NOTE: The MIT Press released a second printing of Musimathics Volume 1 midSeptember, 2008 that fixed all errata in the first printing of Volume 1 as of 7/15/2008. I have started a new table for errata that have appeared since the Second Printing. of V1, below. Though there have been additional printings since that time, there have been no further corrections to the printed text. So if you have a more current printing, you should still consult the Second Printing errata.
Errata for Musimathics Volume 1 are different depending on which printing you have. Look at the bottom of the Copyright page. If the bottom of the Copyright page reads:
“10 9 8 7 6 5 4 3 2 1”, then you have the First Printing,
“10 9 8 7 6 5 4 3 2”, then you have the Second Printing.
The third, forth, etc. printing simply lop off the final digit. For any higher printing you should still consult errata for the Second Printing.
Volume 1 – Musical Elements 
Volume 2 – Musical Signals 

Dr. Gareth Loy Rewards for Reporting Errata! 
Musimathics Volume 1 Errata – Second Printing 

Location 
Problem 
Correction 
p. 5 
Correction 
The sentence leading from the bottom of page 4 to page 5 is incorrect. It reads, “The spring begins to go slack as the mass rises, and when the mass reaches the equilibrium point, the spring no longer lifts the mass upward.” It should read instead, “The spring begins to go slack as the mass rises, and when the mass reaches the equilibrium point, the force due to gravity is greater than that of the spring.” 
p. 17, 2.4.2 1^{st} para. & Fig. 2.3 
Solmisation syllable “ti” vs. “si”. 
Solmization syllables in English countries use “ti” for the 7^{th} degree while many other countries use “si”. The text and figure should have a footnote explaining this regional difference. (Strictly speaking, not an erratum.) 
p. 19 Table 2.1 
The number of semitones should not be shown for Augmented & Diminished intervals. 
Yes, the augmented fourth and diminished fifth each have 6 semitones, but because these terms can be applied to other intervals as well, this is confusing. It would be better either not to indicate the number of semitones for Augmented and Diminished, or perhaps to give “+1” and “1” for them to indicate that they add or subtract a semitone to the named interval, respectively. 
p. 20 
Correction 
Text reads, “The Lochrian mode is purely a theoretical mode, considered unusable by conventional music theory because of the tritone that exists between its final (7) and its fourth degree.” Text should read, “The Lochrian mode is purely a theoretical mode, considered unusable by conventional music theory because of the tritone that exists between its final (I) and its fifth degree (V).” 
p.22 Fig 2.10.b 
Typo in figure 
Pitch labeled “B” should be “Bb” (“Bflat”). 
p. 23 Fig. 2.12 (b) 
Alignment in figure. 

p. 24 Fig. 2.14 
Additional information 
The printed spelling of the pentatonic scale shown in Fig. 2.14 is just one of several modes (circular permutations) of the scale's intervallic sequence, {2, 3, 2, 2, 3} discussed on page 23; there is no “official” pentatonic mode, and one is as good as another so long as the interval order is preserved. If I had it to do over again, I might have chosen the mode {2, 2, 3, 2, 3}, as it outlines a major triad in root position. 
p. 24 Fig. 2.15 
Typo 
Pitch labeled “A” should be labeled “Ab” (“Aflat”). (Note, this erratum incorrectly used to refer to Fig. 2.14. Heavens, an erratum in my errata!) 
p. 26 Table 2.3 
Whole note rest is incorrect 
The way I learned it in school, the wholenote rest “hat” is “off”, and the halfnote rest “hat” is “on”. Evidently, I need to go back to school on this one. The wholenote rest should look like this:

p. 31 Fig. 2.21 
Typo 
Topleft text reads “Fundamental 1”, should read just “Fundamental”. 
p. 34 
Fig. 2.24 
Instrument plot from Grey 1975 is probably an Eb clarinet tone, not a stringed instrument tone. 
p. 42 just before Sec. 3.2.2 
Arguments to function f are reversed. The function is defined on page 41 bottom as f(k,v), but the examples of use on page 42 reverse the arguments: f(v,k). For example, the text reads, “A0 = f(0,9)” but should read “A0 = f(9,0)”. 
Here are the function arguments as shown in the text:

p. 43 
Correction 
Text reads: “We can use equation (3.1) to add and subtract intervals. If k = 2 in that equation, then frequency f_{k} will be two octaves above frequency f_{R}.” Text should read: “We can use equation (3.3) to add and subtract intervals. If v = 2 in that equation, then frequency f_{k,v} will be two octaves above frequency f_{R}.” 
p. 46 first full paragraph 
Correction 
Text reads, “So the tempered fifth is almost 2 cents flat of a perfect fifth.” Text should read, “So the tempered fifth is almost 2 cents flat of a just fifth.” 
p. 118 first ¶ after sec. 4.22, 2^{nd} sentence 
Incorrect word 
Text reads: “Intensity I is the energy E per unit of time t that is flowing across a surface of unit area a” Delete “unit”, since intensity is the power in the area a, whatever its size. Text should read: “Intensity I is the energy E per unit of time t that is flowing across a surface of area a” 
p. 118 Eq. 4.34 
Incorrect term in equation 
The denominator should be a, not a^{2}. We divide power by the area, not the square of the area. The equation could then be more simply expressed: I = E/t/a. 
p. 118 Text line just below eq. 4.34 
Incorrect term in equation 
Inline equation reads: “I=P/a^2”, but should read “I=P/a” to correct the derivation from the revised Eq. 4.34. 
p. 119 first ¶ 
Improvement 
Text reads: “Let P be the power of a wave at distance r_{1} propagating along direction V. This means that an amount of energy P is flowing through surface a_{1} each second. If no energy is lost, then the same power will flow through a_{2} each second as well, and P/a_{1} = P/a_{2}. Since the areas of surfaces a_{1} and a_{2} are proportional to the squares of their distances from the source S, the intensity I varies inversely as the square of the distance to the source...” Substitute: “Let P be the power of a wave at distance r_{1} propagating along direction V. This means that an amount of energy P is flowing through surface a_{1} each second. If no energy is lost, then the same power will flow through a_{2} each second as well, so total power P at a_{1} would be the same as at a_{2}. However, since the areas of surfaces a_{1} and a_{2} are proportional to the squares of their distances from the source S, the intensity I varies inversely as the square of the distance to the source...” 
p. 119 Eq. 4.37 
Incorrectly identifies unit for unitless ratio 
Eq. 4.37 expresses the ratio of (limit of hearing)/(threshold of hearing) in units of W/m^{2}, but this ratio is dimensionless and so has no units. Think of it this way: since the limit of hearing and threshold of hearing are both expressed as W/m^{2}, the ratio of these units cancel, resulting in a dimensionless ratio. 
p. 123 
Units for average pressure variation incorrect. 
Midpage, in the paragraph beginning “Using standard values...”, the expression at the end of that paragraph should be 
p. 139 Figure 5.10 
Extraneous “1” near origin 
An extraneous character “1” appears just to the left of the axis origin. 
p. 152 
Typo (terms are switched) 
First sentence on page reads in part: “... known as the hammer (incus), the anvil (malleus) ...” but should read, “ … known as the hammer (malleus), the anvil (incus) ...” 
p. 174 Figure 6.14 caption text 
Citation for Roederer is incorrect. 
Text should read, “Adapted from Roederer 1973.” 
p. 177 Fig. 6.16 
Typo 
Vertical axis says “phons”, but should say “phon”. 
p. 181 Table 6.1 
Incorrect bandwidth for Bark #13 
The Critical Bandwidth for Bark #13 should be ~ 320 Hz, not 100 Hz. 
p. 203 
Incorrect word 
The penultimate paragraph reads “whether we hold pressure or velocity constant”. It should read “whether we hold pressure or volume constant”. 
p. 181 Fig. 6.19 
Incorrect Q for band 15 
Critical Band #15 sticks out like a long pole in a tent. It should be ~ 6.44 (because 2900/450 = ~6.44). 
p. 287 Fig. 9.3 
Fig. 9.3 does not show the original “Ut queant laxis...” chant melody. The original chant melody is as shown.* 

p. 346, second line 
Typo 
"corresponding surpisal" should be "corresponding surprisal" 
p. 373, first sentence of the second bulleted paragraph 
Typo 
"themeslves" should be "themselves" 
p. 377 first ¶ after §9.22.2 
Incorrect citation 
Midparagraph, the text reads “In the network shown in figure 43b”, but should read, “In the network shown in figure 9.42b”. 
p. 398 fifth ¶ after §9.23.2 
Incorrect formula 
“M_{0}(PianoImprov) = (2 · A4) + (3 · B4) + (2 · G4)” should read: “M_{0}(PianoImprov) = (2 · C4) + (3 · E4) + (2 · G4)” 
p. 401, last line 
Typo 
"truely" should be "truly" 
p. 403 
Misspelled word: “ answsers”. Text should read: 
EMI’s analysis database is essentially a compendium of answers to the question, What would Mozart have done in this situation? 
Musimathics Volume 1 Errata – First Printing 

Location 
Problem 
Correction 
p. 5 
Incorrect statement 
The sentence leading from the bottom of page 4 to page 5 is incorrect. It reads, “The spring begins to go slack as the mass rises, and when the mass reaches the equilibrium point, the spring no longer lifts the mass upward.” It should read instead, “The spring begins to go slack as the mass rises, and when the mass reaches the equilibrium point, the force due to gravity is greater than that of the spring.” 
p. 14, last line 
Sentence should read as corrected. 
“Real numbers include all integers and all possible fractional and irrational values.” 
p. 20 
Correction 
Text reads, “The Lochrian mode is purely a theoretical mode, considered unusable by conventional music theory because of the tritone that exists between its final (7) and its fourth degree.” Text should read, “The Lochrian mode is purely a theoretical mode, considered unusable by conventional music theory because of the tritone that exists between its final (I) and its fifth degree (V).” 
p.22 Fig 2.10.b 
Penultimate note in F major scale is E not E#. Remove “#” after E. 

p. 26 Table 2.3 
Whole note rest is incorrect 
The way I learned it in school, the wholenote rest “hat” is “off”, and the halfnote rest “hat” is “on”. Evidently, I need to go back to school on this one. The wholenote rest should look like this:

p.29, Fig 2.19 
The plus signs in the list “f + 2f + 3f + ...” are mathematically meaningless. Fig. 2.27 better represents partials. A simple fix is to replace “+” with “,”, as shown to the right, representing the overtone frequencies as a series of integer multiples of a fundamental frequency. Alternately, to express the waveform that results from the combination of these sine components, let p(x) = sin(2 pi x t) where t is time, and then write p(f) + p(2f) + p(3f) + .... 

p. 29 sec. 2.8.1 
Change heading. (Not really an erratum, but it needs a better title.) Heading reads: “Partials, Fundamentals, and Overtones” 
Change to read “Fundamental, Partials, Harmonics, and Overtones” 
p. 42 just before Sec. 3.2.2 
Arguments to function f are reversed. The function is defined on page 41 bottom as f(k,v), but the examples of use on page 42 reverse the arguments: f(v,k). For example, the text reads, “A0 = f(0,9)” but should read “A0 = f(9,0)”. 
Here are the function arguments as shown in the text:
Here are the corrected function arguments:

p. 43 
Incorrect statement 
Text reads: “We can use equation (3.1) to add and subtract intervals. If x = 2 in that equation, then frequency f_{x} will be two octaves above frequency f_{R}.” Text should read: “We can use equation (3.3) to add and subtract intervals. If v = 2 in that equation, then frequency f_{k,v} will be two octaves above frequency f_{R}.” 
p.43, Fig. 3.1 
Plus signs are mathematically wrong, similar to the error on p. 29, Fig 2.19. The simplest fix is to remove the “+” signs. Alternately, the waveform can be expressed as a sum of sine components using the function p(x) as described above. 




p. 45 top Figures 3.2, 3.3, also p. 49 at the bottom figure 3.5 at the bottom 
The ratio for C is given as 1/2. 
The ratio for lowest pitch C should be 1/1, so that the octave above (2/1) would be correct. 
p. 46 first full paragraph 
Correction 
Text reads, “So the tempered fifth is almost 2 cents flat of a perfect fifth.” Text should read, “So the tempered fifth is almost 2 cents flat of a just fifth.” 
p. 48 bottom, 7th sentence up from the bottom starting with "2. The fifth is found by taking....." 
Ratio is shown as 12:9 
Ratio should be 9:6. 
p. 104 Equation (4.12) and (4.13) Average Acceleration 
Formulas (4.12) and (4.13) and their discussion are incorrect and misleading. 
Please replace the entire section “4.10 Acceleration” with this PDF file. 
p. 111 
Section 4.14.1 presents a wrong and a misleading derivation of kinetic energy. Equation (4.28) is missing a factor of 1/2. 
Please replace the entire section “4.14.1 Kinetic Energy” with this PDF file. 
p. 111 last line 
Misspelling 
“posses” should be spelled “possess”. 
p. 119 
Improvement 
Text reads: “Let P be the power of a wave at distance r_{1} propagating along direction V. This means that an amount of energy P is flowing through surface a_{1} each second. If no energy is lost, then the same power will flow through a_{2} each second as well, and P/a_{1} = P/a_{2}. Since the areas of surfaces a_{1} and a_{2} are proportional to the squares of their distances from the source S, the intensity I varies inversely as the square of the distance to the source...” Substitute: “Let P be the power of a wave at distance r_{1} propagating along direction V. This means that an amount of energy P is flowing through surface a_{1} each second. If no energy is lost, then the same power will flow through a_{2} each second as well, so total power P at a_{1} would be the same as at a_{2}. However, since the areas of surfaces a_{1} and a_{2} are proportional to the squares of their distances from the source S, the intensity I varies inversely as the square of the distance to the source...” 
p. 119, Equation (4.36) 
Incorrect equation 

p. 132 Equation (5.8) 
Angular Acceleration Equation (5.8) is incorrect and misleading, similar to problem on p. 104. Equation (5.8) should read as corrected. 

p.134, bottom, in bolditalic text: 
Improvement in wording to clarify concept. 
Should read, “Circular motion is the result of a centripetal force applied at right angles to the instantaneous velocity.” 
p. 139 Figure 5.10 
Extraneous character 
An extraneous character “1” appears just to the left of the axis origin. It should be removed. 
p. 143, sec. 5.5 
2^{nd} para. 1^{st} sentence: remove ref. to E_k. Also, E_k=mv^2 is missing a factor of 1/2 Sentence and equation should read as corrected. 

p.144 
Equation (5.27) and the sentence enclosing it are missing a factor of 1/2. Sentence and equation should read as corrected. 

p. 152 
Typo (terms are switched) 
First sentence on page reads in part: “... known as the hammer (incus), the anvil (malleus) ...” but should read, “ … known as the hammer (malleus), the anvil (incus) ...” 
p. 174 Figure 6.14 caption text 
Citation for Roederer is incorrect. 
Text should read, “Adapted from Roederer 1973.” 
p. 181 Table 6.1 
Incorrect values for Bark #0 Lower Band Edge and Critical Bandwidth 
Per [Zwicker 1961]: Bark 0 should be 0Hz for Lower Band Edge, 100Hz for Critical Bandwidth. 
p. 181 Table 6.1 
Incorrect bandwidth for Bark #13 
The Critical Bandwidth for Bark #13 should be ~ 320 Hz, not 100 Hz. 
p. 181 Fig. 6.19 
Incorrect Q for band 15 
Critical Band #15 sticks out like a long pole in a tent. It should be ~ 6.44 (because 2900/450 = ~6.44). 
p.193 – 194, Section 6.13.5 
Text incorrectly implies that if a speaker has intensity I, then at twice the distance the intensity is sqrt(I), whereas in fact it will be I/4. This mistake affects each equation on this page: sqrt should be replaced by a factor 1/4, and squaring by a factor of 4. 
Please replace the entire section “6.13.5 Distance Cues” with this PDF file. 
p. 203 
Incorrect word 
The penultimate paragraph it reads “whether we hold pressure or velocity constant”. It should read “whether we hold pressure or volume constant”. 
p. 204 paragraph immediately below Eq. (7.5) 
Text states “To determine the speed of sound we must determine the mass density of air...” However, I just gave the mass density of air in the previous sentence! What we really need is the average molecular mass of air. 
“To determine the speed of sound, we must determine the average molecular mass of air...” 
p. 210 sec. 7.8 2^{nd} para. 4^{th} sentence 
Incorrect spelling. 
“lightening” should be “lightning” 
p. 226 Figure 7.24 
The arrow labeled “Wavelength increases” should point up, not down. 

p. 232 Equation 7.26 
Formula for Doppler Shift in Two Dimensions is incorrect. The term u appearing inside the parentheses in the denominator should be outside the parentheses, as shown here. I have created a Mathematica notebook that explains this equation better which is available here. A free player of Mathematica notebooks can be downloaded here. For a vector formulation of Doppler shift, see http://ccrma.stanford.edu/~jos/pasp/Doppler_Effect.html 

p. 246 midpage (5th paragraph) 
Incorrect formula V = 7.5^ –4 m^3, should be V = 7.5 x 10^ –4 m^3. 

p. 257 Fig. 8.13 
Figure subheadings are incorrect. Should read as corrected. 
a) Fundamental (first harmonic) b) Second harmonic c) Third harmonic 
p. 260 sentence before runin heading “Bar with Free Ends” 
Sentence reads, “Plugging these values into (8.18) for n = 1,2,3,4,5 yields a fundamental and partials shown in the last column of table 8.3.” 
Sentence should read, “Plugging these values into (8.18) yields a fundamental and partials shown in the last column of table 8.3.” Delete “for n = 1,2,3,4,5”, there is no n in eq. 8.18. 
p. 346, second line 
Typo 
"corresponding surpisal" should be "corresponding surprisal" 
p. 373, first sentence of the second bulleted paragraph 
Typo 
"themeslves" should be "themselves" 
p. 401, last line 
Typo 
"truely" should be "truly" 
p. 359 Third sentence into section 9.17.5 
It would be better to say that Voss & Clark used a Gaussian noise generator than a uniform noise generator. 
Text reads: “To test this hypothesis, they synthesized melodies of three types using a computer: the first type made tone and rhythmic selections with a uniform...” But should read: “To test this hypothesis, they synthesized melodies of three types using a computer: the first type made tone and rhythmic selections with a Gaussian...” 
p. 396 
Description of the Fusion Petri net structure is misleading. The text reads, “Only one of the two input places can trigger M1,” however this does not agree with the structure of the diagram to the right of that paragraph, nor with the definition of the Petri net firing rule given on page 391. The text should read as corrected. 
Both of the two input places are needed to trigger M1. 
p. 403 
Misspelled word: “answsers”. Text should read: 
EMI’s analysis database is essentially a compendium of answers to the question, What would Mozart have done in this situation? 
p. 460 
End Note 4 in “Chapter 5” last sentence states incorrectly, “Instead, circular motion is the vector sum of centripetal force and linear velocity.” 
Corrected text should read: “Circular motion is the result of a centripetal force applied at right angles to the instantaneous velocity.” 
Musimathics Volume 2 Errata First Printing(Volume 2 has not had a second printing yet.) 

Location 
Problem 
Correction 

p. 30 sentence before Fig. 1.24 
Incorrect units 
Text reads: “In this example, values of x in the range –1/4 to nearly 1/4 map to the reproduction level value of 0.” Text should read: “In this example, values of x in the range –1/8 to nearly 1/8 map to the reproduction level value of 0.” 

p. 65 Eq. (2.31) 
The last term in the expression reads: \frac{7^{7}}{7!} but should read: \frac{z^{7}}{7!} Please substitute the equation to the right. 


p. 77 the sentence just before §2.6.8 
Textual improvement. 
Text reads: "We can see by inspection for sine and cosine that adding Pi to any angle is the same as negating it." Text should read: "We can see by inspection for sine and cosine that adding Pi to any angle is the same as negating the amplitude of the waveform at that angle." 

p. 79 
Bold printed remarks are incorrect. 
First ¶ text reads: A real cosine consists of the vector sum of two halfamplitude phasors of opposite frequency. Text should read: A real cosine consists of the vector sum of two halfamplitude phasors in conjugate symmetry. Last ¶ text reads: A real sine consists of the vector difference of two halfamplitude phasors of opposite frequency. Text should read: A real sine consists of the vector difference of two halfamplitude phasors in conjugate symmetry. 

p. 79, Eq. (2.53) 
Two problems: 1) the equation shows the sum of two phasors on the left side, but should show the difference. 2) Misuse of parenthesis on the right side. 
Corrected equation 2.53:


p. 83, Section 2.6.12 
Incorrect example and incorrect definition of odd function in nexttolast paragraph. 
Text reads, “For any x, the positive and negative functions are equal, and sin x = –sin x. Because of this, the sine function is an odd function. In general, a function f is odd if f(x) = –f(x).” Text should read, “For any x, the positive and negative functions are equal, and sin –x = –sin x. Because of this, the sine function is an odd function. In general, a function f is odd if f(–x) = –f(x)”. 

p. 84, Figure 2.25 and Table 2.3 
Text continues to assert that for odd functions, f(x) = –f(x), but again, this is incorrect. The correct definition of an odd function is one in which f(–x) = –f(x). 


p. 89 
Incorrect unit of measure. 
In the final sentence of the page, f_{2} is given in millihertz (mHz); it should be in megahertz (MHz). 

p. 96 
Bullet points near bottom of page are incorrect. 
Bulleted text reads, “Rotate the positivefrequency components of x(t) counterclockwise 90° by multiplying them by i. Rotate the negativefrequency components clockwise 90° by multiplying them by –i.” Text should read (for clarity, I've underlined the text that must change): “Rotate the positivefrequency components of x(t) clockwise 90° by multiplying them by –i. Rotate the negativefrequency components counterclockwise 90° by multiplying them by i.” 

p. 101 
Incorrect text in 3^{rd} paragraph. 
By investigating conjugate symmetrical phasors, we found that a real cosine is made up of the vector sum of two halfamplitude phasors of conjugate symmetry. Similarly, a real sine is made up of the vector difference of two imaginary halfamplitude phasors of conjugate symmetry. 

p. 105 first ¶ 
Typo 
For “clarinetlike”, please substitute “clarinetlike”. 

p. 106 Last line of section 3.1.6 
Wording improvement 
For “spectrogram”, please substitute “spectrum”. 

p. 109 2^{nd} ¶, bolditalic text 
Wording improvement 
Text reads, “If the product signal is all positive, then the signals being multiplied must be identical. If the product signal is mixed positive and negative, then the signals being multiplied are not identical.” Replace with: “The more positive the product signal is, the closer to identical are the source signals. The more mixed positive and negative the product signal is, the less identical are the source signals.” By “identical”, I mean that the source signals are exactly the same at every point, and do not differ in any property. This means, for example, there is no phase difference between the signals, no difference in DC offset, no amplitude difference, no timeshift difference, no difference in shape. For example, if some x(t) and y(t) signals are uncorrelated, their product will be mixed positive and negative. But if x(t) and y(t) are the same point for point, their product will be all positive (or 0) at every point. 

p. 133 first bullet point in 3.3.8 
Clarification 
Text reads, “Spectra of negative frequencies and positive frequencies of real signals are mirror images.” Please substitute, “Magnitudes of the spectra of negative frequencies and positive frequencies of real signals are mirror images.” 

p. 134 
Incorrect acronym 
The inverse discrete Fourier transform is at one point incorrectly given as IFDT; it should be IDFT. 

p. 135 Matrix figure in Section 3.4.1 
Top and bottom rows are correct. Middle rows show the superscript k+1 in the second column instead of k. Please substitute the corrected matrix figure to the right. 


p. 136, Section 3.4.3, second paragraph 
Incorrect assertions 
Text reads, “The imaginary part of x(n) will be zero if the imaginary part of X(k) was zero.” This is incorrect; x(n) will be real if the real part of X(k) is even and the imaginary part is odd relative to frequency 0. Substitute the following text: “The imaginary part of x(n) will be zero if the real part of X(k) was even and the imaginary part was odd relative to frequency 0.” 

p. 136 Section 3.4.4 first paragraph 
Unclear statement 
Text reads, “If the spectrum being processed by the IDFT came from a complex signal, the output of the IDFT may have a significant nonzero imaginary part. But we can still separate the real and imaginary output data in a meaningful way.” While not really an error, this is unclear, and not really what I wanted to say. What I meant to say follows below. Substitute the following text, “Even if the output of the IDFT has a significant nonzero imaginary part, we can still meaningfully separate the real and imaginary output data.” 

p. 137, last parenthetical sentence on page 
Incorrect assertion. 
Text reads, “(If the imaginary part of the input spectrum X(k) is zero, computing the imaginary part can be skipped.)” This is incorrect: The imaginary part being zero is not sufficient. The real part must also be even. Substitute the following text: “(If the imaginary part of the input spectrum X(k) is zero and the real part is even, then computing the imaginary part can be skipped.)” 

p. 140 § 3.5.1, 2^{nd} ¶ 
Typo 
Text reads: “... increasing the sampling rate R and/or the fundamental analysis frequency N until ...” Substitute the following text: “... increasing the sampling rate R and/or the fundamental analysis frequency f_{N} until ...” 

p.146 Eq. 3.36 
Incorrect index for odd function of x. 
The index for the odd part should be 2n+1, not 2n–1. Please substitute the following formula for Eq. 3.36.


p. 147 unnumbered equation at top of page. 
Incorrect index for odd function of x. 
As with the error on page 146, the index for the odd part should be 2n+1, not 2n–1. Probably a copy/paste error. Please substitute the following formula.


p. 155 1^{st} ¶ 
Incomplete thought 
Text reads, “The Hilbert transform of a signal is another signal whose frequency components are all phase shifted by 90º (–π/2 radians).” Substitute the following text: “The Hilbert transform of a signal is another signal whose frequency components are all phase shifted by 90º (–π/2 radians for positive frequencies, π/2 for negative frequencies).” 

p. 156 Item 3 
Typo 
Text reads: “Form the elementwise product of X(k) and h(t):” Should be: “Form the elementwise product of X(k) and h(k):” 

p. 163 add sentences to end of 2^{nd} ¶ 
Improvement 
This is not technically an erratum, but some readers have tripped over this point. Please append the following additional explanation to the end of the second paragraph that now ends with the sentence, “This rule even works even when N_{j} ≠ N_{g}”: “Recalling that we’ve defined as zero any values that lie outside the range of functions f and g, note that we will get the same result if we set the limit of summation in equation (4.1) to N_{f} + N_{g} – 1 or to any larger value, even to infinity.” 

p. 164 (§4.8) and p 165 (§4.9) 
The convolution sequence is incorrect. Row 1 is OK but rows 2 through 5 should have a leading zero and delete the trailing zero. The summation line has 5+5 elements and should only have 5+51 elements. Delete the trailing zero. 


p. 168, first equation after section heading 4.4.2. 
Font for F(k) on right side of equation is incorrect, should be standard italic font face. 


p. 171 Figure 4.13 
Some values of sampled functions f(n) and g(n) and their product function are incorrect. The graphical functions in this figure are correct, including the spectral plot. 
There are really two problems here. First, there are transcription errors in the sampled functions f(n) and g(n). More fundamentally, however, the figure implies that the graphical functions can be reproduced from the sampled functions, which is not true, given how highly truncated the sample values are. Basically, this figure and accompanying text do not provide enough information to adequately demonstrate what is being discussed. The reader interested in a fuller understanding of the steps shown in this figure and corrected sampled functions are referred to this PDF file. If you prefer, here is the Mathematica notebook. A free Mathematica player for this notebook is available for download here. 

p. 172 4^{th} line 
Text is in the wrong section 
Text reads, “Multiplying in the frequency domain convolves in the time domain.” True, but this ended up in the wrong section. (A following section talks about multiplying in the frequency domain). Substitute “Convolving in the frequency domain multiplies signals in the time domain.” 

p. 173 
Text immediately above Eq. 4.15 and that equation, should both refer to the inverse Fourier transform. 
Using the notation F ^{–}^{1}{ } for the inverse Fourier transform, we can express this operation as


p. 181 
Add text to end of first paragraph after Eq. 4.19 
“(For simplicity, this analysis ignores possible scaling asymmetries that may arise, depending precisely upon which Fourier transform is utilized.)” 

p. 183 first sentence 
Improvement 
“It is a basic premise of physics that periodicity and frequency are ...” Substitute: “It is a basic premise of physics that period and frequency are ...” 

p. 183 Equation 4.21 
Typo 
Text reads: “f(t)” Substitute: “f” 

p. 191 Figure 4.36 title 
Typo 
Figure 4.36 title reads: “Sinc squared function and its triangular spectrum.” Substitute: “Sinc squared function and its triangular waveform.” 

p. 203 last sentence 
Incorrect description 
Text reads: “The components between the test signals are the result of phase delays introduced by the filter.” Substitute: “The components between the test frequencies are the result of artifacts of the analysis method (windowing of the transform with a nonharmonic test signal).” 

p. 215 unnumbered display equation just after Equation (5.31) 
The term  pi T, should be pi over 4 T. 


p. 215 Figure 5.14 
The Radians vertical axis should read from top to bottom 0, pi over 4, pi over 2. 


P 216 Equation (5.32) Real Frequency Response 
The coefficient t should be T. 


p. 227 first line 
Typo 
Text says “ω=2π/96”, but should say “w=2π/16”. 

p. 227 Figure 5.18 b. 
Figure 5.18 b should show a spiral shrinking counterclockwise. 


p. 227 Figure 5.18 c. 
Figure 5.18 c should show a spiral expanding counterclockwise. 


p. 227 table just before section 5.11.2. 
z^n < 1 Description is incorrect, should be clockwise. z^n > 1 Description is incorrect, should be clockwise. 
z^n < 1 Contracting clockwise circle z^n > 1 Expanding clockwise circle 

p. 228 1^{st} paragraph, section 5.11.3 
Reference to figures 5.18a and 5.18b should instead reference 5.18b and 5.18c, respectively. 
Text should read: “If we sum the sequence shown in figure 5.18b, ...” “On the other hand, the sum of the sequence in figure 5.18c diverges, ...” 

p. 229 text following Equation 5.53 
The range of n is misstated. 
The range of n is misstated in the text following equation (5.53). The offending sentence reads in part: “For n = 0, 1, 2, …, the sum of all previous terms ...” but it should read “For n = 1, 2, 3, …, the sum of all previous terms ...”. 

p. 234, about 2/3^{rd} of the way down the page 
Extra term in inline expression. 
Text reads, “By the shift theorem of the Z transform, we can rewrite this term as Y(z) = z^{–m}Y(z).” Text should read, “By the shift theorem of the Z transform, we can rewrite the shaded term as z^{–m}Y(z).” 

p. 238 paragraph before Eq. 5.71. 
Incorrect definition of z. The exponent of e should be positive. 
The sentence reads: “Now consider what happens when we take equation (5.70), which represents the factored form of H, and set e^{–}^{iwT}...” (note the minus sign in the exponent) Text should read: “Now consider what happens when we take equation (5.70), which represents the factored form of H, and set e^{iwT}...” (note the minus sign no longer in the exponent) 

p. 239 paragraph above equation (5.72) 
Incorrect assertion about e to imaginary powers. 
Text reads: “and e^{anything} = 1”. It should add i to the exponent. Text should read: “and e^{i }^{anything} = 1” 

p. 240 3^{rd} line 
Incorrect formula 
Formula reads: “e^{i}^{ω}^{T} – Q_{1} ” Text should read: “e^{i}^{ω}^{T} – Q_{n} ” 

p. 241, 2^{nd} line. 
Definition of Θ(ω) function is incorrect, misplaced parenthesis. 
Text reads: “... we can define Θ(ω) = ∠H(e) ^{–}^{i}^{ }^{ωT}.” Text should read: “... we can define Θ(ω) = ∠H(e ^{i}^{ }^{ωT}).” Note the changed location of parentheses and the removed minus sign. 

p. 241 text in bolditalic. 
Missing a phrase. 
Text reads: “... minus the sum of the angles of the vectors to the point e ^{i}^{ }^{ωT}.” Should be: “... minus the sum of the angles of the vectors from the poles to the point e ^{i}^{ }^{ωT}.” 

p. 246 text above equation (5.82) 
Incorrect definition. 
Text reads: “... we know we can say H(e^{–}^{iw}) = a_{0} + a_{1} e^{–}^{iw}.” (note the minus sign in the exponent) Text should read: “... we know we can say H(e^{iw}) = a_{0} + a_{1} e^{–}^{iw}.” (note removed minus sign in the exponent) 

p. 248 Fig. 5.27 and Fig. 4.28 
Incorrect z axis values. 
The z axis range of Figs. 5.27 and 5.28 should be 0 – 2, not 0 – 1, as shown, to agree with Eq. 5.83 and Figs. 5.25 and 5.26. 

p. 258, first paragraph following the equations, last sentence 
Improvement 
Text reads: “So we see that the behavior of the filter when the poles are on the real axis is identical to the onepole filter.” Substitute: “So we see that when the poles are on the real axis, this filter behaves similarly to the onepole filter.” 

p. 258 3^{rd} from last ¶ 
Simplify, remove extraneous concepts 
Text reads: “Scaling power by ½ is the same as attenuating power by –3 dB SIL or by –6 dB SPL.” Substitute: “Scaling power by ½ is the same as attenuating amplitude by approximately –3 dB.” 

p. 262 next to last paragraph, last sentence 
Missing a phrase (like on page 241) 
Text reads: “... minus the sum of the angles of the vectors to the same point.” Should be: “... minus the sum of the angles of the vectors from the poles to the same point.” 

p. 272 Fig. 6.8 
Incorrect title text 
Text reads: “Plot of e.” Substitute: “Plot of e^{x}.” 

p. 274 just before Eq. 6.15 
Typo 
Text reads: “... then the second derivative of the sine is the negated cosine.” Should read: “... then the second derivative of the cosine is the negated cosine.” 

p. 275, sentence after equation 6.20 
Incomplete formula 
Text reads: “Thus the acceleration of the air packet is –a^{2}.” Substitute: “Thus the acceleration of the air packet is –a^{2} sin aθ.” 

p. 290 
Incorrect term in equations 
In Section 6.3.3, Driven Harmonic Oscillator, equations 6.53, 6.54, and 6.56 show term cy''(t), but should show cy'(t). Correct as follows:


p. 295 after Eq. 6.63 
Add sentence for clarity immediately after Eq. 6.63. 
(Though I've dropped the square root from the definition of δ(ω), the derivative of the positive root is still valid.) 

p. 305 § 7.1.4 
Incorrect terms in equations 7.16 and following 
Equation (7.16) the 2^{nd} function call in numerator: “f(x1 + t1)” should be “f(x1,t1)”, and the limit “as x approaches infinity” (x>inf) should be “as delta x approaches zero” (delta x>0) Unnumbered equation directly under (7.16): limit “as t approaches infinity” (t>inf) should be “as delta t approaches zero” (delta t>0) 

p. 311 
Incorrect count for matrix 
Text reads: “... we end up with an N × M matrix ...” Substitute: “... we end up with an N +1 × M+1 matrix ...” 

p. 353 second from last line 
Typo 
Text reads: “... from the battery...” Substitute: “... from the oscillator...” 

p. 356 Figure 8.26 
Fontosis 
The music fonts in the two staves at the top right of the figure are incorrect. The correct figure is shown here.


p. 368 Eq. 9.2 
Improvement 
Qualify the valid range of t on the second line of Eq. 9.2 as a ≤ t ≤ a+d. 

p. 369 Figure 9.7 
Typo: x axis maximum is incorrect 
In Figure 9.7, the point at which the waveform goes to zero should be 0.7, not 1. Here is just the corrected part.


p. 374 
Midpage, for k = 0 the table incorrectly gives frequency as DC. Correct frequency for k = 0 is 1. 
Text should read (only first 4 columns shown here):


p. 375 
Bottom of the page, for k = 0 the table incorrectly gives frequency as DC. Correct frequency for k = 0 is 1. 
Text should read (only first 4 columns shown here):


p. 376 Eq. 9.12 
Improvement 
The equation shown for the nonbandlimited triangular wave, while correct, does not have the same phase as Eq. 9.11, the bandlimited triangular wave. This formula provides the same phase as Eq. 9.11: f(t) = 2  t – π  / π – 1, but it is limited in range to 0 ≤ t ≤ 2π. To remove these limitations, if desired, we can replace Eq. 9.12 with the following: f(t) = 2  2 t /(2π) – 1  – 1 where ... is the floor function. 

p. 380 
Incorrect formula for linear interpolation. Two errors. 
Last full paragraph, text reads, “the interpolated result would be y = 0.7 y_{14} + (1 – 0.7) y_{15 }= 4.11”, but text should read, “the interpolated result would be y = 0.7 y_{15} + (1 – 0.7) y_{14 }= 4.11”. Just below this the text reads “Step 2: y = σy_{⎣}_{s}_{⎦ }+ 1 – σy_{⎣}_{s+1}_{⎦}”, but text should read “Step 2: y = σy_{⎣}_{s+1}_{⎦} + (1 – σ)y_{⎣}_{s}_{⎦}”. 

p. 381 
Questionable assertion 
Text says, “Spectrally, linear interpolation is equivalent to a secondorder lowpass filter with a triangular impulse response.” Substitute: “Spectrally, linear interpolation is similar to a secondorder lowpass filter with a triangular impulse response.” 

p. 390 Fig. 9.29a 
Bounding arrows too small to see. 
The negativefrequency spectrum of Fig. 9.29a shows two tiny bumps to the left and right above –1000 Hz. These are actually the heads of a doubleheaded arrow that is showing the extent of the modulating frequency f_{m} , but they are too small to distinguish on the printed page. The figure fragment shown here corrects this appearance by replacing the doubleheaded arrows with two singleheaded arrows bracketing the modulating frequency f_{m}.


p. 416 Eq. 9.47 
Extraneous term in matrix formulation. 


p. 421 Section 9.5.3 
Incorrect term in equation 9.49 
In the second piecewise equation, “1–cos(beta*t)”, should be “1–cos(beta*n)”. 

p. 422 
Incorrect subscript in figure 9.52 
Subscripts on parameters for the 2^{nd} patch bank should be subscripted “2” in order to show a progression to “N” in the bottom row of the patch. 

p. 440 Fig. 9.71 
Incorrect subscript in equation in figure 9.71 
The equation for R0,1 is missing term Z_{0.} The equation should be written as (Z_{1}Z_{0})/(Z_{1}+Z_{0}), as shown here.


p. 441 § 9.7.3 2^{nd} ¶ 
Offbyone error 
In 2^{nd} paragraph: “If we sample these traveling wave components at N equidistant points ...” Should read: “If we sample these traveling wave components at N+1 equidistant points ...” In 3^{rd} paragraph: “...other end the nut termination at position x = N – 1” Should read: “...other end the nut termination at position x = N” since it's length N. 

p. 462 Fig. 10.10 
Upper “board” is timereversed. 
The figure doesn't show x(–1)h(1) as described. Flipping the top row about h(0) (timereversing) fixes it, as shown here.


p. 463 
Typo in 4^{th} line 
“analized” should be “analyzed”. 

p. 465 Fig. 10.13.a 
Incorrect spectrum in figure. 


p. 465 last 2 equations, p. 466 first equation 
Incorrect derivation 
The
last two equations on page 465 and first equation on 466 should
contain h(r), not h(–r) This makes things a little easier on page 466. We can delete the 2^{nd} paragraph, beginning “The negative index for h(–r)...” through and including the following equation that ends “if and only if h(r) = h(–r).” Also, in equation 10.11, we can delete the text “if and only if h(r) = h(–r).” 

p. 479 equation 10.18 
Improper substution. 
Equation 10.18 is supposed to be the same as equation 10.4 with the substitution n = sR. However, I got carried away and also substituted r = sR in the superscript of e. The superscript shown, –i2πk(sR)/N, is incorrect, and should be –i2πkr/N. The corrected formula is shown here:


p. 521 unlabeled display equation immediately before Equation (A.20) 
Parentheses are missing after the coefficient i. 

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