When you play a single note on a piano, you are not actually hearing just one frequency.
You hear a fundamental pitch together with a series of higher frequencies called overtones or partials.
Those frequencies are one of the reasons a piano sounds like a piano, a flute sounds like a flute, and the same written note can have a completely different color depending on which instrument plays it.
And, strangely enough, this is also how we ended up inventing the Sasquatch chord.
One Note Contains Many Frequencies
Suppose we play a low B♭ on the piano.
The lowest and strongest pitch gives us the note we identify as B♭.
But above that fundamental, the sound also contains higher-frequency components.
The first few harmonic relationships are approximately:
B♭ → B♭ → F → B♭ → D → F …
So very early in the harmonic series we encounter:
- the root
- another root an octave higher
- the perfect fifth
- another octave
- the major third
That is why the overtone series has such an important relationship to harmony.
Hidden inside the spectrum of a single musical tone are intervals that resemble the building blocks of chords.
Harmonic Series vs. Overtone Series
These terms are often used almost interchangeably, but technically there is a small distinction.
The harmonic series usually includes the fundamental frequency itself.
The overtone series refers to the frequencies above the fundamental.
So if the fundamental is the first harmonic:
- 1st harmonic = fundamental
- 2nd harmonic = 1st overtone
- 3rd harmonic = 2nd overtone
- and so on
For practical musical discussion, the important idea is simply that a complex musical tone contains many related frequencies at the same time.
Why a Piano and a Flute Sound Different
If two instruments play the same pitch, why don’t they sound identical?
Because the overtones are not equally strong.
Each instrument emphasizes the partials differently.
A piano might have a particularly strong octave or fifth partial, while another instrument might emphasize a different part of the spectrum.
That pattern of relative amplitudes contributes enormously to what we call timbre.
So timbre is not simply:
“This is a piano.”
At the acoustic level, it is partly the result of which frequencies are present and how strong they are relative to one another.
You Can Hear the Overtone Series on a Piano
One of the most interesting demonstrations in the lesson uses sympathetic resonance.
Hold down a higher B♭ silently so its damper lifts from the strings.
Then strike a lower B♭ and release it.
The higher B♭ begins to resonate.
Why?
Because that higher pitch is strongly represented in the harmonic spectrum of the lower B♭.
The same thing can be demonstrated with the F above it.
But if you silently release the damper of a note that has little relationship to that particular part of the harmonic spectrum, it will not resonate nearly as strongly.
This lets us experience the harmonic series physically rather than merely looking at a diagram.
The piano itself becomes the experiment.
Seeing Overtones in a Spectrum
We can also record the B♭ and examine it with a spectral analyzer.
Instead of seeing only one frequency, we see a stack of frequency bands.
The fundamental is present, but so are higher partials corresponding approximately to the harmonic series.
And the bands have different intensities.
That visualizes the same phenomenon we heard through sympathetic resonance:
one piano note is actually a composite sound.
This is also why saying that a note is “just B♭” is useful musically but incomplete acoustically.
Does Every Note Contain a Major Chord?
The lesson makes a deliberately provocative observation:
In a sense, every time you play a note, you are already hearing the ingredients of a major triad.
The early harmonic series contains the root, fifth, and eventually the major third.
For B♭, those pitch classes are:
B♭ – D – F
So the spectrum begins to reveal something very close to a B♭ major triad.
That does not mean that every played note is literally a major chord in the normal harmonic sense.
The partials have different amplitudes, occupy different octaves, and are properties of one complex tone rather than independent chord voices.
But it does reveal something profound:
many familiar consonant intervals are already embedded in the acoustics of musical sound.
That is the real theoretical insight hiding inside the joke.
And This Is Where Bigfoot Enters the Story
The Crypto Chords premise was intentionally ridiculous:
take mysterious phenomena and search for hidden musical structures using music theory, numerology, spectral analysis, and whatever other questionable investigative techniques seemed entertaining.
For Bigfoot, the chain of “evidence” goes something like this:
- the creature is called Bigfoot
- the recorded cry seems to center around B♭
- “Bigfoot” has seven letters, so obviously it must be a seventh chord
- Bigfoot is also called Sasquatch
- therefore the chord must somehow be a sus-quatch
None of this is intended as scientific evidence.
It’s the comic framework that gets us to the actual theory.
What Is a 7sus4 Chord?
Before creating the mythical Sasquatch chord, we need a real chord.
A B♭7 chord is:
B♭ – D – F – A♭
or:
1 – 3 – 5 – ♭7
A B♭7sus4 replaces the third with the fourth:
B♭ – E♭ – F – A♭
or:
1 – 4 – 5 – ♭7
The word suspended comes from the traditional tendency of the fourth to resolve down toward the third.
That gives us the perfectly respectable theoretical starting point for the completely disreputable Sasquatch chord.
The Strange Frequency in the “Bigfoot” Recording
The lesson then analyzes the alleged Bigfoot recording spectrally.
If the fundamental is B♭, we would normally expect strong early partials related to:
B♭ and F
But the recording appears to contain a prominent E natural where F would have been the more expected relationship.
Enharmonically, E can be spelled F♭ relative to B♭.
And F♭ is:
♭5
So the investigation turns the ordinary:
B♭7sus4
into:
B♭7sus4(♭5)
with:
B♭ – E♭ – F♭ – A♭
The acoustical analysis is real as a technique; using it to deduce Bigfoot’s personal chord vocabulary is, obviously, the joke.
Lower Structures and Upper Structures
At this point the lesson moves into another genuinely useful jazz-harmony concept:
upper structures.
Complex voicings can often be understood more easily as combinations of simpler chordal units.
Instead of thinking:
“I have to memorize nine unrelated notes,”
we can think:
“Here is one lower structure, and here is another recognizable structure above it.”
The imaginary Sasquatch chord becomes an excuse to push this idea to an extreme.
Its lower structure begins with the B♭7sus4(♭5) sound.
Then additional upper structures are layered above it until the chord becomes deliberately enormous.
The Final Sasquatch Chord
On piano, the lesson constructs the full sonority from two hands.
The lower structure contains the essential:
B♭ – E♭ – F♭/E – A♭
which gives us the:
1 – 4 – ♭5 – ♭7
sound.
The upper structure then adds more color tones, including a G-based dominant structure and additional notes chosen partly through the Crypto Chords narrative.
The result is not a standard chord symbol you are expected to encounter in a Real Book.
It is an invented sonority.
And that’s precisely the point.
Once you understand:
- chord construction
- suspensions
- altered fifths
- overtones
- tritones
- upper structures
- voicing
you can begin designing sounds, rather than merely identifying chords someone else already named.
Why the Joke Actually Works as a Music-Theory Lesson
This is the part I would emphasize strongly in the article, because I think it explains why the video is more substantial than it initially appears.
The ridiculous chain of reasoning is constantly moving through real concepts:
Bigfoot recording
↓
pitch identification
↓
spectral analysis
↓
overtone series
↓
sympathetic resonance
↓
timbre
↓
major-triad relationships in the harmonic spectrum
↓
sus chords
↓
altered chord tones
↓
upper structures
↓
voicing
So the bizarre narrative is doing something pedagogically clever:
it gives unrelated-looking theoretical concepts one continuous problem to solve.
You keep asking “What chord is Bigfoot?” and accidentally learn acoustics and advanced harmony along the way.
What the Overtone Series Really Teaches Us
The most important takeaway has nothing to do with Bigfoot.
A musical note is not an isolated frequency.
It is a structured spectrum.
That spectrum affects:
- timbre
- consonance
- instrument color
- resonance
- interval perception
- and, indirectly, many of the harmonic relationships musicians use every day
The overtone series therefore sits at an interesting meeting point between:
physics and harmony.
It explains something about both what sound is and why certain collections of notes can feel so naturally related.
Key Takeaways
The overtone series is the collection of frequencies above a fundamental that contribute to a musical sound.
Its early partials produce relationships such as:
- octave
- perfect fifth
- another octave
- major third
The relative strength of those partials helps determine an instrument’s timbre.
You can demonstrate them physically through sympathetic resonance or visually through spectral analysis.
And once you start treating those acoustic relationships as musical raw material, they can lead naturally into:
- chord construction
- voicing
- upper structures
- altered harmony
Or, if you are sufficiently irresponsible:
a B♭7 Sasquatch chord.
mDecks Music 
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