CHAOS & ORDER
HISTORY OF ACOUSTICS
HARMONICS & TIMBRE
FILTERS/EQ/RESONANCE
“Legend recounts how Orpheus was given a lyre by
Apollo...by playing his lyre, Orpheus produced harmonies
that joined all of nature together in peace and joy. Inspired by
this Orphic tradition of music and science, Pythagoras of
Samos conducted perhaps the world’s first physics
experiment. By playing strings of different lengths, Pythagoras
discovered that sound vibrations naturally occur in a
sequence of whole tones or notes that repeat in a pattern of
seven. Like the seven naturally occurring colours of the
rainbow, the octave of seven tones".
‘The Harmonic Lyre’ by Stephen Ian McIntosh
AURIGNACIAN FLUTE MADE FROM AN ANIMAL BONE,
GEISSENKLÖSTERLE (SWABIA),
ABOUT 43,000 YEARS OLD.
Harmony of the Spheres
Bianzhong of Marquis Yi of Zeng
(simplified Chinese: 曾侯⼄编钟; traditional Chinese: 曾侯⼄編鐘; or Zenghouyi Bells, were bianzhong
unearthed in 1978 in the Zeng-hou-yi Tomb in Sui County, Hubei Province, China, made in 433 B.C.
https://www.youtube.com/watch?v=zhcCSeRj2PU
Cymatics
Patterns of Sound in Liquids
Patterns of Sound
in Solid Objects
Ratios
Harmonic overtone singing
ANNA-MARIA HEFELE
https://www.youtube.com/watch?v=UHTF1-IhuC0
Indian Ragas
https://www.youtube.com/watch?v=5bFzS6upIW4
Tibetan Monks
https://www.youtube.com/watch?v=NW13mUjoeks
Documentary on rhythm, featuring the drumming and
songs of the West African Malinke people.
h;ps://www.youtube.com/watch?v=lVPLIuBy9CY
Timbre
In psychoacoustics, we characterize sounds by
> Pitch, > Loudness, and > Timbre (or quality).
Timbre allows us to distinguish sounds even if they
have the same pitch and amplitude. For example:
Sine wave 110Hz
Square wave 110Hz
Timbre is mainly determined by:
> The spectral content of a sound (harmonic frequencies)
> The dynamic characteristics of the sound (vibrato)
> The envelope of a sound (Attack|Decay|Sustain|Release)
As light can be decomposed in its various constituents
(using a prism), sound can be decomposed into individual
frequencies (sine waves)
Sound can be analyzed using the “Fourier Theorem”:
All waveforms can be seen as a sum of sine waves
(frequency, amplitude and phase)
This gives us an alternative way to represent sound:
> For each frequency, we will indicate what intensity the
sine wave of that frequency would be
> This gives a snapshot representation of the sound
according to the various frequencies present at a given
moment (or throughout time) called a spectrogram
Spectral analysis is done with the Fourier transform:
The spectrogram is the visual representation of
the frequency spectrum
> Fundamental frequency: the lowest resonant
frequency of a vibrating object. It is usually what is
perceived as being the pitch. For a periodic waveform, it
is its frequency.
> Overtones: the term overtone refers to any resonant
frequency above the fundamental frequency (including
those defined as harmonics)
> Harmonics: overtones in simple ratio multiples of the
fundamental frequency. Most vibrating objects have
more than one resonant frequency and those used in
musical instruments typically vibrate at harmonics of the
fundamental
> Formant: region of concentration of energy
Harmonic Sound
Frequency spectrum of a trumpet playing a A4
Inharmonic Sound
Frequency spectrum of a metal chime
Inharmonic Sound
Some sounds do not exhibit clear sinusoidal modes
(harmonic components). Pitch can’t be easily idenitifed.
Spectral Analysis
Evelyn Glennie What Do Artists Do All Day ?
https://youtu.be/rEuZ3B9B4HA
Filters
> An audio filter is a frequency dependent amplifier circuit, working in the audio
frequency range, 0 Hz to beyond 20 kHz.
>In its most basic form, an audio filter is designed to amplify, pass or attenuate
(negative amplification) some frequency ranges.
>Common types include low-pass filters, which pass through frequencies below
their cutoff frequencies, and progressively attenuates frequencies above the cutoff
frequency.
> A high-pass filter does the opposite, passing high frequencies above the cutoff
frequency, and progressively attenuating frequencies below the cutoff frequency.
> A bandpass filter passes frequencies between its two cutoff frequencies, while
attenuating those outside the range.
>A band-reject (notch) filter, attenuates frequencies between its two cutoff
frequencies, while passing those outside the 'reject' range.
EQ Explained
Sound Basics with Stella
https://youtu.be/I6ZF_NHvqzU
Low Pass
Parametric EQ
Multiple EQs
EQ/Filters in Audacity
Daft Punk - Revolution 909
Boards of Canada - Alpha and Omega
ACOUSTIC FILTERS: MUTES
Acoustic Filters: Mutes
Cup
Wah-wah
(Harmon)
Plunger
Miles Davis - It Never Entered My Mind
Resonance
Acoustic Amplification
It is easy to get an object to vibrate at its resonant
frequencies, hard to get it to vibrate at other frequencies.
A vibrating object will pick out its resonant frequencies from a
complex excitation and vibrate at those frequencies, essentially
"filtering out" other frequencies present in the excitation.
“EIGENTONE”
Alvin Lucier’s - I Am Sitting In a Room
https://www.youtube.com/watch?v=fAxHlLK3Oyk
For next Week
Please read:
How Music Works - By David Byrne