programming with max/msp - Virtual Sound

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Chapter 1T - Introduction to sound synthesis No matter how strong the signal, we know that in order to double it, it will need to increase by 6 dB. Measurement in dB, in contrast to other measurements, is not absolute but relative; it allows us to measure and manipulate the relationship between one sound pressure level and another without knowing their absolute magnitudes. Here is a useful rule to remember: to reduce the magnitude of a signal by a factor of 10 (in other words, to reduce it to one tenth of the original amplitude) we must reduce the signal by 20 dB. Likewise, to increase a signal tenfold, raise it by 20 dB. It follows that an increase of 40 dB would increase a signal by 100 times, 60 dB by 1000, etc. For a more detailed discussion of this, see “Technical Details” at the end of this section. Let’s look at a table relating raw amplitudes, normalized to a maximum value of 1, to amplitudes measured in dB SPL. Amplitude dB SPL 1 0 0.5 -6 0.25 -12 0.125 -18 0.1 -20 0.01 -40 0.001 -60 0.0001 -80 0 -inf TABLE B: relationship between raw amplitude and dB SPL As we said, the deciBel is not an absolute magnitude, but is instead a relationship between two quantities, and so there is no absolute measure of 0 dB. Instead, you are free to define 0 dB as you wish, to use as a benchmark against which you will measure a given sound pressure. Unlike in digital audio, where we will usually specify that 0 dB is the maximum value reproducible in a given system, analog acousticians often use 0 dB to represent the minimum level for their amplitude scale, with positive numbers representing louder values. The following list itemizes, in an approximate way, pressure levels for some common environments (measured in dB at 1 meter of distance). Amplitude in this table, as you can see, is not represented using 0 dB as the maximum pressure level (as it would be in digital audio, where the amplitudes below the maximum possess negative values, such as -10 dB or -20 dB). On the contrary, these amplitudes are represented using 0 dB as a reference point for the “weakest perceptible sound,” leaving all other values to be positive numbers greater than 0. from “Electronic Music and Sound Design” Vol. 1 by Alessandro Cipriani and Maurizio Giri © ConTempoNet 2010 - All rights reserved 1T 15
1.2 16 Theory 8 140 the threshold of pain 130 a jet taking off 120 a rock concert 110 a symphony orchestra fortissimo 100 a truck engine 90 heavy traffic 80 a retail store 70 an office 60 normal conversation 50 a silent house 40 a night in the countryside 30 the rustle of leaves 20 wind 10 a light breeze 0 the weakest perceptible sound INTERACTIVE EXAMPLE 1B • AMPLITUDE amp amp amp amp � �� time in msec Paragraph 1.2 - Frequency, amplitude, and waveform Fig.1.14 Four sounds with their amplitudes progressively doubled from “Electronic Music and Sound Design” Vol. 1 by Alessandro Cipriani and Maurizio Giri © ConTempoNet 2010 - All rights reserved ��
Page 1 and 2: Alessandro Cipriani • Maurizio Gi
Page 3 and 4: Alessandro Cipriani • Maurizio Gi
Page 5 and 6: CONTENTS Foreword by David Zicarell
Page 7 and 8: Electronic Music and Sound Design -
Page 17 and 18: LEARNING AGENDA 1T PREREQUISITES FO
Page 19 and 20: 1.1 4 Theory sound or sounds that w
Page 21 and 22: 1.1 6 Theory ��
Page 23 and 24: 1.2 8 Theory Let’s look at a tabl
Page 25 and 26: 1.2 10 Theory time (by measuring th
Page 27 and 28: 1.2 12 Theory By the same reasoning
Page 29: 1.2 14 Theory If the amplitude of a
Page 33 and 34: 1.2 18 Theory 1000 Hz was chosen as
Page 35 and 36: LEARNING AGENDA 1P PREREQUISITES FO
Page 37 and 38: 1.1 52 Practice Paragraph 1.1 - Fir
Page 53 and 54: 1.2 68 Practice Paragraph 1.2 - Fre
Page 55 and 56: Interlude A PROGRAMMING WITH MAX/MS
Page 57 and 58: Interlude A - Programming with Max/
Page 65 and 66: 2T ADDITIVE AND VECTOR SYNTHESIS 2.
Page 67 and 68: Chapter 2T - Additive and vector sy
Page 73 and 74: 2P ADDITIVE AND VECTOR SYNTHESIS 2.
Page 75 and 76: Chapter 2P - Additive and vector sy
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Chapter 2P - Additive and vector sy
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LEARNING AGENDA 3T PREREQUISITES FO
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3.1 296 Theory dB Fig. 3.1 The spec
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3.1 298 Theory Paragraph 3.1 - Soun
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3.2 300 Theory Paragraph 3.2 - Lowp
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LEARNING AGENDA 3P PREREQUISITES FO
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3.1 358 Practice Make sure to try s
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3.1 360 Practice Fig. 3.6 The rand~
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3.2 362 Practice Paragraph 3.2 - Lo
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LEARNING AGENDA IB PREREQUISITES FO
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IB1 424 Practice defined to be the
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IB2 426 Practice From this example,
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LEARNING AGENDA 4T PREREQUISITES FO
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4.2 474 Theory In the example, the
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4P CONTROL SIGNALS 4.1 CONTROL SIGN
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Chapter 4P - Control signals 4.1 CO
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Chapter 4P - Control signals Under
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REFERENCES The decision was made to
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528 constructive interference, 190,
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530 multislider, 164, 179 multislid
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532 switch, 434, 468 T t (see trigg
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programming with max/msp - Virtual Sound

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