Musical questions and answers thread

[Alison]

Another question. Been meaning to ask this since January ....

FHG wrote

Musicians didn't come up with the Theory and then make the sounds apply to that Theory

Is that true of serialism ?

[EdgeleyRob]

May I just say this is a super thread.
Thanks Alison

[MrGongGong]

Harmonics for dummies anyone?

In my attempts at trying to learn how to read music I often come across mention of harmonics..



How do they work then? are they possible on all instruments?

Over to you music teachers.

When you say ALL instruments what do you mean ?

[EdgeleyRob]

When you say ALL instruments what do you mean ?

Please forgive my numptiness MrGG, I'm relatively new to this music theory and the like.
Re harmonics, I thought they were only possible on stringed instruments but presumably wind and brass too?

[MrGongGong]

Please forgive my numptiness MrGG, I'm relatively new to this music theory and the like.
Re harmonics, I thought they were only possible on stringed instruments but presumably wind and brass too?

The harmonic series applies to wind and brass instruments as well (that's how many instruments work)

[Richard Barrett]

FHG wrote

Musicians didn't come up with the Theory and then make the sounds apply to that Theory

Is that true of serialism ?

Yes, that is true of serialism (remember it's a method not a theory).

One example where it isn't really true is in the later work of Paul Hindemith, who even revised some of his earlier work to conform to the theory of tonality he explains in his Unterweisung im Tonsatz (translated as The Craft of Musical Composition), written in the mid-1930s, to their detriment IMO.

[Serial_Apologist]

Another question. Been meaning to ask this since January ....

FHG wrote

Musicians didn't come up with the Theory and then make the sounds apply to that Theory

Is that true of serialism ?

I think in the case of Schoenberg, the processes of elipsis and non-repetition undergone by his music before and during the so-called free-atonal period brought to his attention a fact that the tendency for rows to emerge spontaneously had been occurring in his music (and that of one or two others) for some time. Thus it became a small matter of organising the resulting note patterns in accordance with this emergent principle to create a unifying compositional principle. I don't know if Hauer reached his 12-tone method similarly; or for that matter Ives in his much earlier "Tone Roads I and II". Perhaps it's time we heard more about Hauer. Subsequent composers seem to have applied pitch serial practices without having gone through the, for Schoenberg and his pupils, "ineluctable" process of chromaticism and foreshortening of enharmonic sequencing deriving from post-Wagnerian practice "elbowing out" cadential resolution, and it is interesting to observe how this takes place consecutively in Dallapiccola's and Petrassi's works of the 1940s and '50s, they being among the first outside the Second Viennese School to take up the method, and Stravinsky's music from "canticum Sacrum" onwards..

[Richard Barrett]

Harmonics for dummies anyone?

In my attempts at trying to learn how to read music I often come across mention of harmonics. (...) How do they work then? are they possible on all instruments?

Over to you music teachers.

I'm not a music teacher as such, but: if you take the example you've illustrated, of the C string of the cello, the first harmonic, an octave above the open string, is produced by fingering the string lightly at the notated point - halfway along the string, doubling the frequency. The second harmonic is an octave and a fifth above the open string - fingered one third of the way along the string, tripling the frequency. (Another "node" producing the same resultant pitch is found two-thirds of the way along the string.) The third is two octaves above the open string, one quarter of the way along and quadrupling the frequency (with another node three-quarters of the way along), and so on. Once we get to the fifth harmonic, it can be played by fingering not only at the place (the low E flat) shown in your illustration but also in four other places, and so on. This works on all stringed instruments. In woodwinds and brass, playing different harmonics depends on making the air-column in the tube vibrate at analogous fractions of its overall length.

[Pabmusic]

Please forgive my numptiness MrGG, I'm relatively new to this music theory and the like.
Re harmonics, I thought they were only possible on stringed instruments but presumably wind and brass too?

Any sound (well, almost any) is a mixture of different harmonics generated by the original source in accordance with the laws of physics. With a bass drum, for instance, there are so many notes and their harmonics produced simultaneously by different parts of the drum that the ear can't sort them out. It's the same for a rap at the door, or a car engine. But with melodic instruments, it's different; the particular harmonics give them their 'colour' - it's why we hear an oboe rather than a clarinet, for instance. The beauty of instruments lies a lot in the way manufacturers and players can exploit the harmonics.

An intriguing thing is the way in which we hear sounds. We might assume that our brain notices the start of (say) an oboe note and continues to process that note for its duration. But that would require truly enormous processing power, so it notices only the start of the note and any subsequent change - caused perhaps by vibrato or pitch, or perhaps because the note ends. The brain does not 'hear' anything between these points, but simply constructs a virtual sound image from the last point. So we never actually experience the inbetween bits at all.

Now my brain hurts.

[Pabmusic]

Harmonics for dummies anyone?

In my attempts at trying to learn how to read music I often come across mention of harmonics..



How do they work then? are they possible on all instruments?

Over to you music teachers.

You ask 'how do they work?' Well, sound is a product of vibrations travelling in waves. But when the sound source is 'fixed' at each end interesting things occur due to interference. Take a string fixed at both ends (the easiest example by far since we don't have to wonder how a column of air can be 'fixed' - let alone how one 'fixed' point of a clarinet lies a few inches outside the instrument!). When you pluck a string you hear a note created by the vibration of the entire length of the string. It's a strong note too, since the energy is produced by the entire string. However, due to interference, the string also vibrates from each end to the middle (which doesn't vibrate - it's called a node). It also vibrates in thirds, in fourths and so on. Each vibration between nodal points produces a different note, depending on the distance between the 'fixed' or nodal points. These are the harmonics. They become fainter as their wavelengths decrease, since they are weaker.

When a string player lightly touches a string at a nodal point, the harmonic produced between that point and the fixed point sounds clearly (since other harmonics are dampened by the touch). The notes produced at each nodal point form the 'harmonic series'.

Similar things happen with columns of vibrating air (aka wind instruments). Some composers have exploited wind harmonics. Weber wrote a horn concertino (I think) that requires the soloist to produce chords by playing a note whist singing a different note and thus making certain harmonics sound. It's not very beautiful, though. Things can be done with percussion, too, and many composers have written 'ghost' chords for piano (hold down this without sounding anything while you play something else) to allow notes of the harmonic series to sound in sympathy. Berg, Grainger, Cowell certainly. Listen to W. Dennis Browne's great song To Gratiana Dancing and Singing for an example at the climax (he probably got it from Berg's piano sonata since he'd given the first performance).

Also, remember that all wind instruments are based upon the harmonic series (since that's what you can produce without any keys) to which has been added half a ton of plumbing to produce the missing notes.

Here's an article with some good information and a lot of maths:

http://www.phys.unsw.edu.au/jw/strings.html

[MrGongGong]

Any sound (well, almost any) is a mixture of different harmonics generated by the original source in accordance with the laws of physics. With a bass drum, for instance, there are so many notes and their harmonics produced simultaneously by different parts of the drum that the ear can't sort them out. It's the same for a rap at the door, or a car engine. But with melodic instruments, it's different; the particular harmonics give them their 'colour' - it's why we hear an oboe rather than a clarinet, for instance. The beauty of instruments lies a lot in the way manufacturers and players can exploit the harmonics.

An intriguing thing is the way in which we hear sounds. We might assume that our brain notices the start of (say) an oboe note and continues to process that note for its duration. But that would require truly enormous processing power, so it notices only the start of the note and any subsequent change - caused perhaps by vibrato or pitch, or perhaps because the note ends. The brain does not 'hear' anything between these points, but simply constructs a virtual sound image from the last point. So we never actually experience the inbetween bits at all.

Now my brain hurts.

Good stuff
Though i'm not 100% sure about the second paragraph. Whilst this IS true for "note based" musics (chop off the attacks and you can't hear the difference between many instrumental sounds playing the same pitch) outside the pitch based world where what you call "subsequent changes" are what the content of the music IS then the brain must process continuously.
I was also thinking about Alvin Lucier's pieces for solo instrument and sine wave generator where the music is created by the pitches beating against one another. In this music the "it's a C so I can stop thinking about that and concentrate on something else" , brain model wouldn't appear to work IMV.

I'm sure there's lots of stuff about this in electroacoustic theory , Smalley's Spectro Morphology would be a place to start I think.
Psychoacoustics is a very interesting area indeed.

[Pabmusic]

Good stuff
Though i'm not 100% sure about the second paragraph. Whilst this IS true for "note based" musics (chop off the attacks and you can't hear the difference between many instrumental sounds playing the same pitch) outside the pitch based world where what you call "subsequent changes" are what the content of the music IS then the brain must process continuously...

It's information theory, developed in the 1940s in respect of telephones, but seemingly true of brains too. It's generally more efficient than processing everything.

A similar thing happens with what we see. The brain can't process everything it senses without being many (many, many) times bigger. So it takes shortcuts. What seems like a flat expanse of colour is actually a response to the edge (the change) and many instructions to copy the new colour. The brain also makes assumptions based on what's happened before - presumably this is true also of sound, though I don't know.* This is what underlies much of why one person remembers things differently from another. It also explains many mistakes, since the brain makes wrong assumptions sometimes.

Fascinating stuff, particularly the fact that nothing we 'see' is actually real - it's all a virtual image constructed by our brain in response to stimuli from the eyes. I suspect there is an analogy there with hearing, but I'm not a neuroscientist.

*[According to Richard Wiseman in Paranormality it is. I've read Richard Dawkins on this and he reckons that all the senses stimulate the brain to construct virtual images - hence his hypothesis that bats may hear in 'colour', with 'colour' representing different textures.]

[Gordon]

It's information theory, developed in the 1940s in respect of telephones, but seemingly true of brains too. It's generally more efficient than processing everything.

Yes Mother Nature is a canny old bird, don't do more than you need!! She didn't produce scientifc instruments but an auditory system fit for purpose and that purpose may not have included music - as such - but natural sounds helpful to evolutionary survival!! musical appreciation is a bonus - or is it?? Discuss.

Information theory a mathematical construct developed by Bell Labs [the famous Claude Shannon "A Mathematical Theory of Communication" google for the book, ISBN 0 252 72548 4 - we stll use his "Limit" and of course his "bits" as a measure of information] when it was researching how to code and transmit messages for efficiency. Some of it goes back to the 20s and people like Harry Nyquist [yes, that one] which everyone has heard of!!

Also, remember that all wind instruments are based upon the harmonic series (since that's what you can produce without any keys) to which has been added half a ton of plumbing to produce the missing notes.

Yes and all that plumbing because the notes of the scales we use to play in all the keys don't actually fall nicely on the natural harmonics!! Hence, in keyboard instruments with fixed string lengths, the need for temperament. If you want a headache think about that - don't go there it'll hurt your brain!!

A similar thing happens with what we see. The brain can't process everything it senses without being many (many, many) times bigger. So it takes shortcuts. What seems like a flat expanse of colour is actually a response to the edge (the change) and many instructions to copy the new colour. The brain also makes assumptions based on what's happened before - presumably this is true also of sound, though I don't know.* This is what underlies much of why one person remembers things differently from another. It also explains many mistakes, since the brain makes wrong assumptions sometimes.

Fascinating stuff, particularly the fact that nothing we 'see' is actually real - it's all a virtual image constructed by our brain in response to stimuli from the eyes. I suspect there is an analogy there with hearing, but I'm not a neuroscientist.

*[According to Richard Wiseman in Paranormality it is. I've read Richard Dawkins on this and he reckons that all the senses stimulate the brain to construct virtual images - hence his hypothesis that bats may hear in 'colour', with 'colour' representing different textures.]

If you are interested in human visual system look up work by David Marr, sadly he died young - google him and lots of stuff will fall out. Whilst the visual system takes up a lot of brain space and also tries to be efficient, as a result it can be fooled - optical illusions [those constructed images mentioned above] are many, either in geometric terms - shapes that are ambiguous eg Escher - or like in colour TV which is one of the most interesting illusions of all.

Partly because we see a series of stills as movement [as in film of old shot at 24 frames a second which flickers] until there are enough and then we see continuous movement. Colour itself is a continuum of lightwaves at varous wavengths but the eye only sees 3 blocks of spectrum clustered on Red, Green and Blue wavelengths so that colour cameras only need use Red, Green and Blue sensors. On TV White is perceived but is a mix of 30% Red 60% Green and 10% Blue. Almost all the colours in nature can be made from these three - as far as the eye is concerned.

As for aural "images", yes, I suppose so we have a sense of space from hearing even with eyes shut as of course blind people do. How many aural illusions are there - can the ears be fooled like the eyes can eg stereo??

[Ferretfancy]

I think that the ears can be fooled, particularly because our aural memory is poor. I sometimes wonder whether animals with remarkable hearing ability like owls also have an acute memory to match. This would certainly give them an advantage when hunting their prey.

When I mixed documentaries I sometimes came across a difficult piece of poor quality sound which needed a lot of adjustment to make it acceptable, and ensure that it was a reasonable match for the material which was on either side. When we played the whole fifty minutes worth back later, nobody spotted the awkward sequence, time had passed and their memories had failed -sometimes conveniently for me !

This is one reason why I am skeptical about the claims made about the virtues of speaker cables etc. During subjective teats, if the interval that elapses while cables are swapped is long enough, maybe just a couple of minutes, the listeners will have forgotten the subtle differences they claim to have heard. Only an instantaneous change over will prevent this.

Regarding our colour vision, there is still a lot of mystery. Edwin Land, the inventor of the Polaroid process, devised a very interesting experiment using black and white panchromatic film. This registers the colours in a scene in shades of grey responding uniformly across the colour spectrum. He constructed a camera which held two plates which could be exposed simultaneously, but one image was shot through a yellow filter. After processing, the two images bearing a slight difference, but still black and white, were projected on to a screen with one image illuminated by yellow sodium light. When superimposed, the resultant picture was in full colour, even though the projected plates were black and white. Moreover if the yellow light source was transposed, the picture appeared in its complementary colours.

I have seen this demonstrated, but there is no really satisfactory explanation of how the eye and brain do it!

[EdgeleyRob]

MrGG, Pabmusic, RichardBarrett, Gordon, Ferretfancy.

Many, many thanks for taking the time and trouble to post such interesting replies.
Really appreciated.