NOTE: This disposition is nonprecedential.

 

United States Court of Appeals 

for the Federal Circuit ______________________ 

ANDREA ELECTRONICS CORPORATION,

Appellant

v.

APPLE INC.,

Appellee

______________________ 

2021-1248

______________________ 

Appeal from the United States Patent and Trademark 

Office, Patent Trial and Appeal Board in No. IPR2017-

00626.

______________________ 

Decided: April 22, 2022

______________________ 

WILLIAM D. BELANGER, Troutman Pepper Hamilton 

Sanders LLP, Boston, MA, argued for appellant. Also represented by FRANK D. LIU; ANDREW PETER ZAPPIA, Rochester, NY. 

 JOSHUA JOHN FOUGERE, Sidley Austin LLP, Washington, DC, argued for appellee. Also represented by THOMAS 

ANTHONY BROUGHAN, III, JEFFREY PAUL KUSHAN; TIMOTHY 

Q. LI, New York, NY. 

 ______________________ 

Case: 21-1248 Document: 33 Page: 1 Filed: 04/22/2022
2 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

Before MOORE, Chief Judge, REYNA and CHEN, Circuit 

Judges.

CHEN, Circuit Judge. 

Patent owner Andrea Electronics Corp. (Andrea) appeals the inter partes review decision of the Patent Trial 

and Appeal Board (Board) finding claims 6–9 of U.S. Patent No. 6,363,345 (’345 patent) unpatentable as obvious 

over Hirsch1 in view of Martin.2 Apple Inc. v. Andrea Elecs. 

Corp., No. IPR2017-00626, 2020 WL 6324693 (P.T.A.B. 

Oct. 28, 2020) (Board Decision). 

This case is before us for a second time after we remanded part of the case back to the Board. Apple Inc v. 

Andrea Elecs. Corp., 949 F.3d 697 (Fed. Cir. 2020), vacating No. IPR2017-00626, 2018 WL 3414463 (P.T.A.B. July 

12, 2018) (Prior Board Decision). In the first appeal, we 

held the Board erred by not considering an argument made 

by petitioner Apple Inc. (Apple) on reply that we held did 

not present a new legal ground and properly responded to 

arguments raised by the patent owner’s response. Id. at 

706. The reply argument was that Martin discloses a “current minimum” and “future minimum” in an embodiment 

involving multiple subwindows. Id. at 699, 703–04. On 

remand, the Board considered the argument and found the 

claim limitations met but failed to properly analyze the motivation to combine Hirsch with Martin. We, therefore, 

1 H.G. Hirsch & C. Ehrlicher, Noise Estimation Techniques for Robust Speech Recognition, 1 International Conference on Acoustics, Speech, and Signal Processing 153 

(1995). J.A. 453–456. 2 R. Martin, An Efficient Algorithm to Estimate the 

Instantaneous SNR of Speech Signals, 92 Eurospeech 1093 

(1993). J.A. 457–460. 

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ANDREA ELECTRONICS CORPORATION v. APPLE INC. 3

vacate and remand. We affirm the Board’s finding that 

Martin discloses the limitations of claim 9.

BACKGROUND

A 

Our previous decision discusses the relevant technology, purported invention, and the prior art references. We 

therefore only provide details with particular relevance to 

this appeal. 

Claims 6 through 9 are directed to an apparatus for 

canceling noise in an audio signal by detecting, for each frequency bin of the audio signal, a noise threshold using “current magnitude,” “future minimum,” and “current 

minimum” values. ’345 patent, claims 6–9. The current 

magnitude is the value of the audio signal at a given time. 

See id. at col. 5 ll. 35–38, col. 6 ll. 23–28. The future minimum is reset periodically to the current magnitude, and 

then updated to the current magnitude whenever the current magnitude is smaller than the future minimum. Id.

at col. 6 ll. 24–32, col. 10 ll. 1–4, col. 10 ll. 9–12. The current 

minimum is initiated periodically with the value of the future minimum, and also follows the minimum value of the 

current magnitude. Id. at col. 6 ll. 33–41, col. 9 ll. 65–67, 

col. 10 ll. 5–8. The current minimum is used to determine 

the noise threshold, and the future minimum is used for 

initiation and refreshing of the current minimum. Id. at 

col. 6 ll. 38–57, col. 9 ll. 54–60. Based on the threshold, a 

portion of the signal that is estimated to be noise is removed in a technique called spectral subtraction. See id.

at col. 1 ll.19–21, col. 1 l. 58–col. 2 l. 10, col. 3 ll. 11–15, col. 

3 ll. 24–45, col. 6 ll. 38–41, 58–61. The ’345 patent purports 

to differ from the prior art because its method can be used 

on audio signals that contain continuous speech rather 

than requiring a signal that contains explicit non-speech 

segments. See id. at col. 2 l. 45–col. 3 l. 15, col. 3 ll. 24–45.

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4 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

Independent claim 1 and dependent claims 4 and 5 together recite an “apparatus for canceling noise” comprising 

a “threshold detector for setting a threshold for each frequency bin” of an audio signal “in accordance with a current minimum value,” which in turn is derived “in 

accordance with a future minimum value,” which itself is 

“determined as the minimum value of the magnitude . . . 

within a predetermined period of time.” Id. at col. 9 ll. 35–

64. The dependent claims at issue in this appeal recite how 

the current minimum and the future minimum values are 

determined: 

6. The apparatus according to claim 5, wherein 

said current minimum value is set to said future 

minimum value periodically.

7. The apparatus according to claim 6, wherein 

said future minimum value is replaced with the 

current magnitude value when said future minimum value is greater than said current magnitude 

value.

8. The apparatus according to claim 6, wherein 

said current minimum value is replaced with the 

current magnitude value when said current minimum value is greater than said current magnitude 

value.

9. The apparatus according to claim 5, wherein 

said future minimum value is set to a current magnitude value periodically; said current-magnitude 

value being the value of the magnitude of the corresponding frequency bin.

B 

The prior art reference Hirsch discloses a noise estimation technique for use with spectral subtraction. J.A. 453, 

Abstract. Like the ’345 patent, Hirsch explains that noise 

reduction is “usually done by detection of speech pauses to 

evaluate segments of pure noise” and that detecting speech 

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pauses “is a difficult task” in practical situations, specifically “if the background noise is not stationary.” J.A. 453. 

Hirsch acknowledges that “[s]ome approaches are known 

to avoid the problem of speech pause detection and to estimate the noise characteristics just from a past segment of 

noisy speech” and cites, among other references, Martin. 

J.A. 453 (citing reference [6]). Hirsch notes the “disadvantage of most approaches is the need of relatively long 

past segments of noisy speech.” J.A. 453. Hirsch then presents its spectral subtraction method for “estimat[ing] the 

spectral parameters of noise without an explicit speech 

pause detection” based on “calculat[ing] the noise level in 

each subband.” J.A. 453. Hirsch describes testing the accuracy of its method on “[d]ifferent stationary noise signals.” J.A. 454. 

Hirsch’s estimation method involves a noise estimate 

that “is calculated with a first order recursive system,” in 

which an adaptive threshold is calculated as a weighted 

sum of past spectral magnitude values in a frequency subband according to a specific recursive algorithm. J.A. 453.

Martin, referenced in Hirsch, is directed to noise power 

estimation with a focus on using the noise power estimation to compute signal-to-noise ratios. J.A. 457–58. Martin 

also briefly discusses the use of the power estimation in 

spectral subtraction applications to reduce noise in a signal. J.A. 460. Like the ’345 patent and Hirsch, Martin describes the conventional approach of acquiring noise 

statistics based on “noise only segments.” J.A. 457. Like 

the ’345 patent and Hirsch, Martin then explains that its 

proposed algorithm “does not need an explicit speech/nospeech decision to gather noise statistics.” J.A. 457. Martin asserts that its algorithm is “capable [of] track[ing] non 

stationary noise signals and has a low computational complexity.” J.A. 457. The Board found Martin discloses a specific noise-level estimation algorithm that includes the 

steps recited in claims 6 through 9. Board Decision, at *6–

7. In fact, Andrea does not dispute that Martin discloses 

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6 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

all of the limitations of claims 6 through 9, with the exception of the step in claim 9 “wherein said future minimum 

value is set to a current magnitude value periodically.” Appellant’s Br. 38–47. 

Martin’s algorithm operates in a periodic manner on a 

window and subwindow basis. Specifically, the noise 

power estimate is calculated based on one period of L samples of an audio signal—which make up a “window”—that 

is further divided into periods of W subwindows of M samples. J.A. 458. The Board found that Martin’s PPMMMMMMMM(ii)

(“minimum power of the last M samples”) value corresponds to the claimed future minimum value, Board Decision, at *4–5, PP�

xx(ii) (“smoothed power”) corresponds to the 

claimed current magnitude value, id. at *7 & n.9, and PP (ii)

(“estimated noise power”) corresponds to the claimed current minimum value, id. at *7. Martin teaches that at the 

beginning of every subwindow, PP (ii) (current minimum) is 

set equal to the minimum power of the last M samples (future minimum of the preceding subwindow) or, alternatively, to the minimum power of the last L samples (future 

minimum of the preceding window). J.A. 458. Then, during the current subwindow period, whenever PP�

xx(ii) (current 

magnitude) is smaller than PP (ii) (current minimum), PP (ii)

is updated with the smaller PP�

xx(ii) value. J.A. 458. During 

the subwindow period, by a samplewise comparison with 

PP�

xx(ii), PPMMMMMMMM(ii) (future minimum) is also updated to a 

smaller PP�

xx(ii) value whenever PP�xx(ii) is less than PPMMMMMMMM(ii). 

J.A. 458, Fig. 2 (Flowchart conditional: if PP�

xx(ii) < PPMMMMMMMM, 

then PPMMMMMMMM = PP�

xx(ii)).

Relevant to claim 9, Martin discloses that at the end of 

every subwindow period, PPMMMMMMMM (future minimum) for the 

next subwindow period is reset to maximum value PP mm . 

J.A. 458. Then, as just discussed, PPMMMMMMMM (future minimum) 

tracks PP�

xx(ii) (current magnitude) during the subwindow period whenever PP�

xx(ii) is less than PPMMMMMMMM. J.A. 458. 

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C 

In its first final written decision, the Board rejected the 

obviousness ground based on Hirsch and Martin because 

Apple relied on an embodiment of Martin that involved no 

subwindows (in other words WW = 1). Prior Board Decision, 

at *5–6. The Board first noted:

Initially, we agree with Petitioner that one skilled 

in the art would have considered Martin’s teachings, generally, when reviewing the teachings of 

Hirsch, as Martin is specifically referenced in 

Hirsch itself. 

Id. at *5. But proceeded to say “[n]evertheless, we are not 

persuaded that one skilled in the art would have modified 

Hirsch’s system based on the teachings of Martin in the 

particular manner proposed by Petitioner” because “a scenario from Martin where WW = 1 . . . is counter to the entire 

purpose of Martin.” Id. at *6. The Board concluded, therefore, that there was no reason why one skilled in the art 

would have modified Hirsch’s teaching in a manner contrary to the express disclosure of Martin. Id.

On remand, as directed by this court, the Board considered the combination of Hirsch and Martin that relied on a 

multiple-subwindows embodiment of Martin and concluded the embodiment included and disclosed a “future 

minimum” as well as the other limitations of claims 6–9. 

Board Decision, at *4–7. That included Martin’s disclosing 

of claim 9’s limitation that a “future minimum value is set 

to a current magnitude value periodically.” Id. at *7.

The Board also found that a skilled artisan would have 

been motivated to combine the references based on three

rationales. First, the Board said it had already sufficiently 

found a motivation in its prior decision when it said a 

skilled artisan would have generally considered Martin 

when looking at Hirsch, and Andrea did not appeal that 

determination. Id. at *7. Second, the Board reasoned that

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8 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

this court also decided the motivation-to-combine issue, 

when we noted that “Hirsch refers to Martin as a ‘known’ 

approach ‘to avoid the problem of speech pause detection 

and to estimate the noise characteristics just from a past 

segment of noisy speech.’” Id. (quoting Apple, 949 F.3d at 

703). And third, to the extent the first two reasons did not 

resolve the issue, the Board generically explained as a 

standalone analysis: 

[W]e agree with Petitioner that one skilled in the 

art would have considered using the multiple subwindow approach taught by Martin in Hirsch’s system. “When a work is available in one field, design 

incentives and other market forces can prompt variations of it, either in the same field or in another.” 

KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 401 

(2007). Based on the record before us, which includes an express suggestion in Hirsch to look to 

Martin’s teachings, Hirsch does not teach away 

from the proposed combination, and Petitioner has 

established by a preponderance of the evidence 

that one skilled in the art would have combined the 

teachings of Martin with those of Hirsch.

Id. at *8. Accordingly, the Board found claims 6–9 unpatentable over the combination of Hirsch and Martin. Id.

Andrea timely appealed to this court. We have jurisdiction under 28 U.S.C. § 1295(a)(4)(A).

DISCUSSION

Andrea appeals the Board’s findings that (1) Martin 

teaches the limitation of claim 9 that a “future minimum 

value is set to a current magnitude value periodically” and 

(2) a skilled artisan would have been motivated to combine 

Hirsch and Martin. The Board’s factual determinations 

are reviewed for substantial evidence and its legal determinations are reviewed de novo. In re Mouttet, 686 F.3d 

1322, 1330–31 (Fed. Cir. 2012). Substantial evidence is 

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“such relevant evidence as a reasonable mind might accept 

as adequate to support a conclusion.” Id. at 1331.

A 

Claim 9 requires that “the future minimum value is set 

to a current magnitude value periodically.” Before the 

Board, Apple argued that Martin’s algorithm meets this 

limitation with two steps. First, at the end of a subwindow 

period, PPMMMMMMMM (future minimum) is reset to a maximum 

value PPMM and, then, is set to the value of PP�

xx(ii) (current 

magnitude) at the beginning of the next subwindow period 

after PPMMMMMMMM and PP�

xx(ii) are compared. Board Decision, at *7. 

The Board credited the unrebutted testimony of Apple’s expert, Dr. Hochwald, that by resetting PPMMMMMMMM equal to PPMM xx, 

the next cycle of Martin’s algorithm sets PPMMMMMMMM to the 

smoothed power estimate PP�

xx(ii). Id. (citing J.A. 413 ¶ 140). 

Andrea argues the Board erred by relying on Apple’s 

expert’s testimony because, supposedly, the Board previously rejected the testimony when it rejected the singlesubwindow configuration of Martin for rendering the 

claims at issue obvious. Appellant’s Br. 39. According to 

Andrea, the Board provided no explanation as to why it relied on evidence from a previously rejected theory and, 

thus, acted arbitrarily and capriciously and reached a conclusion unsupported by substantial evidence. Id. at 39–44. 

We are unpersuaded. Dr. Hochwald’s testimony regarding the periodic setting of PPMMMMMMMM (future minimum) to 

PP�

xx(ii) (the current magnitude) relied on the periodicity of M 

samples in a subwindow, irrespective of whether a single 

subwindow or multiple subwindows are in a window. See

J.A. 413 ¶ 140. Because the Board originally rejected Apple’s obviousness theory for the more general reason that a 

single subwindow is contrary to Martin’s approach, the 

Board did not address or reject more specific issues including whether Martin discloses periodically setting PPMMMMMMMM to 

PP�

xx(ii) as explained by Dr. Hochwald. Prior Board Decision, 

at *4–6. There is nothing inconsistent about the Board’s 

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10 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

subsequent crediting of Dr. Hochwald’s testimony to find 

that claim 9 was met by Martin, once it considered that 

testimony in the context of multiple subwindows as directed by this court. 

Andrea also argues that Martin’s algorithm does not 

“periodically” set the future minimum value to the current 

magnitude value. Andrea points to the fact that PP�

xx(ii) is a 

signal that varies and is set as PPMMMMMMMM’s value only when 

PP�

xx(ii) is less than PPMMMMMMMM. Appellant’s Br. 42–47. But Andrea’s arguments never address the crucial detail that 

right before the beginning of a new subwindow, PPMMMMMMMM is set 

to a maximum value, which the Board found meant that at 

the beginning of each new subwindow PPMMMMMMMM gets set to 

PP�

xx(ii). Board Decision, at *7 (citing Dr. Hochwald’s testimony at J.A. 413 ¶ 140); see Appellee’s Br. 45–46 (explaining the Board’s finding based on PPMMMMMMMM being set to a 

maximum value); Appellant’s Reply Br. 28 (not addressing 

the effect caused by setting PPMMMMMMMM to a maximum value). 

Andrea has not shown the Board’s finding, that Martin discloses a “future minimum value is set to a current magnitude value periodically,” is unsupported by substantial 

evidence. 

B 

With respect to the motivation to combine Hirsch and 

Martin, Andrea argues the Board erred by saying that itself and this court previously resolved the issue. On this 

score we agree with Andrea. The Board and this court 

made broad, general statements relevant to, but not conclusive of, motivation to combine the relevant portions of 

the cited references in a manner that renders claims 6–9 

obvious. Hirsch does refer to Martin as a known approach 

to avoid the problem of speech pause detection to estimate 

noise and, based on that, it was reasonable for the Board to 

find that a skilled artisan would have considered Martin’s 

teachings generally when reviewing Hirsch. But neither 

the Board nor this court addressed why a skilled artisan 

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ANDREA ELECTRONICS CORPORATION v. APPLE INC. 11

would have specifically incorporated Martin’s noise power 

estimation algorithm into Hirsch’s spectral subtraction 

system or threshold calculation. See In re Sang Su Lee, 277 

F.3d 1338, 1343 (Fed. Cir. 2002) (discussing that motivation is needed for making the “specific combination that 

was made by the applicant”). In addition, neither the 

Board nor this court addressed any of the specific motivation issues contested by Andrea. These include, for example, whether: Hirsch shows a need for improvement in 

nonstationary noise environments and whether Martin 

provides such improvement, see, e.g., J.A. 1021–23; J.A. 

2497; Hirsch obviates the need to address the speech pause 

detection problem and, therefore, a skilled artisan would 

not have looked to Martin to address the problem, see, e.g.,

J.A. 1020; and Hirsch disparages Martin because of “the 

need of relatively long past segments of noise speech” and 

the “significant difference” in time requirements between 

Martin and Hirsch, see, e.g., J.A. 1019; J.A. 2495. The 

Board’s failure to provide any explanation as to why it accepted the prevailing arguments over the counter-arguments precludes us from being able to affirm the Board’s 

finding of motivation. See In re Nuvasive, Inc., 842 F.3d 

1376, 1383 (Fed. Cir. 2016) (“[I]t is not adequate to summarize and reject arguments without explaining why the 

PTAB accepts the prevailing argument.”).

The Board’s separate, standalone analysis of motivation is also inadequate for the same reason, i.e., the failure 

to address the specific motivation issues argued by the parties. The Board generically invoked “design incentives and 

other market forces,” concluded without explanation that 

Hirsch does not teach away, and relied on the general point 

that Hirsch mentions Martin. Id. at *8. In the face of Andrea’s specific contentions, these statements amount to a 

conclusory analysis that we have held to be an insufficient 

articulation of motivation to combine. See In re Nuvasive, 

842 F.3d at 1383.

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12 ANDREA ELECTRONICS CORPORATION v. APPLE INC. 

We also reject Apple’s reliance on the fact that, in its 

original decision, the Board found claim 25 unpatentable 

over the combination of Hirsch and Martin and that Andrea did not appeal the finding. Claim 25 recites an adaptive array comprising a plurality of microphones for 

receiving an audio signal. ’345 patent col. 11 ll. 5–7. In the 

context of claim 25, Apple presented why a skilled artisan 

would have been motivated to incorporate “conventional 

adaptive microphone arrays” from Martin into Hirsch, and 

the Board found that Andrea provided no evidence or argument to rebut Apple’s contentions. Prior Board Decision, 

at *7. However, any finding of motivation for claim 25 regarding the physical array of microphones is irrelevant to 

whether a skilled artisan would have been motivated to 

combine Martin’s algorithm into Hirsch’s algorithm. 

For the foregoing reasons, we affirm the Board’s decision finding that Martin discloses the limitations of claim 

9 of the ’345 patent but vacate the Board’s final written decision and remand for further findings on the motivation to 

combine Hirsch and Martin with respect to claims 6–9.

AFFIRMED IN PART, AND VACATED AND 

REMANDED IN PART

COSTS

No costs.

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