One part of music’s soul: physics


Welcome to BrainSnacks! Have you ever asked yourself what music
actually is? I mean in terms of physics. I don’t want to ruin the romance and fun of
music of course, but the explanation how music actually works might give you
another viewpoint on it or “hear point”. Here are some music / acoustic basics. If
someone sings a tone or plays it with an instrument, the air molecules around
start oscillating. They do it in a periodical way so the oscillation can be
described with an acoustic wave. One of the most important characteristics of an
acoustic wave is its frequency. It indicates how often the wave occurs in a
certain amount of time. Also the period of a wave is important. It is the time
needed for one cycle of the wave and the relationship between the frequency and
the period is reciprocal. For example: wave 1 occurs two times in one second
and wave 2 occurs four times in one second. So wave 1 has a frequency of two
per second and a period of a half second and wave 2 has a frequency of
four per second and a period of 1/4 of a second. The unit per second is also
called Hertz. A piano has tones from approximately 16 to 5500 Hertz and the
higher the frequency the higher is the tone. Let’s listen to some cords now and
for that I asked two very talented singers to join me. Hi I’m Simon!
Hey I’m Moritz. One, two, three… But the question arising is: why do these
courts sound so good for our ears? So each tone has a different frequency and
if they’re played or sang together the acoustic waves of the single tones
influence each other and they form a new wave that is the superposition of the
single waves. Let’s look at the example of my left: the two tones are a C and an
E. This musical interval is called a third.
An acoustic wave that corresponds to a note of that C has a frequency of 132
Hertz and that E has a frequency of 165 Hertz. So the frequency of E is the
frequency of C times 5/4, that means that the superposed wave will repeat every 4
periods of C or every 5 periods of E and as you can see it has a regular pattern.
Our ears really like regular stuff so that is why it sounds so good.
It is similar with a C and a G played or sang together. The interval between these
notes is called a fifth. The frequency of G is the frequency of C times
three-halves, so the superposed wave repeats after two periods of C or three
periods of G as you can see also this pattern looks pretty regular and
therefore the two notes played together sound good. One example for a wave
pattern that it’s not so regular is that one of a tritone formed for example with a
C and an F-sharp. Aou hear immediately that it doesn’t sound so nice. The
frequency ratio of these notes is 45 to 32 that means that the pattern just
repeats every 32 periods of C or every 45 periods of F-sharp and that explains
the not so pleasant sounding interval. The cords we sang on the beginning of
this episode were major courts and they always consist of a root for the chord
a third and the fifth. The superposed waves form a regular pattern and that is
why the cord sounds good. Makes sense right? I hope you enjoyed
watching this video, this topic was completely new to me, I just studied some
theory of harmony playing the piano but I never looked at the math and physics
of it. Please let me know in the comments if you would like me to do more videos
about this topic or write an email to [email protected] . I find it
really interesting and fascinating so let me know if you share my excitement.
You can also follow BrainSnacks on Facebook, Instagram and Twitter and
the links are in the description of this video. I also want to thank Moritz and
Simon for helping me with this video, I had a lot of fun and if you want to see
more of them they have some really cool bands. Simon’s band is called Cosmo Super
and move it’s band is called Zaunkönig and the links are in the
description of this video. This was Clara from BrainSnacks! Bye Bye!!