Case: 21-1248 Document: 33 Page: 1 Filed: 04/22/2022
NOTE: This disposition is nonprecedential.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 rep-
resented by FRANK D. LIU; ANDREW PETER ZAPPIA, Roches-
ter, NY.
JOSHUA JOHN FOUGERE, Sidley Austin LLP, Washing-
ton, 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: 2 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) ap-
peals the inter partes review decision of the Patent Trial
and Appeal Board (Board) finding claims 6–9 of U.S. Pa-
tent No. 6,363,345 (’345 patent) unpatentable as obvious
over Hirsch 1 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 re-
manded part of the case back to the Board. Apple Inc v.
Andrea Elecs. Corp.,
949 F.3d 697 (Fed. Cir. 2020), vacat-
ing 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 “cur-
rent 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 mo-
tivation to combine Hirsch with Martin. We, therefore,
1 H.G. Hirsch & C. Ehrlicher, Noise Estimation Tech-
niques for Robust Speech Recognition, 1 International Con-
ference 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.
Case: 21-1248 Document: 33 Page: 3 Filed: 04/22/2022
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 technol-
ogy, 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 fre-
quency bin of the audio signal, a noise threshold using “cur-
rent 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 mini-
mum is reset periodically to the current magnitude, and
then updated to the current magnitude whenever the cur-
rent 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 fu-
ture 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 re-
moved 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.
Case: 21-1248 Document: 33 Page: 4 Filed: 04/22/2022
4 ANDREA ELECTRONICS CORPORATION v. APPLE INC.
Independent claim 1 and dependent claims 4 and 5 to-
gether recite an “apparatus for canceling noise” comprising
a “threshold detector for setting a threshold for each fre-
quency bin” of an audio signal “in accordance with a cur-
rent 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 mini-
mum 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 mini-
mum 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 mag-
nitude value periodically; said current-magnitude
value being the value of the magnitude of the cor-
responding frequency bin.
B
The prior art reference Hirsch discloses a noise estima-
tion 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
Case: 21-1248 Document: 33 Page: 5 Filed: 04/22/2022
ANDREA ELECTRONICS CORPORATION v. APPLE INC. 5
pauses “is a difficult task” in practical situations, specifi-
cally “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 esti-
mate 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 “disad-
vantage of most approaches is the need of relatively long
past segments of noisy speech.” J.A. 453. Hirsch then pre-
sents 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 ac-
curacy of its method on “[d]ifferent stationary noise sig-
nals.” 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 sub-
band 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 estima-
tion 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 sig-
nal. J.A. 460. Like the ’345 patent and Hirsch, Martin de-
scribes 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/no-
speech decision to gather noise statistics.” J.A. 457. Mar-
tin asserts that its algorithm is “capable [of] track[ing] non
stationary noise signals and has a low computational com-
plexity.” J.A. 457. The Board found Martin discloses a spe-
cific 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
Case: 21-1248 Document: 33 Page: 6 Filed: 04/22/2022
6 ANDREA ELECTRONICS CORPORATION v. APPLE INC.
all of the limitations of claims 6 through 9, with the excep-
tion of the step in claim 9 “wherein said future minimum
value is set to a current magnitude value periodically.” Ap-
pellant’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 sam-
ples of an audio signal—which make up a “window”—that
is further divided into periods of W subwindows of M sam-
ples. J.A. 458. The Board found that Martin’s 𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 (𝑖𝑖)
(“minimum power of the last M samples”) value corre-
sponds to the claimed future minimum value, Board Deci-
sion, at *4–5, 𝑃𝑃�𝑥𝑥 (𝑖𝑖) (“smoothed power”) corresponds to the
claimed current magnitude value, id. at *7 & n.9, and 𝑃𝑃𝑛𝑛 (𝑖𝑖)
(“estimated noise power”) corresponds to the claimed cur-
rent minimum value, id. at *7. Martin teaches that at the
beginning of every subwindow, 𝑃𝑃𝑛𝑛 (𝑖𝑖) (current minimum) is
set equal to the minimum power of the last M samples (fu-
ture minimum of the preceding subwindow) or, alterna-
tively, to the minimum power of the last L samples (future
minimum of the preceding window). J.A. 458. Then, dur-
ing the current subwindow period, whenever 𝑃𝑃�𝑥𝑥 (𝑖𝑖) (current
magnitude) is smaller than 𝑃𝑃𝑛𝑛 (𝑖𝑖) (current minimum), 𝑃𝑃𝑛𝑛 (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 𝑃𝑃𝑚𝑚𝑚𝑚𝑚𝑚 .
J.A. 458. Then, as just discussed, 𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 (future minimum)
tracks 𝑃𝑃�𝑥𝑥 (𝑖𝑖) (current magnitude) during the subwindow pe-
riod whenever 𝑃𝑃�𝑥𝑥 (𝑖𝑖) is less than 𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 . J.A. 458.
Case: 21-1248 Document: 33 Page: 7 Filed: 04/22/2022
ANDREA ELECTRONICS CORPORATION v. APPLE INC. 7
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 teach-
ings, 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 sce-
nario from Martin where 𝑊𝑊 = 1 . . . is counter to the entire
purpose of Martin.” Id. at *6. The Board concluded, there-
fore, that there was no reason why one skilled in the art
would have modified Hirsch’s teaching in a manner con-
trary to the express disclosure of Martin. Id.
On remand, as directed by this court, the Board consid-
ered the combination of Hirsch and Martin that relied on a
multiple-subwindows embodiment of Martin and con-
cluded 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
Case: 21-1248 Document: 33 Page: 8 Filed: 04/22/2022
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 sub-
window approach taught by Martin in Hirsch’s sys-
tem. “When a work is available in one field, design
incentives and other market forces can prompt var-
iations 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 in-
cludes 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 un-
patentable over the combination of Hirsch and Martin. Id.
Andrea timely appealed to this court. We have juris-
diction 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 deter-
minations are reviewed de novo. In re Mouttet,
686 F.3d
1322, 1330–31 (Fed. Cir. 2012). Substantial evidence is
Case: 21-1248 Document: 33 Page: 9 Filed: 04/22/2022
ANDREA ELECTRONICS CORPORATION v. APPLE INC. 9
“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 𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀 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 ex-
pert, Dr. Hochwald, that by resetting 𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 equal to 𝑃𝑃𝑀𝑀𝑎𝑎𝑥𝑥 ,
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 previ-
ously rejected the testimony when it rejected the single-
subwindow 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 re-
lied on evidence from a previously rejected theory and,
thus, acted arbitrarily and capriciously and reached a con-
clusion unsupported by substantial evidence. Id. at 39–44.
We are unpersuaded. Dr. Hochwald’s testimony re-
garding 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 Ap-
ple’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 includ-
ing 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
Case: 21-1248 Document: 33 Page: 10 Filed: 04/22/2022
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 di-
rected 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 An-
drea’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 testi-
mony at J.A. 413 ¶ 140); see Appellee’s Br. 45–46 (explain-
ing 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 dis-
closes a “future minimum value is set to a current magni-
tude 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 it-
self 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 con-
clusive 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
Case: 21-1248 Document: 33 Page: 11 Filed: 04/22/2022
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 motiva-
tion 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 motiva-
tion issues contested by Andrea. These include, for exam-
ple, 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 ac-
cepted the prevailing arguments over the counter-argu-
ments 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 sum-
marize and reject arguments without explaining why the
PTAB accepts the prevailing argument.”).
The Board’s separate, standalone analysis of motiva-
tion is also inadequate for the same reason, i.e., the failure
to address the specific motivation issues argued by the par-
ties. 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 An-
drea’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.
Case: 21-1248 Document: 33 Page: 12 Filed: 04/22/2022
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 An-
drea did not appeal the finding. Claim 25 recites an adap-
tive 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 argu-
ment to rebut Apple’s contentions. Prior Board Decision,
at *7. However, any finding of motivation for claim 25 re-
garding 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 deci-
sion finding that Martin discloses the limitations of claim
9 of the ’345 patent but vacate the Board’s final written de-
cision 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.
