5 ms·
Look at it from a frequency perspective instead of genetic. When you overlay two waveforms that are related x:1, the zero points of the waveforms align. The wa
by joshka 4y ago
Look at it from a frequency perspective instead of genetic.
When you overlay two waveforms that are related x:1, the zero points of the waveforms align. The wave resets at the same instant. If instead the waveforms are related not exactly, then you get a change in where the reset point is that drifts and causes the wave to exhibit beating (changes in volume).
If you have a 2:1 (octave) relationship between 2 waveforms, then you won't hear the beating as the beat frequency exactly overlaps the frequency of the lower frequency.
If you have say two notes that are not quite in the octave ratio, then you hear beating at the difference in frequency. E.g. say 440Hz and 888Hz (instead of 880Hz), you have beating occurring at 448Hz, which you'll hear as an 8Hz (448Hz-440Hz) wobble in the sound volume of the combined wave.
- jacquesm 4y agoThere are some assumptions about phase in there.
- joshka 4y agoYeah, you're right.
- ordu 4y ago> If you have a 2:1 (octave) relationship between 2 waveforms, then you won't hear the beating as the beat frequency exactly overlaps the frequency of the lower frequency. If we take a look into a human ear we'll see there an apparatus which physically splits sound into a spectrum of frequencies (a long narrowing tube, sound comes from one end and it creates resonances at different places) and a lot of receptors which placed in such a way that allows them to specialize on different frequencies. I know nothing that would point to an innate ability of this apparatus to feel octave as something special compared with a mix of two random frequencies. So the peculiarity we hear pops up on later stages of sound processing. But why it pops up? Moreover there is an evidence (I have no link, sorry) that the peculiarity of an octave is a cultural thing, not a genetic one. European music teaches us to feel octave as something special. There are tribes not exposed to European music who doesn't feel consonance and dissonance like we do. My hypothesis that a mind picks correlation between a frequency and a double frequency. I mean it is not because of some funny math comparing two sine waves, it is because sounds essentially are not single sines. Two sounds forming an octave are both sums of many sine waves, and there is a huge overlap between sets of frequencies, so they sound similar. And then, when mind trains on this data, it becomes conditioned on a similarity of double frequencies, so it starts think of two sines with frequency ratio of 2:1 as of similar. The similarity is just a correlation. And people who didn't tried to make a music with strings cannot grasp the idea, because natural sounds mostly much more complex than just sum of a several sines with frequencies that are multiples of some base frequency.
- hoseja 4y agoWhat? No, you said it, the ear splits the sound into frequencies and physically puts sensors into places where they resonate. Octave resonates in the same place. (but higher octave resonates in one additional place)
- ordu 4y agoNo, octave resonates in two different places. If we talk about octave as of sum of two sines.
- hoseja 4y agoI was sloppy. First i meant the octave as two separate tones (one after another), then I meant only the higher pitched one. The higher tone also excites the sensors for the lower tone. Wait, does it? I might be spouting bullshit, sorry.
- ordu 4y ago> Wait, does it? Thinking about it, I'm not so sure it doesn't. I'm not a physicist to know it for sure.
- crubier 4y agoIt depends on what type of oscillator we are talking about, but strings, chambers or beam oscillators for example will resonate at double frequency of their main frequency. The octave rule definitely has some physical/biological founding, it’s not purely cultural. Although culture also plays a role in its preponderance.
- hwc 4y agoEvery note is a sum of harmonic sine waves, usually not just a single one. The first harmonic of 440hz is 880Hz. So plucking a harp string for A4 will also produce the A5 and A6...