixture. But this colour information can still be reduced to just RGB. For example the screen you are looking at has only three LED types (RGB), yet it appears way more rich.
The other counterpoint is that hearing seems very spatial - we can hear sounds coming from different directions! Not quite - this is again our brain interpreting the 2-point (stereo) signal by using tricks like delay or sound shadow of our head, giving us an illusion of directionality. The information can still be reduced to just stereo sound. For example games can easily produce an illusion of directional sound with just headphones.
Here are some valid omissions though:
- in our eyes we have a grayscale receptor for night vision, which registers intensity of light, but not colour. This is a fourth signal in our sight.
- Some people carry a genetic mutation that gives them 4 colour receptors. It’s not established whether this confers any additional ability over the usual three.
- when we are trying to pinpoint the source of sound, we naturally turn our head. This helps us discern up from down, and left from right, so arguably goes beyond a simple 2-point reception, albeit separated out in time.