Introduction to Digital Sound Design (Coursera, February 2013)
Introduction to Digital Sound Design
Coursera, https://www.coursera.org/course/digitalsounddesign
Taught by Steve Everett (Emory University)
Week 1: The Nature of Sound
in the ear, physical phenomenon is being translated to electrical pulses, which are then interpreted by our brain
attributes of sound perception:
1) pitch -- frequency of how often air is being compressed; we can perceive ~16-20k vibrations per second
2) loudness (amplitude); height of the compression determines amplitude; not how fast they're going (which is pitch) but their intensity
3) timbre (color or quality of sound; multiple vibrations of different amplitudes, interpreted as color of sound); when you hear a singing tone, you're hearing multiple different pitches that the brain interprets as one
4) duration (length); not fixed, but something we perceive; our sense of "slowness" vs "fastness" tends to be relative to our heartbeat
5) articulation or "envelope" of a sound; first few milliseconds of a sound, it's attack, changes with ifferent instruments
6) diffusion, or sound spatialization; our brain is able to interpret where sound is coming from; different channels (e.g. 10.2 surround sound)
overtone series (also called harmonic or partial series): simultaneously sounding off a particular fundamental frequency (the pitch we hear) plus divisions of it in ratios
when a cello string is plucked, the whole instrument vibrates; we're getting many different frequencies that our ear is processing collectively as the cello
spectrum of the voice -- can identify which frequencies are most prominent (stronger partials)
2/1, 3/1, etc. ratios in the overtone series; all are vibrating at once in a cello to create its timbre (even though we don't hear them individually)
can have quick aesthetic responses based on our experience of timbre
synthesizing sound is building up timbre through addition of different frequencies
sheet music as representation of music, but also a set of instructions for the body, a set of kineaesthetic instructions
music and evolution
- has promoted group cohesion
- socio-emotional bonding
- promotes sexual selection
music in emotional and cognitive development
- 2 mo old -- prefer consonant to dissonant
- 2 year old -- recognize happy sounds
- by age 5 can detect pitch
- by age 6, can detect both key and harmony
- tonality fully developed by age 9-12
infants are able to detect mother's timbre even in a crowd
white noise quiets an infant; possibly because of white noise heard in womb (blood rushing, etc.)
auditory roughness -- high ratio partials, highly unstable, pitch instability; concept introduced by Helmholtz (1885)
example of roughness: opening guitar of Jimi Hendrix's "Purple Haze"
how do different cultures develop different preferences for auditory roughness?
Sonic Visualiser, sonicvisualiser.org