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`BEFORE THE PATENT TRIAL AND APPEAL BOARD
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`APPLE INC.,
`Petitioner,
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`v.
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`ANDREA ELECTRONICS INC.,
`Patent Owner.
`
`Patent No. 6,363,345
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`IPR2017-00626
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`REPLY DECLARATION OF BERTRAND HOCHWALD
`REGARDING U.S. PATENT NO. 6,363,345
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`
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. Cover
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`
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`TABLE OF CONTENTS
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`INTRODUCTION ......................................................................................... 1
`I.
`II. RESPONSE TO DR. DOUGLAS’S OPINIONS ........................................ 1
`A. Martin’s Sub-Windows Are an Optional Feature ................................. 1
`B. Martin Discloses the Claimed “Future Minimum” Even Where
`Sub-Windows Are Used ........................................................................ 5
`C.
`Well His Noise Floor Algorithm Works ............................................... 9
`D. Dr. Douglas Mischaracterizes My Deposition Testimony .................. 11
`E.
`Is a Long Time .................................................................................... 12
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`Dr. Douglas Is Incorrect that Hirsch Teaches That 0.2 Seconds
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`Dr. Douglas Misinterprets Martin’s Own Description of How
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. i
`
`
`
`I.
`
`INTRODUCTION
`I have been retained by counsel for Apple Inc. as an expert witness in
`1.
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`the above-captioned proceeding. I have been asked to provide an opinion
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`regarding the patentability of certain claims in U.S. Patent No. 6,363,345
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`(“the ’345 Patent”) (Exhibit 1001). I previously submitted declarations in this
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`matter as Exhibits 1003 and 1004.
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`2. My background and qualifications are set forth in my opening
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`declarations Exhibits 1003 and 1004. A copy of my CV was attached as Exhibit B
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`to those declarations. I disclosed the compensation I am receiving, and prior
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`testimony in my opening declarations. I also set forth my understanding of the
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`relevant legal standards in my opening declarations.
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`3.
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`I understand that Andrea submitted responses to the petitions and the
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`Institution decisions, and that Andrea submitted two declarations from Dr. Scott
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`Douglas (both labeled Ex. 2002). I have considered Andrea’s Responses and Dr.
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`Douglas’s declarations, and this declaration sets forth my reply to certain of
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`Andrea’s and Dr. Douglas’s arguments.
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`II. RESPONSE TO DR. DOUGLAS’S OPINIONS
`A. Martin’s Sub-Windows Are an Optional Feature
`Andrea and Dr. Douglas contend that multiple sub-windows (W > 1)
`4.
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`are a “crucial” part of Martin’s algorithm. [Ex. 2002 (-626 Douglas) at ¶60.] They
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`are wrong because sub-window(s) are not crucial for rapid adjustment of noise
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 1
`
`
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`level. Using W = 1 in Martin’s algorithm is a perfectly reasonable choice for that
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`parameter.
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`5. Martin says the overall window length L must be large enough to
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`bridge any peak of speech activity, but short enough to follow non-stationary noise
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`variations. He does not make similar comments about the number of sub-windows
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`W. [Ex. 1006 at 1094.] Martin does not specify any upper or lower bounds on W.
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`Where W = 1, the length of each sub-window M is equal to the length of the
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`window L. Martin does not suggest that these values would not work. On the
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`contrary, he specifies these values as configurable parameters which one in the art
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`would understand how to set. One in the art would understand that Martin’s
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`algorithm functions equally well for any positive integer W. [Ex. 1006, Figure 2.]
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`6. Martin says a window time length of 0.625 (seconds) is “a good
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`value”, and this value corresponds in his example to window sample length of L =
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`5000. He does not provide any qualitative assessment of how many sub-
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`window(s) W would be “good.”
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`7. Martin explains that W is chosen at least in part on the basis of
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`“computational complexity and delay” [Ex. 1006 at 1094.] The basis for
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`“computational complexity” used by Martin at time of publication was in 1993.
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`Six years later in 1999, at the time of the filing of the ’345 patent, computers were
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`considerably faster and more capable. Hence a value of W that would be chosen in
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 2
`
`
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`1993 could differ in 1999 or today. Martin had the foresight to anticipate this
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`issue, and allow the choice of W to be a design variable, whether smaller or larger.
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`8. Martin says sub-windows can “improve[e] the noise tracking
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`capability” for “a rapid noise power increase.” [Ex. 1006 at 1094.] Martin does
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`not state that this feature is required to track noise. Just that it improves noise
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`tracking in some circumstances.
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`9.
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`According to Martin’s algorithm, the noise floor Pn(i) adjusts to rapid
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`noise power decreases, because the noise floor is immediately updated if the
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`current smoothed power is less than the floor. This is true for any W.
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`10. Other aspects of Martin’s algorithm are not affected by the choice of
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`W. For example, the noise floor Pn(i) is never allowed to be above 𝑃𝑃�x(i). [Ex.
`1006 at Figure 2.], and 𝑃𝑃�x(i) has no dependency on W.
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`11. Dr. Douglas asserts that Martin does not update the noise floor Pn(i)
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`periodically. [Ex. 2002 (-626 Douglas) at ¶72.] That statement is not correct.
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`Where W = 1, Martin’s noise floor Pn (i) is always set to PMmin at the end of the
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`window. In Martin’s Figure 2, both branches of the monotonically increasing test
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`simplify to the same result when W = 1. In the “no” branch, Martin selects the
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`minimum of the last W values stored in min_vec (italicized for ease of reading).
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`Martin shows this through the mathematical statement min(min_vec(r*M),
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`min_vec((r-1)*M),… min_vec(r-W+1)*M). The last value in this list is min_vec(r-
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 3
`
`
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`W+1)*M, which is equal to min_vec(r-1+1)*M because W = 1, which then
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`simplifies to min_vec(r*M). Therefore Martin selects min(min_vec(r*M),
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`min_vec(r*M)), which simplifies to min_vec(r*M). Martin sets min_vec(r*M) =
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`PMmin, and therefore, the “no” branch simplifies to
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`Pn(i) = min(min_vec(r*M)) = min(PMmin) = PMmin.
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`Because the sub-window and the window are the same length, the minimum of
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`each sub-window is also the minimum of the window.
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`12. Dr. Douglas asserts that without the “monotonically increasing
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`power” block, the noise floor Pn(i) would never increase because “the algorithm
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`would only adjust the noise level downward.” [Ex. 2002 (-626 Douglas) at ¶97.]
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`But that is not correct. Martin explains that the noise floor would increase after
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`L+M samples, but where sub-windows are used, “this delay is reduced to M
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`samples.” [Ex. 1006 at p. 1094.] While the delay is shorter when sub-windows are
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`used, the noise floor can still increase without sub-windows. In any event, by
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`choosing W = 1, we may have Pn(i) increase at intervals of M samples.
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`13. Dr. Douglas’s assertion that the monotonically increasing block of
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`Martin is “crucial” is also inconsistent with Prof. Rainer Martin’s follow-on work.
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`In 1994, Prof. Martin published another article that describes use of his noise floor
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`algorithm in a spectral subtraction system. While Prof. Martin uses sub-windows
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`(where D is the window length, M is the sub-window length, and W is the number
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 4
`
`
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`of sub-windows, D = M * W), he does not include a monotonically increasing
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`determination in that algorithm. [Ex. 1031 (Martin 94) at p. 1183.] Prof. Martin
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`states that “In case of increasing noise power the update of noise estimates is
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`delayed by D + M samples.” [Ex. 1031 (Martin 94) at p. 1183.] This is the same
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`duration described in Martin 93 [Ex. 1006] for the non-monotonically increasing
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`block. If the monotonically increasing block of Martin 93 were truly a “crucial”
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`part of the algorithm, Prof. Martin would have included it in his 1994 algorithm.
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`Prof. Martin’s 1994 paper confirms that a person working in the field would have
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`viewed that block as an optional feature of the noise floor algorithm.
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`B. Martin Discloses the Claimed “Future Minimum” Even Where
`Sub-Windows Are Used
`14. Andrea and Dr. Douglas contend that where W = 4, Martin does not
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`disclose the current and future minima. [Ex. 2002 (-626 Douglas) at ¶¶64-71.]
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`They are wrong. Even where W = 4 Martin discloses those elements.
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`15. As noted in my earlier declaration [Ex. 1003, ¶¶136-39], when W = 1
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`we may map Martin’s Pn(i) to the ’345 “current minimum value” and Martin’s
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`PMmin to the ’345 “future minimum value”. This discloses the claimed current and
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`future minima.
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`16. When W = 4, we may keep this mapping the same. Martin stores each
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`PMmin value in the min_vec array, and then selects either the most recent or the
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 5
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`
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`smallest PMmin value from the past W values for assignment to Pn(i). [Ex. 1006,
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`1094.] This mapping can, in fact, be applied for any W, and does not contradict the
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`mapping I give in the paragraph above when W = 1 because
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`min(min_vec(r*M),…,min_vec((r-W+1)*M)) = PMmin when W = 1.
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`17. Dr. Douglas addresses the monotonically increasing and non-
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`monotonically increasing scenarios separately. I will do the same.
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`18. Dr. Douglas states that where the signal is monotonically increasing,
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`the noise floor Pn(i) is set equal to the PMmin value of the current sub-window
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`instead of to the smallest PMmin value across the data window L. [Ex. 2002 (-626
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`Douglas) at ¶66.] According to Dr. Douglas, this means PMmin cannot be the
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`“future minimum” because it is not the minimum of the data window L. But
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`nothing in the claim specifies a particular data window over which the “future
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`minimum” must be calculated. PMmin is, in fact, a minimum value. Specifically, it
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`is the minimum value within the sub-window, and that is sufficient to meet the
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`claim language.
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`19. Dr. Douglas states that where the signal is not monotonically
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`increasing, the noise floor Pn(i) is set to a value from min_vec and not to a PMmin
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`value. [Ex. 2002 (-626 Douglas) at ¶70.] Dr. Douglas mischaracterizes the Martin
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`algorithm. The min_vec variable stores the PMmin values. This can be seen in the
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`top box of the excerpt from Figure 2 of Martin (see Figure A on next page). At the
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 6
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`end of each sub-window of M samples, Martin stores the PMmin value in min_vec.
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`Hence, every value in min_vec represents a PMmin value from a sub-window.
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`Figure A
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`The left hand side of Figure A shows the non-monotonically increasing branch. In
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`this branch, Martin’s algorithm sets Pn(i) equal to the smallest PMmin value from the
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`past W sub-windows by selecting the smallest value out of min_vec. Martin’s use
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`of min_vec as intermediate storage of the PMmin values does not change the fact that
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`Pn(i) is set equal to the smallest PMmin value in the past W sub-windows.
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`20. Hence, whether the signal is monotonically increasing or not, Pn(i)
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`(current minimum) is set equal to a PMmin value (future minimum) at the end of
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`every sub-window.
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`
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 7
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`
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`In my first declaration I provided the annotated figure (excerpt reproduced above),
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`and explained that where W = 1, both boxes (which are in the bottom blue
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`rectangle) resulted in Pn(i) being set to PMmin. [Ex. 1003 at ¶140.] The same is also
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`true for W > 1 (e.g., W = 4). Either way, Pn(i) will be set to a PMmin value. If
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`monotonically increasing is determined in the decision diamond, Pn(i) is set to the
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 8
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`most recent PMmin. If not monotonically increasing, Pn(i) is set to the smallest of
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`the W past PMmin values.
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`C. Dr. Douglas Misinterprets Martin’s Own Description of How
`Well His Noise Floor Algorithm Works
`21. Andrea and Dr. Douglas contend that Martin said his algorithm is
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`“biased” and does not work well. [Ex. 2002 (-626 Douglas) at ¶87.]
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`22. They are wrong because: (i) Martin states his algorithm when used
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`with spectral subtraction reduces noise by 10 dB without creating musical tones,
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`which a person skilled in the art would have recognized is a non-trivial
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`improvement; and (ii) Martin uses the word “bias” to refer to the difference
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`between the noise floor and the average noise level, and there are ways to
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`compensate for this effect.
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`23. Martin explains [Ex. 1006 at p. 1096] that his algorithm was used with
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`a filter bank in a spectral subtraction experiment. He explains that “few annoying
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`musical tones” and “improvement of about 10 dB” were both observed. He also
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`explains [Ex. 1006 at p. 1095] “our SNR [signal-to-noise ratio] estimate shows
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`good agreement with the true SNR” and his algorithm was “successfully
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`incorporated in several speech processing systems.” Martin therefore gives ample
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`incentive for a reader to utilize and build upon his results.
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 9
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`24.
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`In particular, an improvement of 10 dB represents a factor of 10
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`improvement. Improving the signal-to-noise ratio by 10 dB is equivalent to
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`reducing the noise power by a factor of ten relative to the signal; this would be
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`recognized to a person skilled in the art as being very compelling and significant.
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`One in the art would have understood that noise suppression techniques involved
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`tradeoffs between noise suppression and the introduction of artifacts into the
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`cleaned signal. That Martin reports that his approach resulted in few annoying
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`tones would have been understood as a significant result showing that Martin’s
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`algorithm works well.
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`25. Martin explains [Ex. 1006 p. 1095] that “the estimate is biased when
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`no speech is present.” Martin explains that “the minimum power estimate is
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`smaller than the true noise power.” [Ex. 1006 p. 1094] By underestimating the
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`noise in the absence of speech, the algorithm tends to overestimate the signal-to-
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`noise ratio in the absence of speech [Ex. 1006 Figure 3]. (A smaller denominator
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`in the signal-to-noise ratio gives a larger signal-to-noise ratio.)
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`26. Bias is well known to a person skilled in the art as a form of
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`systematic offset where your estimate differs, on average, from the true value you
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`are estimating. It is also known to a person skilled in the art that if the bias is
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`known or can be estimated, then compensation factors can eliminate the bias.
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 10
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`27. Martin explains that one way to compensate for the bias is to use a
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`compensating overestimation factor “ofactor” [Ex. 1006 at p. 1094]. After use of
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`this factor, Martin explains that “the noise power estimate is approximately
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`unbiased” [Ex. 1006 at p. 1095]. Hence, the effect of the bias is mitigated and is of
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`little consequence in Martin.
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`28. Rather than teach away from Martin, Hirsch also uses adopts an
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`overestimation factor β in the range of 1.5 to 2.5 that plays a similar role as
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`“ofactor” in Martin to remove the bias in the noise estimate. A person skilled in
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`the art would therefore see similarities in the teachings of Hirsch and Martin and
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`would be motivated to consider the two together.
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`D. Dr. Douglas Mischaracterizes My Deposition Testimony
`29. Andrea and Dr. Douglas mischaracterize my deposition testimony
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`about the monotonically increasing block in Martin. [Ex. 2002 (-626 Douglas) at
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`¶¶94-103.]
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`30. As I explained during the deposition, a person skilled in the art would
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`have known there were multiple ways to implement a test to determine whether a
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`sequence of numbers is increasing. [Ex. 2005 at 69-71.] The details how one
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`would implement that test vary. Martin does not disclose the particular algorithm
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`he uses to test for monotonicity, but implementing such a feature was well within
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`the skill of one in the art. For example, this test could be performed digitally by
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 11
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`computer using a sequence of comparisons on min_vec, or a sequence of
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`comparisons on 𝑃𝑃�x(i).
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`31. As I explained at my deposition, the implementation details of this
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`determination are irrelevant to my opinions. See also [Ex. 2005 at pp. 80-85].
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`E. Dr. Douglas Is Incorrect that Hirsch Teaches That 0.2 Seconds Is
`a Long Time
`32. Dr. Douglas asserts that a person skilled in the art would have viewed
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`Martin’s 0.625 second period as a long time compared to Hirsch’s 0.4 second
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`period [-626 Douglas at ¶¶84-85]. He also states that a person skilled in the art
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`would be discouraged from using Martin due to Hirsch’s statement that most
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`known approaches require relatively long segments of past speech. He is incorrect.
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`33. Hirsch cites to several references that describe algorithms for
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`estimating noise. These include Martin [6], a prior article by Hirsch [7], and an
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`article by Campernolle [3]. [Ex. 1005 at 153.] In his own prior article, Hirsch
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`points out that a variety of windows 0.250, 0.5, 1.0, and 2.0 seconds [Ex. 1032 at p.
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`10] can be considered for estimating noise characteristics in speech. There is a
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`tradeoff between accuracy of estimating the statistical characteristics of the noise,
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`and the ability to adapt to the noise. The optimum choice of window depends on
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`the nature of the speech signals being considered. Hirsch concludes that “a length
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`of 500 ms [0.5 second] seems to be a good compromise for the cases we have
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 12
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`
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`examined” [Ex. 1032 at p. 24]. Hirsch acknowledges that there is no universal
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`value that is optimal for all cases.
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`34. Other known approaches to estimating noise operate on segments of
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`speech that are longer than 0.400 or 0.625 seconds. For example, Helf describes in
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`[Ex. 1010 at 8:19] that his effective window length is a 10 second interval over
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`which he performs a search for a minimum.
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`35. The Campernolle article describes a system where “histograms are
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`restarted every 10 secs of (presumed) speech” [Ex. 1033 at 14], and “effective time
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`constants of 20 to 50 seconds depending on the mixing ratio of speech and silence”
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`[Ex. 1033 at 15].
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`36. Hence, Martin’s window of 0.625 seconds is perfectly reasonable for
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`the cases considered by Martin and not significantly different from the 0.400
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`seconds used by Hirsch.
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`37. There is no universal agreement on what is the window length that
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`optimizes the tradeoff on accuracy of noise estimation and the ability to adapt.
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`Hirsch’s segment length of 0.400 seconds, and Martin’s window length of 0.625
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`seconds are both reasonable choices, depending on the situation. One does not
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`preclude the other, and one working in the field would have understood how to
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`combine the algorithms and select an appropriate time window.
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 13
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`* * *
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`I, Bertrand Hochwald, do hereby declare and state, that all statements made
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`herein of my own knowledge are true and that all statements made on information
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`and belief are believed to be true; and further that these statements were made with
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`the knowledge that willful false statements and the like so made are punishable by
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`fine or imprisonment, under Section 1001 of Title 18 of the United States Code.
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`
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`Executed on: February 7, 2018
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 14
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`
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`Exhibit List
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`I set forth the list of exhibits that I relied upon in forming my opinions in my
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`opening declarations Exhibits 1003 and 1004. In addition to those exhibits, I also
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`have considered the exhibits and documents listed below.
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`
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`1027
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`1028
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`1029
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`Exhibit # Reference Name
`
`Institution Decision
`
`Andrea’s Patent Owner Responses
`2002
`Dr. Douglas’s Declaration
`2005
`My Deposition Transcript, dated Oct. 12, 2017
`1026
`Transcript from Deposition of Scott Douglas dated Jan. 17,
`2018
`Exhibit 1 from Douglas Dep., Figure 27 depicting Current and
`Future Minima
`Exhibit 2 from Douglas Dep., Dr. Douglas’s mark up of Exhibit
`1
`Exhibit 8 from Douglas Dep., Declaration of Scott Douglas in
`Support of Complainant Andrea’s Claim Construction Brief in
`Inv. No. 337-TA-949 (Oct. 19, 2015)
`Transcript from Deposition of Scott Douglas dated June 16,
`2017, taken in Inv. No. 337-TA-1026
`Rainer Martin, Spectral Subtraction Based on Minimum
`Statistics, Proc. EUSIPCO-94, pp. 1182-85 (1994) (“Martin
`94”)
`H. G. Hirsch, “Estimation of Noise Spectrum and its
`Application to SNR Estimation and Speech Enhancement,”
`Technical Report TR-93-012, International Computer Science
`Institute (1993) (reference [7] in Martin 93)
`D. Van Campernolle, “Noise Adaptation in a Hidden Markov
`Model Speech Recognition System”, Computer Speech and
`
`1030
`
`1031
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`1032
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`1033
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`Reply Declaration of Dr. Bertrand Hochwald
`
`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 15
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`
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`Language, Vol. 3, pp. 151-167 (1989) (reference [3] in Martin
`93)
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`Reply Declaration of Dr. Bertrand Hochwald
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`IPR No. 2017-00626
`Apple Inc. v. Andrea Electronics Inc. - Ex. 1023, p. 16
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`