NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________ 

SLOT SPEAKER TECHNOLOGIES, INC.,

Appellant

v.

APPLE INC.,

Cross-Appellant

______________________ 

2015-2038, 2015-2039

______________________ 

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 

IPR2014-00235.

______________________ 

Decided: February 17, 2017

______________________ 

 KENNETH J. HALPERN, Perkins Coie, LLP, Palo Alto, 

CA, argued for appellant. Also represented by ERIC L.

WESENBERG, CHRISTOPHER LEE KELLEY. 

 MARK CHRISTOPHER FLEMING, Wilmer Cutler Pickering Hale and Dorr LLP, Boston, MA, argued for crossappellant. Also represented by BRYAN S. CONLEY, KEVIN 

GOLDMAN; NINA S. TALLON, DAVID LANGDON CAVANAUGH, 

Washington, DC; NATALIE POUS, New York, NY.

______________________ 
2 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

Before LOURIE, DYK, and O’MALLEY, Circuit Judges.

O’MALLEY, Circuit Judge. 

Appellee/Cross-Appellant Apple Inc. (“Apple”) filed a 

petition for inter partes review of various claims of U.S. 

Patent No. 7,433,483 (“the ’483 patent”), assigned to 

Appellant/Cross-Appellee Slot Speaker Technologies, Inc.1

(“Slot Speaker”). The Patent Trial and Appeal Board

(“the Board”) instituted review on claims 1–3 of the ’483 

patent, and concluded that claims 1 and 2 would have 

been obvious over prior art, but claim 3 would not have

been obvious. Apple Inc. v. THX Ltd., IPR2014-00235, 

2015 WL 3638275 (P.T.A.B. June 9, 2015) (“Board Decision”). Slot Speaker appeals the Board’s decision on 

claims 1 and 2; Apple cross-appeals the Board’s decision 

on claim 3. We conclude that substantial evidence supports the Board’s finding that claims 1 and 2 of the ’483 

patent would have been obvious. We conclude that the 

Board erred, however, in ruling that claim 3 of the ’483 

patent would not have been obvious. We therefore affirmin-part and reverse-in-part. 

I. BACKGROUND

A. The ’483 Patent

The ’483 patent is directed to a sound reproduction 

system with a speaker configuration providing a “relatively narrow sound output region in relation to the size of 

the speaker face(s) utilized in the sound reproduction 

system.” ’483 patent, col. 3 ll. 22–26. Figures 1 and 2B of 

the ’483 patent, shown below, depict the configuration of 

the speaker and sound duct walls. The speaker 107 is 

mounted perpendicular to the sound duct 115, such that 

 

1 Slot Speaker Technologies, Inc. was formerly 

known as THX, Ltd.
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 3

sound is redirected from the speaker, through the sound 

duct, and exits an output aperture 106. The duct wall 

103 opposite the speaker has a sound reflecting surface, 

while sound damping material is added to the sidewalls 

104 and 105 and the back wall 112. 

Id. figs. 1–2. 

The sound damping material reduces standing waves 

inside the duct. Standing waves occur when sound is 

trapped between opposite reflecting walls, at frequencies 

where the distance between the walls is an integer number of half-wavelengths. These unwanted resonances 

diminish the quality of the projected sound. Because the 

speaker is narrow vertically, standing waves do not form 

in the vertical direction and, thus, sound damping material is not required on the top and bottom surfaces. The 

’483 patent teaches the elimination of standing waves in 

the horizontal direction by placing sound damping material on the sidewalls and back wall of the sound duct. Id.

col. 8, ll. 17–28. 

The Board instituted review on claims 1–3 of the ’483 

patent. Claim 1 of the ’483 patent recites:

A narrow profile sound system, comprising:

a drive unit disposed on a mounting surface, said 

mounting surface forming a barrier acoustically 

isolating the drive unit’s forward radiation from 

its rearward radiation;
4 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

a sound reflecting surface facing the drive unit 

and substantially parallel with the mounting surface; and

sound damping material disposed between said 

sound reflecting surface and the mounting surface, the sound reflecting surface and the mounting surface defining a bottom and top of a narrow 

sound duct terminating in an elongate output slot, 

with the sound damping material forming the 

sides of the sound duct, whereby forward radiation from the drive unit is turned at a substantially right angle and channeled along a straight path 

towards the output slot;

wherein the sound damping material forms an 

outer shape of the sound duct which reduces 

sound reflections at the end of the sound duct opposite the output slot and thereby mitigates 

standing waves.

Id. col. 29, l. 62–col. 30, l. 13.

Claim 2 depends from claim 1, adding the limitation 

that “sound emanating from the output slot is characterized by a wide horizontal dispersion angle and a narrow 

vertical dispersion angle, as a result of the elongate shape 

of the output slot.” Id. col. 30, ll. 14–19.

Claim 3 depends from claim 1 and includes the additional limitation that the “sound damping material forms 

a back wall of the sound duct, said back wall substantially 

following a curved contour of a portion of a drive unit cone 

farthest opposite from the output slot.” Id. col. 30, ll. 20–

33.
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 5

B. Prior Art

The Board instituted based on three prior art references; two are relevant to this appeal. 2

1. Tomonori 

Tomonori et al., EP 0744880 A1 (“Tomonori”), discloses a speaker mounted perpendicular to a sound duct, such 

that sound from the speaker is directed through the duct 

and exits a narrow aperture positioned along the side of 

the television screen, as shown below.

 

2 The Board instituted based in part on U.S. Patent 

No. 3,687,220 (“Virva” or “the ’220 patent”), which describes a speaker system that augments the bass-range 

response of two small speakers by using a serpentine 

enclosure behind the drive units to create a tuned air 

column. Virva teaches that “all inside surfaces of the 

enclosure should be treated with acoustically absorbing 

material to prevent spurious resonances or standing 

waves from developing within in the enclosure.” ’220 

patent, col. 3, ll. 42–46. In its Final Written Decision, the 

Board found that a person of ordinary skill in the art 

would not have utilized the disclosure of Virva in modifying Tomonori. No party appeals that aspect of the decision, so we do not address this reference further.
6 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

Tomonori, figs. 1, 7. Tomonori recognizes that one of the 

problems of directing sound through a duct is the presence of “standing waves.” Id. col. 2, ll. 12–18. Tomonori 

describes that standing waves are produced when “some 

of the sound waves are reflected owing to a marked 

change in the acoustic impedance at the tube open end 

and return toward the speaker 12 to produce standing 

waves.” Id. col. 2, ll. 46–49. Standing waves create 

resonant frequencies that interfere with other soundwaves and degrade the quality of sound leaving the sound 

duct. 

To eliminate the formation of standing waves, 

Tomonori provides two solutions. First, Tomonori locates 

the speaker at an “anti-node,” one-third to one-fifth of the 

distance of the total length of the sound tube from its 

closed back end. Id. col. 2, ll. 45–50. Figure 16 illustrates 

this configuration.

Id. fig. 16. Second, Tomonori teaches that the duct should 

be “internally provided with a sound absorbing material . . . adapted to absorb standing waves.” Id. col. 1, l. 57–

col. 2, l. 5. To this end, Tomonori discloses adding sound 

absorbing material to the back wall of the sound duct. By 

absorbing and eliminating the standing waves, Tomonori 

teaches that the sound quality is improved. Id. col. 8, ll. 

19–25. 

2. Sadaie

Sadaie et al., WO Pub. No. 00/52958 (“Sadaie”), discloses a small-sized speaker system with a narrow-profile 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 7

configuration and a speaker driver positioned perpendicular to a sound duct. Sadaie’s speaker system is designed 

to enhance speaker response at the low end of the frequency spectrum. Sadaie teaches that the sidewalls and 

back wall of the sound duct may be lined with two different layers, “pressure absorbing material” and “acoustic 

material,” which both shapes the path through which 

sound travels and regulates pressure and unwanted noise 

inside the duct. J.A. 581–82.

As depicted in Figure 17 (side view, below left), the 

speaker driver 11 is mounted inside an enclosure 10. As 

shown in the overhead view in Figure 18 (below right), 

sound travels from the speaker driver through a sound 

duct referred to as a “sound guiding part 40.” The sound 

duct, or sound guiding part, has two sections: a “sound 

source space 41” that encompasses the area beneath the 

speaker driver, and a “sound path 42” that extends from 

the sound source space to the output aperture 45. 

Sadaie, figs. 17–18; J.A. 609–10. The top wall of the 

Sadaie sound duct is formed by the speaker enclosure, the

bottom wall is referred to as the “wall body 50”, and an 

“intermediate member 30” forms the sidewalls and back 

wall. Sadaie teaches that some or all of the wall surface 

may be covered with a “pressure absorbing material 31” 

to define the shape of the sound duct. As seen in Figure 

18, pressure absorbing material may be added to the 

surface of the intermediate member to create a sound 

path with curved walls.
8 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

This pressure absorbing material is added to “enable[] 

control of the bass reproduction capability, output characteristics, noise, wind noise, and the like of the obtained 

speaker system.” J.A. 582. The pressure absorbing 

material “does not require sound absorbency but may 

have sound absorbency.” J.A. 582. Sadaie teaches that 

sound absorbency is particularly beneficial to “improve 

sound quality” when it is used to reduce high frequency 

sounds like wind noise. J.A. 582. 

Sadaie teaches that the pressure absorbing material 

may be further padded with an “acoustic material 32.” 

Like the pressure absorbing material, the acoustic material “does not require sound absorbency but may have 

sound absorbency.” J.A. 583. In the preferred embodiment, the acoustic material is a sound damping material 

such as a felt or soft film. J.A. 583. Sadaie explains that 

the acoustic material “may be provided on an entire 

surface of the wall surface of the sound guiding part” or it 

“may be disposed on any appropriate position on the wall 

surface according to the purpose.” J.A. 582.

C. Procedural History

Slot Speaker sued Apple in the Northern District of 

California, alleging infringement of U.S. Patent No. 

8,457,340 (“the ’340 patent”), which shares a common 

specification with the ’483 patent. Thereafter, Apple filed 

(1) a petition for inter partes review of claims 1–6, 8, 10, 

and 18–20 of the ’483 patent, and (2) a petition requesting

inter partes review of claims 1–7 and 29–34 of the ’340 

patent. The Board instituted inter partes review on 

claims 1–3 of the ’483 patent, but declined to institute 

inter partes review on any claim of the ’340 patent. The 

parties stipulated to a stay of the civil proceedings. 

The Board issued its Final Written Decision on the 

patentability of the ’483 patent on June 9, 2015, determining that claims 1 and 2 would have been obvious over 

Tomonori in view of Sadaie, but that claim 3 would not 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 9

have been obvious. Board Decision, 2015 WL 3638275, at 

*2. Both parties appealed from those respective aspects of 

the Board’s decision which were adverse to them. We 

have jurisdiction over Slot Speaker’s appeal and Apple’s 

cross-appeal under 35 U.S.C. §§ 141(c), 319 and 28 U.S.C. 

§ 1295(a)(4)(A).

II. STANDARD OF REVIEW

Obviousness is a question of law based on underlying 

factual findings, including the scope and content of prior 

art references and the existence of a reason to combine 

those references. In re Hyon, 679 F.3d 1363, 1365–66 

(Fed. Cir. 2012). We uphold the Board’s factual findings 

unless they are not supported by substantial evidence, 

while we review the Board’s legal conclusions de novo. 

Dynamic Drinkware, LLC v. Nat’l Graphics, Inc., 800 F.3d 

1375, 1378 (Fed. Cir. 2015). A finding is supported by 

substantial evidence if a reasonable mind might accept 

the evidence to support the finding. In re Jolley, 308 F.3d 

1317, 1320 (Fed. Cir. 2002).

III. DISCUSSION

A. Obviousness of Claims 1 and 2

Slot Speaker appeals the Board’s determination that 

claims 1 and 2 of the ’483 patent would have been obvious 

over Tomonori in light of Sadaie. Neither party challenges the Board’s claim construction of the term “sound 

reflecting surface”: “a surface that redirects sound waves 

output from a speaker, not made of sound damping material.” Board Decision, 2015 WL 3638275, at *4–7. Under 

this construction, the Board found that Tomonori discloses every limitation of claim 1 of the ’483 patent, except for 

“sound damping material forming sides of the sound 

duct.” Id. at *8–10. 

Sound damping material is used in the ’483 patent on 

the sidewalls and optionally the back wall of the sound 

duct, but not on the top or bottom surfaces. This configu-
10 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

ration prevents “expansion of the sound waves in a rearward direction, [] thereby reducing potential interference 

or other undesirable acoustic effects.” ’483 patent, col. 22, 

l. 64–col. 23, l. 3. Claim 1 further specifies that “sound 

damping material forms an outer shape of the sound duct

which reduces sound reflections at the end of the sound 

duct opposite the output slot and thereby mitigates standing waves.” Id. col. 30 ll. 10–13. The Board determined 

that the sound damping material Tomonori discloses at 

the closed end of its sound tube “fulfills the same function 

disclosed in the ’483 patent even though it does not form 

the sides of the sound duct.” Board Decision, 2015 WL 

3638275, at *12. 

The Board then analyzed whether one of ordinary 

skill in the art would have been motivated to combine 

Sadaie with Tomonori to use sound damping material to 

form the sides of Tomonori’s sound duct. The Board 

concluded that Sadaie shows that the use of sound damping material along the sides of a sound duct is “a known 

configuration to suppress standing waves inside a duct.” 

Id. Apple’s expert Dr. Vipperman explained that Sadaie 

used a sidewall sound damping method to enable “the 

sharpness of a fundamental wave resonance of a standing 

wave determined by the length of the sound path . . . to be 

suppressed because a substantial length of the sound path 

cannot be primarily determined.” J.A. 530. The Board 

found that “[e]xtending the damping material of Tomonori 

along the sidewalls of the duct, as taught by Sadaie, 

would have been one of a limited number of known solutions further minimizing the presence of spurious resonances and standing waves inside the duct.” Board 

Decision, 2015 WL 3638275, at *12 (quotation omitted). 

In light of Sadaie’s teachings, the Board found that a 

person of ordinary skill in the art would have been motivated to modify Tomonori by using sound damping material along the sides of the narrow sound duct. 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 11

Slot Speaker disputes the Board’s use of Sadaie to 

disclose the extension of sound damping material along 

the sidewalls of the duct. We conclude, however, that

substantial evidence supports the Board’s findings that

(1) Sadaie discloses the extension of sound damping 

material along the sidewalls of the duct, and (2) there is a 

sufficient teaching or motivation to combine Sadaie and 

Tomonori. 

The plain language of Sadaie discloses the extension 

of sound damping material along the sidewalls of the 

duct. Sadaie teaches that the wall surface (the surface of 

the intermediate member) may be “pressure absorbing 

material” and an “acoustic material,” and that “[t]he 

pressure absorbing material does not require sound 

absorbency but may have sound absorbency,” and in the 

preferred embodiment, the pressure absorbing material is 

a sound damping material such as foam. J.A. 582. The 

acoustic material “does not require sound absorbency but 

may have sound absorbency,” and, in the preferred embodiment, the acoustic material is a sound damping 

material such as felt. J.A. 583. Sadaie teaches that the 

pressure absorbing material and acoustic material may 

extend along the sidewalls from the area near the speaker 

to the output aperture. 

Sadaie further teaches that pressure absorbing material can be used to mitigate standing waves: 

[T]he pressure absorbing material in the defined 

section 31 enables the sharpness of a fundamental 

wave resonance of a standing wave determined by 

the length of the sound path 42 to be suppressed 

because a substantial length of the sound path 

cannot be primarily determined.

J.A. 584. The pressure absorbing material of Sadaie may 

absorb both pressure and sound from the standing wave. 

Sadaie explains that “the pressure absorbing material in 

combination with the acoustic material allows the slight 
12 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

sound absorption that exists in the pressure absorbing 

material (for example, urethane foam) in the bass range 

to be nearly zero, thereby further suppressing the energy 

loss in the bass range.” J.A. 583. Given these teachings, 

we conclude that the Board did not commit error when it 

referred to Sadaie’s mitigation of standing waves with 

sound damping material, rather than pressure absorbing 

material. 

We also conclude that substantial evidence supports 

the Board’s determination that Sadaie teaches sidewallonly placement of the sound damping material. In fact, 

Slot Speaker’s counsel conceded during the oral hearing 

before the Board that Sadaie does not only teach the 

placement of sound absorbing material on all sides of the 

duct:

JUDGE MURPHY: I mean, if we only focus on 

the structure, Sadaie -- even in the paragraph 

that you have reproduced for us on slide 28, bottom of page 12 of Sadaie, it indicates that the 

sound absorbing material, which is in that pressure adjustment section 32, which is described as 

felt or a thin film of some sort, or soft film in Sadaie, it may be only on the wall surface of one side 

of the sound path, so that's one side of a sound 

duct. It could be one side. It could be two sides. 

It could be all sides. It's not only all sides, right? 

MR. KELLEY: It is not only all sides, you're correct.

J.A. 373 ll. 2–13 (emphasis added). Slot Speaker implicitly concedes that Sadaie teaches sidewall-only placement, 

because Slot Speaker reads Sadaie as allowing the 

“placement of pressure absorbing material with a sound 

absorbing surface ‘on any appropriate position on the wall 

surface according to the purpose.’” Slot Speaker Opening 

Br. at 57 (quoting J.A. 582). 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 13

Despite this concession, Slot Speaker argues that 

sidewall-only placement is a species within the genus of 

placement of sound absorbing material on any appropriate position of the wall surface. We disagree with Slot 

Speaker’s interpretation of the surfaces on which sound

damping material can be placed. Sadaie distinguishes 

between the intermediate member surface (sidewalls and 

back wall), the “wall body” surface (the bottom wall 

opposite the speaker), and the speaker enclosure (the top 

wall that holds the speaker driver). Sadaie teaches that 

pressure absorbing material and acoustic material are 

placed on the intermediate member. J.A. 581–83; 

J.A. 808–11 (¶¶ 22–26). Sadaie further discloses particular embodiments, claims 9 and 19, where sound absorbing 

material is placed only along the intermediate member. 

J.A. 594; J.A. 596. We therefore conclude that Sadaie 

teaches the placement of two different types of sound 

damping material on its sidewalls and back wall, not its 

top wall or bottom wall.3

Having concluded that Tomonori and Sadaie teach all 

of the elements of claim 1, we turn to whether substantial 

evidence supports the Board’s finding of a teaching or 

motivation to combine these references. “An invention is 

not obvious just ‘because all of the elements that comprise 

the invention were known in the prior art;’ rather a 

finding of obviousness at the time of invention requires a 

‘plausible rational [sic] as to why the prior art references 

 

3 Slot Speaker failed to raise the argument below 

that placing the pressure absorbing material of Sadaie in 

Tomonori’s duct would eliminate the “straight path” 

limitation recited in claim 1 of the ’483 patent. Even if 

raised, moreover, we would reject its implications because 

Tomonori discloses a straight duct; Sadaie, accordingly,

need not disclose a straight duct in order to reach the 

conclusion that claims 1 and 2 were obvious.
14 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

would have worked together.’” Broadcom Corp. v. Emulex 

Corp., 732 F.3d 1325, 1335 (Fed. Cir. 2013) (quoting 

Power-One, Inc. v. Artesyn Techs., Inc. 599 F.3d 1343, 

1351 (Fed. Cir. 2010)). “An obviousness determination 

requires that a skilled artisan would have perceived a 

reasonable expectation of success in making the invention 

in light of the prior art.” Amgen Inc. v. F. Hoffman-La 

Roche Ltd., 580 F.3d 1340, 1362 (Fed. Cir. 2009) (citation 

omitted). 

The Board did not conclude that a person of ordinary 

skill in the art simply would have substituted Sadaie into 

Tomonori. Instead, the Board found that such a person 

would have recognized, based on the teachings of Sadaie, 

that the sound damping material along Tomonori’s back 

wall could be extended along Tomonori’s sidewalls to 

suppress unwanted soundwaves. Board Decision, 2015 

WL 3638275, at *12–13. 

Slot Speaker attempts to reframe “success” in this inquiry as the production of full-range sound, which Slot 

Speaker contends would be impossible through the combination of Tomonori and Sadaie, given that Sadaie

focuses on the production of low frequency bass sounds. 

We agree with the Board, however, that the ’483 patent 

claims do not require absorption of specific resonances at 

specific frequencies, nor any specific threshold with 

respect to signal loss. They merely require sound damping material on the sidewalls, and material that absorbs 

any type of sound satisfies the “sound damping material”

element. Id. 

The relevant inquiry is whether a person of ordinary 

skill in the art would have had a reasonable expectation 

of success in modifying Tomonori in light of Sadaie to 

absorb unwanted soundwaves. It is irrelevant whether 

Tomonori and Sadaie together would be less effective than 

Sadaie alone at avoiding the absorption of certain low 

frequencies. See, e.g., In re Kahn, 441 F.3d 977, 990 (Fed. 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 15

Cir. 2006). And Slot Speaker’s argument that Tomonori 

and Sadaie are incompatible because they are directed to 

different goals fails because a person of ordinary skill

would not have ignored Sadaie’s teachings on the use of 

sound damping materials on its sidewalls to absorb unwanted soundwaves just because Sadaie discloses that its 

material also absorbs pressure. KSR Int’l Co. v. Teleflex 

Inc., 550 U.S. 398, 420 (2007) (“[A]ny need or problem 

known in the field of endeavor at the time of invention 

and addressed by the patent can provide a reason for 

combining the elements in the manner claimed.”).

To this effect, Tomonori and Sadaie both disclose multiple configurations for sound ducts. Tomonori also discusses that the use of sound absorbing material was a 

known solution to suppress standing waves. Tomonori, 

col. 1, l. 57–col. 2 l. 3. Sadaie also discloses that the use of 

sound absorbing material along the sides of a sound duct 

was a known configuration to suppress unwanted soundwaves. J.A. 582. Finally, Apple’s expert Dr. Vipperman

explained that the addition of Sadaie’s sidewall-only 

sound damping material would be a routine design choice, 

as “one of a limited number of known solutions to minimize the presence of standing waves and other unwanted

soundwaves inside the duct.” J.A. 531. Based on this 

showing, we conclude that substantial evidence supports 

the Board’s finding that a person of ordinary skill in the 

art would have recognized that Sadaie’s sidewall-only 

placement of sound damping material suppresses standing waves. 

On dependent claim 2, the Board found that Tomonori 

disclosed “an elongate output slot and emit[ted] sound 

characterized by a wide horizontal dispersion angle and a 

narrow vertical dispersion angle as a result of the elongate output slot.” Board Decision, 2015 WL 3638275, at 

*14. Given that claim 2 adds the additional limitation 

“wherein sound emanating from the output slot is characterized by a wide horizontal dispersion angle and a nar-
16 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

row vertical dispersion angle as a result of the elongate 

output slot,” ’483 patent, col. 30, ll. 14–19, the Board 

concluded that Apple had established by a preponderance 

of the evidence that the combination of Tomonori and 

Sadaie would have rendered claim 2 obvious to a person of 

ordinary skill in the art. Because Slot Speaker has not 

disputed the Board’s findings with respect to claim 2 

specifically, we also affirm the Board’s determination of 

obviousness on claim 2.

For these reasons, we affirm the Board’s determination that claims 1 and 2 would have been obvious over 

Tomonori in view of Sadaie. 

B. Obviousness of Claim 3

Apple cross-appeals from the Board’s determination 

that claim 3 of the ’483 patent would not be rendered 

obvious by Tomonori in view of Sadaie. As noted above, 

claim 3 adds the additional limitation to claim 1, “wherein 

said sound damping material forms a back wall of the 

sound duct, said back wall substantially following a 

curved contour of a portion of a drive unit cone farthest 

opposite from the output slot.” ’483 patent, col. 30, ll. 20–

23. The Board concluded that Tomonori failed to disclose 

sound damping material that followed a curved contour of 

a portion of the speaker cone farthest opposite the output 

slot, as required by claim 3. Board Decision, 2015 WL 

3638275, at *15. The Board then concluded that Sadaie’s 

pressure/sound damping material (labeled as 31 and 32) 

does not follow the curved portion of the speaker cone 21

“farthest opposite from the output slot [45]” to form a 

back wall to the sound duct. Id. 

The Board also found that Apple’s expert failed to explain why a person of ordinary skill in the art would have 

relied on Sadaie’s disclosure of a preferred embodiment 

where the “sound guiding part [40] has a sound source 

space [41] defined according to a peripheral edge portion 

of the above speaker unit,” to modify the shape of the 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 17

sound damping material by following the curved contour 

of a speaker cone, as required by claim 3. Id. at *16.

We first assess whether all of the elements of claim 3 

can be found in either Tomonori or Sadaie. We disagree 

with the Board’s conclusion that Apple and its expert 

failed to identify “any examples in the prior art of sound 

damping material forming a back wall of a sound duct 

that follows a curved contour of a speaker cone.” Id. at 

*15 (emphasis in original). The Board focused its analysis 

on Figure 18 of Sadaie to find that the sound damping 

material did not follow the curved portion of the speaker 

cone farthest opposite from the output slot to form the 

back wall. But the claim 3 limitation requires a “back 

wall substantially following a curved contour of a portion 

of a drive unit cone farthest opposite from the output 

slot.” ’483 patent, col. 30, ll. 19–23 (emphasis added). 

There is no requirement that the back wall follow the 

entire contour of the speaker cone. Sadaie expressly 

discloses embodiments where the back wall substantially 

follows the curve of the speaker cone farthest opposite the 

output slot (in Figures 3 and 4 below). Indeed, the Board 

acknowledged that Figure 4 of Sadaie, shown below,

“shows a circular peripheral outer edge of Sadaie’s sound 

guide.” Board Decision, 2015 WL 3638275, at *15 n.12. 

Sadaie, figs. 3–4; J.A. 599–600.
18 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

In addition, Sadaie teaches a back wall covered with 

sound damping material. Sadaie teaches that the sound 

guiding part 40 has two sections: the sound source space 

41 encompassing the area beneath the speaker driver; 

and a sound path 42 extending from the sound source 

space to the output duct 45. These surfaces form the side 

and back walls of the duct. Sadaie teaches that: 

[T]he pressure adjustment section 32 may be [1] 

equipped on the entire wall surface of the sound 

path 42, or [2] it may be equipped only on the wall 

surface of one side of the sound path 42, or [3] it 

may be equipped on the wall surface from the 

sound source space 41 to the sound path 42. 

J.A. 582–83 (bracketed characters added). As discussed 

above, we agree with Apple that Sadaie refers to “pressure adjustment section 32” as containing acoustic material. Sadaie further teaches that the acoustic material 

may be placed anywhere on the sound guiding part 40: 

The pressure adjustment section 32 may be provided on an entire surface of the wall surface of 

the sound guiding part 40. The pressure adjustment section 32 may be disposed on any appropriate position on the wall surface according to the 

purpose. 

J.A. 582. Thus, Sadaie discloses that the acoustic material may be placed on the back wall of the sound duct.

Figure 18, supra, shows Example [1], where the pressure adjustment section is equipped along the entire wall 

of the sound path 42. Figure 18 also shows Example [1] 

because the acoustic material extends along the surface 

walls of the sound path, but does not cover the surface 

walls of the sound source space. Example [3] teaches an 

embodiment where the pressure absorbing material and 

acoustic material extend along both the sound path 42

and the sound source space 41. In this embodiment, both 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 19

of these materials would extend along the back wall of the 

sound duct (the wall furthest from the output duct 45). 

The parties do not dispute that acoustic material can be 

sound absorbing material. Thus, Example [3] teaches a 

back wall substantially following a curved contour of a 

portion of a drive unit cone farthest opposite from the 

output slot, made of sound absorbing material. 

We further conclude that claim 3 does not require “direct proximity” between the speaker driver and the back 

wall, and, thus, that the presence of a gap between Sadaie’s back wall and speaker cone is not inconsistent with 

the teachings of the ’483 patent. Indeed, specific embodiments in the ’483 patent include gaps between the back 

wall of the duct and the speaker driver. ’483 patent, col. 

9, ll. 20–32 (the edge of the speaker cone is not required to 

“match[]the contours of the edge of the cylindrical housing” but may vary such that “the cone may be smaller 

than the diameter of the cylindrical housing 405, or else 

the speaker 407 may be positioned with an offset from 

(above or below) the top edge of the cylindrical housing 

405.”).

We now consider whether a person of ordinary skill in

the art would have found a sufficient teaching or motivation to modify Tomonori’s straight back wall to the curved 

shape described in Sadaie, even though there is no explicit teaching to that effect in Sadaie. There need not be an 

explicit teaching to combine references in the prior art. 

Depending on the nature of the technology and the 

knowledge of those skilled in the art, a motivation to 

make a particular modification may be a matter of common sense. KSR, 550 U.S. at 418, 420–21. While we do 

not rely on common sense lightly, where, as here, the only 

evidence of record supports the conclusion that the modification at issue is readily within the ken of those skilled 

in the art, it is appropriate to do so.
20 SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 

In addition to the evidence offered to support the finding of a motivation to combine Sadaie with Tomonori to 

practice claims 1 and 2, Apple proffered expert testimony 

that it would not have been challenging to modify Tomonori’s back wall to a curved one: 

Limitation 3(b) recites ‘said back wall substantially following a curved contour of a portion of a 

drive unit cone farthest opposite from the output 

slot.’ . . [I]t would have been obvious to combine 

Tomonori with the teachings of Virva and Sadaie. 

It would have been obvious to one of ordinary skill 

in the art to use a back wall that substantially follows a curved contour of a portion of a drive unit 

cone farthest opposite from the output slot. For 

example, Sadaie discloses that ‘[i]n a preferred 

embodiment, the above sound guiding part has a 

sound source space defined according to a peripheral edge portion of the above speaker unit’. . . 

Straight and curved backwalls opposite a sound 

duct aperture are two among a limited number of 

options for shaping the back wall of a sound duct, 

and have both been commonly used in loudspeaker design with predictable results. Given the 

ubiquity of curved and straight back walls, one of 

skill in the art would recognize the functions associated with each structure and the attendant benefits, and would select one for its known 

properties. Thus, it would have been obvious to 

shape the back wall of Tomonori to follow a contoured edge of a drive unit, as taught by Sadaie 

and doing so would have been a matter of routine 

design choice.

J.A. 533, at ¶¶ 116-17 (internal citations omitted). Apple 

supports its expert testimony by citing to a textbook 

offered by Dr. Elliott, Slot Speaker’s expert, explaining

the different effects of loudspeaker cabinet shapes on 
SLOT SPEAKER TECHNOLOGIES v. APPLE INC. 21

sound diffraction. The textbook explains that the relative 

effects of straight and curved walls in loudspeakers were 

well known in the art. There is, moreover, no evidence to 

suggest that a person of ordinary skill in the art would 

not have been familiar with the costs and benefits of these

well-known design choices. 

For these reasons, we conclude that the Board erred 

when it found that the combination of Tomonori and 

Sadaie did not render claim 3 obvious. 

IV. CONCLUSION

For the foregoing reasons, we affirm in part and reverse in part the Board’s judgment.

AFFIRMED IN PART, REVERSED IN PART

COSTS

Costs to Apple.