Why is singing/playing an instrument off-key a thing? Why are some frequencies of the acoustic wave okay and some not okay?
In: 13
This is really about temperament. Modern society favors a 12 tone temperament. That means that frequencies are divided into 12 steps before repeating at another octave. That is for every doubling of pitch/frequency, we divide into 12 even steps. There is some music that uses different temperaments, but I think it’s safe to assume we are talking about typical music.
That means anything outside of those 12 steps sounds unpleasing to us. The why for that would go well beyond ELI5 though. I consider music to be sort of an exploitation of the way humans communicate emotion. Pitch, Timbre, and tempo determine the emotion being conveyed. For example someone in a panic will speak at a very high pitch, high timbre, and with a fast tempo. Where as someone expressing sadness will speak in a more slow tempo with a lower pitch. Someone expressing sadness would do so in a minor key, while someone happy will use a major key. These are increments of those 12 steps. Different combinations produce different emotions. Changing a song from a major key to a minor key can change it from happy to sad.
So somewhere through time we developed these quantized frequencies to properly communicate emotions to each other. Going outside of these steps is kind of like speaking another language emotionally and we respond with displeasure. It goes against the way we evolved to communicate. It’s not really easy to give a simple answer because it could have easily been a different temperament. We would have evolved to use a 19 tone temperament and think that 12 tones sounds bad to us. It just happened that we have 12 tones. It had to be something. And another factor would be the symmetries of the notes. Each one having a wavelength. A note an octave up is going to double the frequency and you can fit two waves evenly into the lower octave. If you don’t stay within these steps that add up evenly, then the waveforms will beat against each other which tends to sound unpleasant to us. So the mathematics of it is probably how we evolved to where we are now. How waveforms sum also dictates the emotions communicated. A major scale may sound happy, a minor scale sad, a Phrygian scale may sound more mysterious. But once you go outside of this structure, meaning tuning that is between these 12 steps, you get dissonance and the emotional communication breaks.
Latest Answers