Minor second dissonances

[Mr Showbiz]

Why do some minor second intervals sound more dissonant than others to me?

Also why does this dissonance seem to be affected by the register played; worse in the middle registers? (This would appear to counter the overtone series.)

Is it my imagination?

[sonics]

What's the instrument under discussion? If we take a perfectly intonated instrument tuned in equal temperament, all the intervals should sound the same. Other instruments may be very different indeed. Also, beat frequencies occurring with change depending on the pitches played.

Perhaps tell us more about where you are noticing this effect?

[Martin Walker]

I suspect it all depends on how long this interval is held, and if it then resolves to a more 'natural' sounding cadence.

[adamburgess]

Do you mean only minor 2nds on their own? Like E+F sounds 'different' to A+Bb?
Probably won't be too dissimilar in themselves, but all about context. What's before and after etc…

Paired with another note(s), there's lots of interesting chords to be had.
They can end up as suspensions, or be 'softened', or made more 'dissonant'…

[merlyn]

Dissonance and beat frequencies are pretty much the same thing. Consonant intervals don't beat as much as dissonant intervals. There is beating between the fundamentals, and also between the harmonics. Take the most consonant interval : the octave.

Code: Select all

A3 : 0220 0440 0660 0880 1760 ...
A4 :      0440 0880 1320 1760 ...

There's nothing to beat there. If the two notes were out of tune we would hear beats. The second harmonic of A3 is exactly the same frequency as the fundamental of A4.

Now take a semitone (rounding to the nearest Hz):

Code: Select all

A4 : 0440 0880 1320 1760 2200 ...
Bb4: 0460 0920 1380 1840 2300 ...

There are beat frequencies of 20Hz, 40Hz, 60Hz, 80Hz, 100Hz ... which is what we hear as dissonance.

Semitones do sound different depending on what pitch they are at. All intervals sound different depending on what pitch they are at because pitch is logarithmic and beats are a simple arithmetic difference in frequency.

[Arpangel]

B Minor is the worst, or the best, depending on how you look at it.
I composed a piece in B Minor, and it always sounds a bit weird compared to other keys, and, it has a series of left hand chords in it that comprise mainly seconds, or ninths, which sound very odd. The seconds, or ninths, definitely sound slightly dissonant compared with other keys.
Yes, some keys are different in this respect, maybe this is a side effect of equal temperament, compared with other methods of tuning.

[sonics]

Yes, some keys are different in this respect, maybe this is a side effect of equal temperament, compared with other methods of tuning.

Surely that "side effect" would be all keys sounding the same?!

[shufflebeat]

...all about context. What's before and after etc…

Also what's around it - it's a thin line between a minor 2nd and a major 7th.

[shufflebeat]

Yes, some keys are different in this respect, maybe this is a side effect of equal temperament, compared with other methods of tuning.

Surely that "side effect" would be all keys sounding the same?!

BBC "Key Matters":

https://www.bbc.co.uk/programmes/b00tw55v

Conclusion (if memory serves) - probably all the same unless you've been conditioned into a particular way of thinking.

[Martin Walker]

BBC "Key Matters":

https://www.bbc.co.uk/programmes/b00tw55v

Conclusion (if memory serves) - probably all the same unless you've been conditioned into a particular way of thinking.

Ooh, great link - thanks shufflebeat!

[shufflebeat]

I can't remember if I caught every episode but I will try to check it out again.

[merlyn]

B Minor is the worst, or the best, depending on how you look at it.

Depends who you ask. According to Spinal Tap, D minor is the "saddest of all keys".