The Physics of Music

[fdeck]

I would say it's not particularly useful, and I'm a physicist. I was an "advanced student" musician long before I learned any real physics. But physics is one of those things where it can be useful, but in utterly unpredictable ways.

OTOH knowing how things work has saved me a boatload of money on gear.

Physics has also kept me from having to earn my living as a musician.

 

[Jim Carr]

...
Why do two notes an octave apart have the same name?
Why are there 12 different notes?
What do "equal temperament" and "just intonation" mean?
Why does a fifth sound "correct" at point A in tune B, but a flat fifth sounds horribly wrong?
Why does middle C played on a piano sound different to middle C on a guitar if they're the same note?

...What I'm interested in is your views on the extent to which a sound grasp of physical concepts like frequency and waveforms can support a person's musical development and help them understand the answers to questions like the examples above.

So, can understanding some aspects of physics help people learn about music?

IME, the help you seek for your students can not come from physics alone. For example, physics does not tell us why a 2:1 frequency ratio sounds the way it does to us, which features of a musical structure are significant, or why the noise transients in the attack of the contrabassoon matter more than the rest of the amplitude envelope of the harmonic partials for defining the instrument's timbre.

The fields you might enlist are music theory, music cognition (AKA psychoacoustics), and acoustics. Obviously, they all draw on physics, but the fact is that Pythagoras was writing about music theory when he first described harmonic partials, as observed at the blacksmith shop and with the monochord. Which field owns his work?

IMHO, a teacher needs to avoid erecting barriers. Expecting a student to understand octave equivalence before undertaking instrumental or vocal study is silly. A good teacher can explain enough of what is needed to allow the focus to be on making music. We may not know how much physics Charlie Parker, Ravi Shankar, Paul McCartney, or
Wolfgang Mozart understood, but I believe it was essentially irrelevant to their musical achievements.

 

[fdeck]

The fields you might enlist are music theory, music cognition (AKA psychoacoustics), and acoustics. Obviously, they all draw on physics, but the fact is that Pythagoras was writing about music theory when he first described harmonic partials, as observed at the blacksmith shop and with the monochord. Which field owns his work?

Up until a few hundred years ago, the field was called Philosophy.

 

[Ric5]

Understanding the physics of materials and the nature of electromagnetism helps me when building my own instruments.

 

[honestjohnny]

I would argue that an understanding of physics can be beneficial to most aspects of life, including, but not limited to, music. However, is it necessary to play and create complex, beautiful music? No.

 

[onlyclave]

Sorry, I have to rate this thread 0/10.

The art and language of music has nothing to do with physics. It has nothing to do with pickups, strings, amps, eq settings or any of the other things 99.7% the TB forums posts are about. It doesn't even have anything to do with an instrument.

If this thread was renamed "The Physics of Sound" I might think differently. Or perhaps "The Mathematics of Music", but trying to apply a left-brain quantization to a right-brained high art is the proverbial square peg/round hole.

If you're trying to somehow incorporate some kind of physics discussion into a music lesson then IMO you're just delaying and putting off the inevitable: The student should be doing more listening/transcribing/reading of the art.

 

[Joe Gress]

Yes.

 

[WalterBush]

The same rules for shaping sound in a room apply to an arranger, what effect you get when you combine the timbres of different instruments etc.

This. Theres not much difference, in my mind, between someone adjusting a mix at the soundboard, and a composer or arranger carefully writing down dynamics and articulation for a traditional orchestra.

While I'm not sure exactly why, for instance, listening to Bach pieces played in some kind of tempered tuning, and listening to the exact same pieces played in just-intonation, or some of the other tuning systems Bach messed with, yields entirely different results emotionally. Something just doesn't sound, 'right.' It still has to do with how pitch and frequency blend.

As well, middle-eastern instruments use entirely different tuning systems that just sound completely out of tune to the western ear, without an awful lot of ear training. The sounds coming out of some of those instruments sounds harsh and edgy to a lot of people, as well. Again, pitch, frequency, resonance. Until someone explained middle-eastern music of different styles to me a bit, it was all unenjoyable noise. I honestly thought they just couldn't afford instruments that would stay in tune.

Some countries, like Japan, are abandoning age-old tuning systems for our current twelve-tone system. I think it was a thread here where I first saw that Japanese educators were concerned that Japanese youth were growing up not understanding traditional Japanese music as a result.

All of it has to do with frequency, timbre, pitch, resonance, whether the instruments are acoustic or electric, amplified or not. Without at least some understanding of how sound is generated by instruments, I think most people default to what is 'easy' to listen to, i.e. what's on popular radio. Without some grasp of what goes in to creating music, by definition, people will listen to simpler, less creative, less complex, and less diverse styles of music.

So, yeah, some understanding of physics helps people learn about music. It can allow them to broaden their musical areas of interest, if they're willing.

 

[Jim Carr]

IME, the help you seek for your students can not come from physics alone. For example, physics does not tell us why a 2:1 frequency ratio sounds the way it does to us, which features of a musical structure are significant, or why the noise transients in the attack of the contrabassoon matter more than the rest amplitude envelope of the harmonic partials for defining the instrument's timbre.

The fields you might enlist are music theory, music cognition (AKA psychoacoustics), and acoustics. Obviously, they all draw on physics, but the fact is that Pythagoras was writing about music theory when he first described harmonic partials, as observed at the blacksmith shop and with the monochord. Which field owns his work?

IMHO, a teacher needs to avoid erecting barriers. Expecting a student to understand octave equivalence before undertaking instrumental or vocal study is silly. A good teacher can explain enough of what is needed to allow the focus to be on making music. We may not know how much physics Charlie Parker, Ravi Shankar, Paul McCartney, or Wolfgang Mozart understood, but I believe it was essentially irrelevant to their musical achievements.

Up until a few hundred years ago, the field was called Philosophy.

+1

Or at least one might have expected to study the Quadrivium (Music, Arithmetic, Geometry, Astronomy) in preparation for Natural Philosophy.

 

[jruberto]

maybe i'm splitting hairs, but those questions are much more around semantics and anthropology than physics.

but also... does learning all the minutiae about how a four-stroke engine works make you a better driver?

 

[Billnc]

maybe i'm splitting hairs, but those questions are much more around semantics and anthropology than physics.

but also... does learning all the minutiae about how a four-stroke engine works make you a better driver?

A guy who can wrench his own car may have an advantage, if he can set the car up to how he drives, and he knows why.

 

[Freddels]

There's a 2-DVD set you can get called Howard Goodall's Big Bang's Five Momentous Discoveries that changed the Course of Western Music. It has five shows that explain different things about music. One is Equal Temperament. Another is Recorded Sound. Another on Notation. It's very good and I highly recommend it.

 

[Ten Four One]

Why does a fifth sound "correct" at point A in tune B, but a flat fifth sounds horribly wrong?

i don't think that has anything to do with physics. but more to do with the eveolution of music and the "ear".

A fifth is the ratio 2:3. You can prove this for yourself.

How long is a bass string - 34" right? Measure the distance from the bridge to the 7th fret. It'll be about 22.5" - 2/3 the length of the string.

The 4th is 3/4 the length of the string - this is easy you can eyeball it. The 12th fret is 1/2, so take half of that and you land on the fifth fret (or the 24th fret if you go the other way).

Incidentally, the harmonics are located at these ratios - 1/2 (12th fret), 2/3 (7th fret) 3/4 (5th fret) for this very same reason. The string vibrates in a complex way & includes these sub-vibrations (called the overtone series) of 1/2, 1/3, 1/4, etc. of the string. If you play the full string & then lay your finger down at these points, you hear just the harmonic. Do it a few time and you'll begin to recognize the harmonic sound in the full string sound. (This is easiest to do with the 12th fret harmonic).

Do you really think it's a coincidence that the I, IV, V progression just happens to fall on the same frets the harmonics fall on? Do you really think that it's some trick of the ear that make us gravitate towards these tones & not some random other tones somewhere on the fretboard? It's physics.

The tritone is the ratio of 25:36. It sounds discordant because it's more complex, more chaotic. (fyi about 23.5")

A 2:3 ratio lines up every 6 pulses. A 25:36 ratio only lines up every few hundred pulses (225). You can rhythmically overlay a waltz (3/4) over a 4/4 and it'll sound interesting and maybe even beautiful. But lay a 25 pulse rhythm next to a 36 pulse rhythm and you have chaos. And just try to imagine a harmonic based on 25/36th the length of a string.

To say that 25:36 is dischordant because of a choice we made is like saying 4/4 is preferred as a drum beat over 13/4 because of some choice we made. No, 4/4 is preferred because it's the rhythm of walking - left right left right = kick snare kick snare. We don't gravitate towards songs in 13 because we have no basis for a 13 beat rhythm in the natural world.

We prefer the tempos we do because they're the tempos of walking & running. (ever fall into step with the music on your ipod? do you have workout music for the gym that's at a faster tempo?)

Up until a few hundred years ago, the field was called Philosophy.

Galileo & DaVinci (among others) have serious treatises on music. Galileo's father was a luthier & Galielo called the movement of the planets "the music of the spheres." You're welcome to classify Galileo's other works as "philosophy" too if you like.

As our understanding of music grew, so did the sophistication of the music. Think of the music of the middle ages - monks chanting in unison, or if they wanted to get fancy, the same melody, a fifth apart.



The 20th century saw a deconstruction of all of this. The blues, the electric guitar, recorded music, radio - all this contributed to a "dumbing down" of music. Once if you wanted to be a serious musician you understood the math behind music - it's pretty much the first chapter in music textbooks of the day. Just like modern music textbooks may start with "the major scale" - so did classic textbooks. Only they got into the WHY of the physics behind the major scale, whereas our textbooks just say "memorize these notes."

We don't need to know the physics behind music because the guitar (a fretted instrument with fixed note locations) alleviates of the "burden" of having to know why anything works. At the same time, it's approximations of real harmonies, while allowing us the freedom to move from key to key with ease, robs our ears of the richness real harmony, and is, I suspect, the reason so few of us sing - our ear has been cluttered with approximations & we don't hear the "lock" of pure harmonies the way our predecessors did. A fifth is no longer 2:3, it's a "good enough" approximation and this "good enough" sound means that when we sing along, there's nothing to "lock" onto, so our ears go unused to hearing the real harmonies of physics.

Also +1 Howard Goodal's DVDs, he's got a few different sets and they're all excellent. Highly recommended. Intended for the layman & easy to follow, they're very fun & educational.

 

[Ten Four One]

maybe i'm splitting hairs, but those questions are much more around semantics and anthropology than physics.

but also... does learning all the minutiae about how a four-stroke engine works make you a better driver?

Depends on if you're getting to work or winning the Indy 500. Knowing when to expect extra torque, knowing why wind drag keeps your car on the ground at 200mph, knowing at what temperature the rubber in your tires starts to give out - all this stuff helps win races.

The driver isn't necessarily doing math in his head he's just thinking "it's hot out & here's a strong headwind, I should stop in the pit more frequently to change the tires."

 

[GlennPagano]

Okay, thanks - would you mind saying what physics you studied before starting your current course? Your description of octaves made me a little curious.

I just took a AP physics B in High School and that taught me a lot about waves, both light and sound. I was interested in it so i did a little more research on my own (look up physics of music on google). Right now in college I am taking Geneds and will be taking calc based physics course next semester but this still does not include any wave type stuff. At my college I know that all music majors are required to take a physics of music class and I am considering taking that up. No real formal teaching of how waves are related to music. I know enough about them to infer and apply them to music.

In my opinion it is interesting to learn, but almost useless on a practical level. There are just too many basic philosophical questions unanswered to draw any real helpful conclusions. For example, we know that there is a relation between a fifth over a root "sounding good" and the fact that the frequency of the waves follow a fairly even pattern with each other. But we can't say WHY waves with even patterns sound good to us once our brain registers them. We can't say why certain waves will sound good to us in one timbre, but not in another. Or in one situation, and not in another. It all goes back to the mind/body problem really.

Really, the most important aspect of physics a musician should know is how too loud of a volume effects you and the crowd's ears.

I agree with this 100%

 

[fdeck]

At my college I know that all music majors are required to take a physics of music class and I am considering taking that up.

If you have breezed through calc based physics, then the physics of music class might be a bit on the light side for you. Dare I suggest...

Look around for something a bit more geeky -- not for any sort of career goals, but just for fun. Maybe continue further with the math, or take a course in electronics or digital signal processing if it is offered. If there's no engineering school, the physics department probably offers electronics. These are not fundamental to music, but they certainly have their uses!

For a glimpse at what you can do with relatively elementary math / physics, take a look at my speaker theory paper at my little web page.

 

[GlennPagano]

If you have breezed through calc based physics, then the physics of music class might be a bit on the light side for you. Dare I suggest...

Look around for something a bit more geeky -- not for any sort of career goals, but just for fun. Maybe continue further with the math, or take a course in electronics or digital signal processing if it is offered. If there's no engineering school, the physics department probably offers electronics. These are not fundamental to music, but they certainly have their uses!

For a glimpse at what you can do with relatively elementary math / physics, take a look at my speaker theory paper at my little web page.

Yea thats the only reason why I might not take the physics of music class. Where did physics end up taking you? What career do you have now?

 

[hbarcat]

Sorry, I have to rate this thread 0/10.

The art and language of music has nothing to do with physics. It has nothing to do with pickups, strings, amps, eq settings or any of the other things 99.7% the TB forums posts are about. It doesn't even have anything to do with an instrument.

If this thread was renamed "The Physics of Sound" I might think differently. Or perhaps "The Mathematics of Music", but trying to apply a left-brain quantization to a right-brained high art is the proverbial square peg/round hole.

If you're trying to somehow incorporate some kind of physics discussion into a music lesson then IMO you're just delaying and putting off the inevitable: The student should be doing more listening/transcribing/reading of the art.

I rate this thread 10/10.

Physics in music is abundant and knowledge of this has greatly enhanced not just my abilities as a musician but also my appreciation of music. But that's just me. Many musicians happily put out fine music without the slightest understanding of the physics of their craft, nor do they wish to bother with it.

 

[hbarcat]

does learning all the minutiae about how a four-stroke engine works make you a better driver?

Most definitely.

Understanding the physics of vehicle aerodynamics and friction will help me to improve my fuel economy if that's what I want to achieve. Working out the best fuel economy by trial and error is a very slow and uncertain way to get there. Figuring out optimum vehicle efficiencies on paper first gives you a big head start.

This is far more important for those who participate in auto racing. Learning the fastest way around a track by trial and error is a sure way to lose. There are optimum lines around a track that can be calculated with physics. Knowing when to brake before entering a turn and at what speed to take the turn and when to accelerate out of the turn is where races are won or lost, and the application of a little bit of calculus gets the driver the answer a lot faster than relying on intuition.

Applied to myself as a bass player, understanding how notes sound different with a different dynamic attack helps me play better if I use that knowledge to adjust my technique, just as one example. Another is how I set up, intonate and tune my basses.

I first read the textbook "The Science of Sound" by Prof Rossing a couple of years ago, and the physics of music that I learned in it was like the metaphorical revelation to me and it caused me to make a lot of adjustments in my playing and my approach to music. Yet, I would still be a decent bass player if I had never read it and it's true most musicians couldn't care less about such stuff, including some of the greatest musicians in the world. But I can only speak for myself, and I know how useful it is to me.

 

[BassyBill]

Thanks for the very civil discussion, folks. Very interesting responses.

My opinion, fwiw - yes, understanding how an engine works can most certainly make you a better driver. But to answer the question properly, perhaps you only need a broad understanding, rather than the minutiae.

I think the people who have said that an understanding of physics is somehow irrelevant to the art of music are missing something, even if what they're missing is just an aesthetic appreciation of the elegance of physics. They might find "Unweaving the Rainbow" by Richard Dawkins a thought-provoking read.

I also think, though, having read all your posts, that some people would be able to benefit from such an understanding and apply it to their musical learning, whilst others might find it actually got in the way.

Freddels - that DVD recommendation sounds just the sort of thing I'd enjoy, thanks for that.