What is Sound? Part II

Transcription

1 What is Sound? Part II Timbre & Noise 1 Prayouandi (2010) - OneOhtrix Point Never

2 PSYCHOACOUSTICS ACOUSTICS LOUDNESS AMPLITUDE PITCH FREQUENCY QUALITY TIMBRE 2

3 Timbre / Quality everything that is not frequency / pitch or amplitude / loudness envelope - the attack, sustain, and decay portions of a sound spectra - the aggregate of simple waveforms (partials) that make up the frequency space of a sound. noise - the inharmonic and unpredictable fluctuations in the sound / signal 3

4 4 envelope

5 envelope ADSR 5

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7 7 Frequency Spectrum

8 8 Spectral Analysis

9 9 Additive Synthesis

10 10 Organ Harmonics

11 11 Spectral Analysis

12 Cancellation and Reinforcement In-phase, out-of-phase and composite wave forms 12 (max patch)

13 13 Tone as the sum of partials

14 harmonic / overtone series the fundamental is the lowest partial - perceived pitch A harmonic partial conforms to the overtone series which are whole number multiples of the fundamental frequency(f) (f)1, (f)2, (f)3, (f)4, etc. if f= , 220, 330, 440 doubling = 1 octave An inharmonic partial is outside of the overtone series, it does not have a whole number multiple relationship with the fundamental. 14

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17 Basic Waveforms fundamental only, no additional harmonics odd partials only (1,3,5,7...) 1 / p 2 (3rd partial has 1/9 the energy of the fundamental) all partials 1 / p (3rd partial has 1/3 the energy of the fundamental) only odd-numbered partials 1 / p (3rd partial has 1/3 the energy of the fundamental) 17 (max patch)

18 18 Spectrogram (snapshot)

19 19 Identifying Different Instruments

20 20 audio sonogram of 2 bird trills

21 Spear (software) audio surgery? isolate partials within a complex sound 21

22 the physics of noise Random additions to a signal By filtering white noise, we get different types (colors) of noise, parallels to visible light

23 White Noise White noise is a random noise that contains an equal amount of energy in all frequency bands. White light is made up of all light frequencies (colours), while white noise is made up of all audio frequencies. White noise is used in electronic music, either directly as a sound effect or as the basis to create synthesized sounds. White noise is also used to mask other sounds the brain is able to single out simple frequency ranges but has trouble when too many frequencies are heard at once. When white noise is present, other noises appear diminished.

24 Pink Noise Pink noise is a random signal, filtered to have equal energy per octave. In order to keep the energy constant over octaves, the spectral density needs to decrease as the frequency (f) increases. This explains why pink noise is sometimes referred as "1/f noise." In terms of decibels, this decrease corresponds to 3 db per octave. The name of the color comes from visible light that turns pink when a similar spectral distribution is applied.

25 Brown (Red) Noise Brown noise is a random signal that has been filtered in order to generate a lot of energy at low frequencies. The "brown" name comes from the "brownian" movement, not the color. Brownian noise is also referred to as red noise. Visible light turns red when a similar spectral distribution is applied. Brown noise is obtained by running the same filter on pink noise, as the one used to turn white noise into pink noise. Brown noise offers the same bias toward the lower frequencies, as white noise does toward the higher frequencies.

26 Grey Noise Although white noise plays equally loudly at all frequencies, because of psychoacoustic properties, it fails in giving the listener a balanced perception. White noise can be passed through a filter, which inverts our frequency sensitivity curves (Fletcher- Munson Curves), to create grey noise, a noise that feels perceptually flat. Grey noise and white noise would be the same if our ears were equally sensitive to all frequencies in the audible spectrum.

27 Tristan Perich - Microtonal Wall