                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

NAOMI WALTON,                                No. 05-17308
                 Plaintiff-Appellant,           D.C. No.
                 v.                          CV-03-01460-SI
U.S. MARSHALS SERVICE; MARC A.                  ORDER
FARMER, Chief, Judicial Protective            AMENDING
Services-Judicial Security                   OPINION AND
Division; U.S. DEPARTMENT OF                  DENYING
HEALTH AND HUMAN SERVICES;                   PETITION FOR
BENIGNO G. REYNA, Director,                 REHEARING AND
United States Marshals Service;              PETITION FOR
ALBERTO R. GONZALES, Attorney                 REHEARING
General,                                     EN BANC AND
             Defendants-Appellees.             AMENDED
                                               OPINION

        Appeal from the United States District Court
           for the Northern District of California
       Susan Yvonne Illston, District Judge, Presiding

                 Argued and Submitted
           November 16, 2006—Portland, Oregon

                   Filed February 9, 2007
                   Amended June 26, 2007

    Before: Alfred T. Goodwin, Raymond C. Fisher, and
            Milan D. Smith, Jr., Circuit Judges.

            Opinion by Judge Milan D. Smith, Jr.




                             7643
              WALTON v. U.S. MARSHALS SERVICE           7647


                        COUNSEL

Edith J. Benay, San Francisco, California, for the plaintiff-
appellant.

Eric Fleisig-Greene, United States Department of Justice,
Washington, DC, for the defendant-appellee.


                          ORDER

  The opinion filed on February 9, 2007 and published at 476
F.3d 723 is hereby AMENDED as follows:

  On 476 F.3d at 731, following the heading reading “3.
Localizing Sound” replace:
7648             WALTON v. U.S. MARSHALS SERVICE
<< Walton further alleges that the USMS regarded her as
disabled in the major life activity of localizing sound. We
decline to consider whether localizing sound could be an
additional major life activity because Walton failed to raise
this argument before the district court. See Head v. Glacier
Nw., Inc., 413 F.3d 1053, 1060 n.19 (9th Cir. 2005). >>

with:

<< Walton also alleges that the USMS regarded her as dis-
abled because it regarded her as substantially limited in the
activity of localizing sound.1 In order to show that such a limi-
tation is a disability within the meaning of the Acts, Walton
must provide evidence that the ability to localize sound quali-
fies as a major life activity. See Coons, 383 F.3d at 885. We
find that she has not.

   “ ‘Major life activities’ . . . refers to those activities that are
of central importance to daily life.” Williams, 534 U.S. at 197;
see also Fraser v. Goodale, 342 F.3d 1032, 1039 (9th Cir.
2003) (quoting Bragdon v. Abbott, 524 U.S. 624, 638 (1998)).
To determine whether a proposed activity is a major life activ-
ity, we begin with the illustrative list in the implementing reg-
ulations which describes major life activities as “functions
such as caring for one’s self, performing manual tasks, walk-
ing, seeing, hearing, speaking, breathing, learning, and work-
ing.” Bragdon, 524 U.S. at 638 (quoting 45 C.F.R.
§ 84.3(j)(2)(ii) (1997) and 28 C.F.R. § 41.31(b)(2) (1997)).
Because “[t]he plain meaning of the word ‘major’ denotes
comparative importance,” we then compare the proposed
  1
    Walton raised this argument in a supplemental brief filed with the dis-
trict court after the close of briefing on USMS’s motion for summary
judgment. The district court indicated that it received and considered Wal-
ton’s supplemental brief, but its order did not address Walton’s additional
argument. We consider it here. We observe that we may affirm the district
court’s grant of summary judgment on any ground supported by the
record. Miranda v. City of Cornelius, 429 F.3d 858, 860 n.1 (9th Cir.
2005).
               WALTON v. U.S. MARSHALS SERVICE              7649
activity with the major life activities enumerated in the regu-
lations, noting that “the touchstone for determining an activi-
ty’s inclusion under the statutory rubric is its significance.”
Id. (quoting Abbott v. Bragdon, 107 F.3d 934, 939-40 (1st Cir.
1997)) (internal quotation marks omitted).

   The “comparative importance” standard requires that a pro-
posed activity must be of comparable significance as an enu-
merated major life activity in order to qualify as a major life
activity. For example, in Bragdon, the Supreme Court held
that “reproduction [is] a major life activity, since reproduction
could not be regarded as any less important than working and
learning.” 524 U.S. at 639. See also Sinkler v. Midwest Prop.
Mgmt. Ltd. P’ship, 209 F.3d 678, 684-85 (7th Cir. 2000)
(“getting to and from work” is not of equal significance to
enumerated major life activities and thus is not a major life
activity; “rather . . . [it] is a sub-species of the activity of
‘working’ or of ‘driving’ ”).

   Walton provides no authority for her argument that the
ability to localize sound is a major life activity. Instead, she
claims that under our decision in Head v. Glacier Northwest
Inc., 413 F.3d 1053 (9th Cir. 2005), her experts’ reports dis-
cussing the impact of the inability to localize sound on an
individual’s hearing should be considered evidence of com-
parative importance. Walton misreads Head. Head does not
stand for the proposition that a proposed activity is a major
life activity simply because it is “in some instances” neces-
sary to the performance of an established major life activity.
Such an expansive reading of “major life activity” would col-
lapse into one the final two of the following three inquiries to
determine the existence of a disability under our case law:
“(1) we determine whether [the alleged impairment] is a phys-
ical impairment, (2) we identify the life activity on which
[plaintiff] relies, and we determine whether this activity is a
major life activity, and (3) we determine whether the impair-
ment substantially limits the major life activity.” Fraser, 342
7650           WALTON v. U.S. MARSHALS SERVICE
F.3d at 1038. As the Second Circuit explained in Reeves v.
Johnson Controls World Services, Inc.:

    An ADA plaintiff could considerably lessen the bur-
    den of making an individualized showing of a sub-
    stantial limitation were he able to define the major
    life activity as narrowly as possible, with an eye
    toward conforming the definition to the particular
    facts of his own case. . . . Narrowing and diluting the
    definition of a major life activity, which in turn
    might lessen the plaintiff’s burden of proving a sub-
    stantial limitation, would undermine the role of the
    statute’s “substantial limit[ation]” inquiry in ensur-
    ing that only impairments of some significance are
    protected by the ADA.

140 F.3d 144, 152 (2d Cir. 1988). Thus, consistent with con-
trolling precedent, our observation in Head that a proposed
activity may be important because it “is necessary in many
instances to perform” an enumerated major life activity does
not obviate the need to meet the ultimate standard that a pro-
posed activity must be “of comparative importance, and . . .
central to most people’s daily lives” in order to be considered
a major life activity. Head, 413 F.3d at 1062.

   Under the proper standard, the evidence in the record is
insufficient to support Walton’s assertion that the ability to
localize sound is itself a major life activity. For the reasons
discussed in the preceding section, we do not give any eviden-
tiary weight to Dr. Sweetow’s report. Walton’s only other
expert report is that authored by Dr. Cook. In the light most
favorable to Walton, Dr. Cook’s report indicates that a com-
plete inability to localize sound may severely impact how
hearing is used in daily life. Dr. Cook’s report does not, how-
ever, suggest that the ability to localize sound is comparable
to “caring for one’s self, performing manual tasks, walking,
seeing, hearing, speaking, breathing, learning, and working”
or that the ability to localize sound is itself central to an indi-
              WALTON v. U.S. MARSHALS SERVICE             7651
vidual’s life. Thus, on this record, we are unable to conclude
that auditory localization is of comparative importance to the
enumerated major life activities, and Walton therefore cannot
sustain a claim that she was regarded as disabled because of
her inability to localize sound. >>

   With this amendment, the panel has voted to deny Appel-
lant Naomi Walton’s petition for rehearing. Judges Fisher and
Smith have voted to deny the suggestion for rehearing en
banc, and Judge Goodwin has recommended denying the sug-
gestion for rehearing en banc.

  The full court has been advised of the petition for rehearing
en banc, and no judge of the court has requested a vote on it.
Fed. R. App. P. 35.

  The petition for rehearing and petition for rehearing en
banc are DENIED.

  Pursuant to General Order 5.3(a), subsequent petitions for
rehearing or rehearing en banc may be filed concerning this
amendment.

  IT IS SO ORDERED.


                         OPINION

MILAN D. SMITH, JR., Circuit Judge:

   Naomi Walton sued the U.S. Marshals Service (“USMS”)
under the Rehabilitation Act of 1973 alleging that the USMS
unlawfully discharged her because of her hearing impairment.
She appeals from the district court’s grant of summary judg-
ment in favor of the USMS, arguing that the district court
erred in ruling that she failed to demonstrate a genuine issue
of material fact concerning whether she was disabled within
7652             WALTON v. U.S. MARSHALS SERVICE
the meaning of the Acts.1 We have jurisdiction under 28
U.S.C. § 1291, and we affirm.

                          I.   Background

   Walton was employed by Akal Security, Inc. (“Akal”) as a
Court Security Officer (“CSO”) at the United States District
Court for the Northern District of California. Akal is a private
contractor that provides CSOs at federal courthouses within
the Ninth Circuit by contract with the USMS. The contract
requires that Akal employees for CSO positions meet certain
USMS physical requirements. Based on the USMS’s determi-
nation that Walton did not meet the USMS’s audiological
standards, the USMS medically disqualified her from employ-
ment as a CSO and Akal terminated her employment.

   In its agreement with Akal, the USMS requires CSOs to
undergo annual physical examinations. The USMS’s current
CSO audiological standards were developed based upon a
study by Dr. Richard Miller, Director of Law Enforcement
Medical Programs for the Office of Federal Occupational
Health. Dr. Miller’s study identified twenty-nine job functions
essential to the CSO position, one of which is the ability to
determine the location and source of sound. The Judicial Con-
ference of the United States adopted the conclusions of Dr.
Miller’s study and directed the USMS to implement a number
of changes to the CSO medical standards.

  In November 2001, as a part of an annual physical exami-
nation required by her employment contract, Walton under-
went audiological testing by an Akal-designated physician.
Dr. Louis Chelton, a medical review officer in the Office of
  1
   Because “[t]he standards used to determine whether an act of discrimi-
nation violated the Rehabilitation Act are the same standards applied
under the Americans with Disabilities Act,” we refer to them jointly as
“the Acts.” Coons v. Sec’y of the U.S. Dep’t of the Treasury, 383 F.3d
879, 884 (9th Cir. 2004).
              WALTON v. U.S. MARSHALS SERVICE                7653
Federal Occupational Health, reviewed the results of Walton’s
test in order to assess her compliance with USMS standards.
Based on Walton’s test results, Dr. Chelton noted that Walton
has a disparity between her two ears’ ability to detect sound,
and that this disparity impacts her ability to localize sound.

   Consistent with USMS policy, Walton was given an oppor-
tunity to provide further test results or other information to
support her qualification before the USMS made a final rec-
ommendation concerning her medical eligibility. Walton took
this opportunity and underwent a second hearing test. Dr.
Chelton reviewed the additional results and reported on a
“Medical Review Form” that Walton was “[n]ot medically
qualified to perform the essential functions of the job.” The
form reads, in relevant part:

    The following medical condition(s) poses a signifi-
    cant risk to the health and safety of yourself and/or
    others in the performance of essential job functions.
    Medical follow-up, if requested, and any reduction
    of duties are listed below. Send medical information
    to your employer.

    You have a significant hearing impairment according
    to the results of the tests provided by you from
    Gould Medical Foundation. According to the test
    results you have only one functioning ear. With only
    one functioning ear, you are unable to localize the
    direction of sound, an essential job function. Hearing
    aids may malfunction or become dislodged in critical
    situations. Your job requires the ability to detect
    where sound is coming from. Your inability to do so
    poses a significant risk to the health and safety of
    yourself, other law enforcement officers, and the
    public.

The USMS then notified Akal of Walton’s disqualification,
and Akal terminated Walton’s employment.
7654             WALTON v. U.S. MARSHALS SERVICE
   In her Third Amended Complaint, Walton alleged that the
USMS and various individuals and federal agencies termi-
nated her employment in violation of the Rehabilitation Act,
29 U.S.C. § 701-796l, and, in the alternative, the Administra-
tive Procedure Act, 5 U.S.C. § 701-706. The district court
held that the USMS was a proper defendant under the Reha-
bilitation Act2 and granted the USMS’s motion for summary
judgment on Walton’s Rehabilitation Act claims, finding that
Walton did not make a prima facie showing that she was dis-
abled under the meaning of the Acts. Walton filed a timely
appeal of the district court’s decision.

                     II.   Standard of Review

  We review a district court’s grant of summary judgment on
a Rehabilitation Act claim de novo. Coons v. Sec’y of the U.S.
Dep’t of the Treasury, 383 F.3d 879, 884 (9th Cir. 2004).
“Viewing the evidence in the light most favorable to the non-
moving party, and drawing all reasonable inferences in her
favor, we must determine whether the district court correctly
applied the relevant substantive law and whether there are any
genuine issues of material fact.” Id. (quoting Brown v. Lucky
Stores, Inc., 246 F.3d 1182, 1187 (9th Cir. 2001)).

                           III.   Discussion

   To state a prima facie case under the Rehabilitation Act, a
plaintiff must demonstrate that (1) she is a person with a dis-
ability, (2) who is otherwise qualified for employment, and
(3) suffered discrimination because of her disability. See
Wong v. Regents of the Univ. of Cal., 410 F.3d 1052, 1058
(9th Cir. 2005). The Americans with Disabilities Act, whose
standards of substantive liability are incorporated in the Reha-
bilitation Act, defines “disability” as: (A) a physical or mental
impairment that substantially limits one or more of the major
  2
    The district court’s decision that the USMS is a proper defendant in
this case is not before this court and we express no opinion on the issue.
                  WALTON v. U.S. MARSHALS SERVICE                     7655
life activities of such individual, (B) a record of such an
impairment, or (C) being regarded as having such an impair-
ment. 42 U.S.C. §12102(2); Coons, 383 F.3d at 884.

                   A.    “Regarded As” Disabled

   [1] Walton does not allege that she is actually disabled;
rather she alleges that she is a person with a disability within
the meaning of the Acts because she was “regarded as” dis-
abled. The Equal Employment Opportunity Commission’s
regulations state that an individual who is “regarded as” dis-
abled:

      (1) Has a physical or mental impairment that does
      not substantially limit major life activities but is
      treated by a covered entity as constituting such limi-
      tation;

      (2) Has a physical or mental impairment that sub-
      stantially limits major life activities only as a result
      of the attitudes of others toward such impairment; or

      (3) Has none of the impairments defined in para-
      graph (h) (1) or (2) of this section3 but is treated by
      a covered entity as having a substantially limiting
      impairment.
  3
   The regulations define “Physical or mental impairment” as:
      (1) Any physiological disorder, or condition, cosmetic disfigure-
      ment, or anatomical loss affecting one or more of the following
      body systems: neurological, musculoskeletal, special sense
      organs, respiratory (including speech organs), cardiovascular,
      reproductive, digestive, genito-urinary, hemic and lymphatic,
      skin, and endocrine; or
      (2) Any mental or psychological disorder, such as mental retar-
      dation, organic brain syndrome, emotional or mental illness, and
      specific learning disabilities.
29 C.F.R. § 1630.2(h).
7656           WALTON v. U.S. MARSHALS SERVICE
29 C.F.R. § 1630.2(l). Assuming without deciding that the
EEOC regulations are valid, the Supreme Court in Sutton v.
United Air Lines, Inc., 527 U.S. 471 (1999), held that an
employee may be “regarded as” disabled in one of two ways:

    (1) a covered entity mistakenly believes that a per-
    son has a physical impairment that substantially lim-
    its one or more major life activities, or

    (2) a covered entity mistakenly believes that an
    actual, nonlimiting impairment substantially limits
    one or more major life activities.

527 U.S. at 489. The Supreme Court in Sutton further
instructed that: “In both cases, it is necessary that a covered
entity entertain misperceptions about the individual —it must
believe either that one has a substantially limiting impairment
that one does not have or that one has a substantially limiting
impairment when, in fact, the impairment is not so limiting.”
Id.

   [2] Following Sutton, this court requires that a plaintiff
alleging a “regarded as” claim provide evidence of the
employer’s “misperception,” or subjective belief that the
plaintiff is substantially impaired. See, e.g., EEOC v. United
Parcel Service, Inc., 306 F.3d 794, 805 (9th Cir. 2002). In
EEOC, we noted the importance of the “employer’s motiva-
tion[s]” and held that the district court “made no finding about
what UPS actually regarded as the restriction, real or unreal,
in claimants’ vision that substantially limits all of them in the
major life activity of seeing.” Id. (emphasis in original). Simi-
larly, in Murphy v. United Parcel Service, Inc., 527 U.S. 516
(1999), the Supreme Court emphasized that a plaintiff must
show that her employer regards her as substantially limited in
a major life activity and not just unable to meet a particular
job performance standard. See id. at 524.

  [3] A plaintiff need not make this showing—that an
employer subjectively believed that the plaintiff is substan-
               WALTON v. U.S. MARSHALS SERVICE               7657
tially limited in a major life activity as the result of an
impairment—through direct evidence. Johnson v. Paradise
Valley Unified Sch. Dist., 251 F.3d 1222, 1229 n.6 (9th Cir.
2001). However, because “a person cannot be regarded as
disabled unless the deficiency that the person is regarded as
having is a disability,” an employee who is only able to show
that her employer regarded her as impaired must also provide
evidence that the imputed impairment is objectively substan-
tially limiting. See EEOC, 306 F.3d at 801 (emphasis in origi-
nal). See also Thompson v. Holy Family, 121 F.3d 537, 540-
41 (9th Cir. 1997) (defendant’s belief that plaintiff was inca-
pable of lifting 25 pounds is insufficient evidence that the
defendant regarded plaintiff as disabled because the court
“noted previously that a 25-pound restriction does not amount
to a substantial limitation on the ability to lift”).

   [4] Accordingly, we hold that in order to state a “regarded
as” claim a plaintiff must establish that the employer believes
that the plaintiff has some impairment, and provide evidence
that the employer subjectively believes that the plaintiff is
substantially limited in a major life activity. If the plaintiff
does not have direct evidence of the employer’s subjective
belief that the plaintiff is substantially limited in a major life
activity, the plaintiff must further provide evidence that the
impairment imputed to the plaintiff is, objectively, a substan-
tially limiting impairment. See Thornton v. McClatchy News-
papers, Inc., 261 F.3d 789, 798 (9th Cir. 2001) (affirming
district court’s judgment for defendant on plaintiff’s “re-
garded as” claim because “there is no specific evidence that
[employer] viewed her as substantially limited” and “[em-
ployee’s] restrictions did not rise to the level of substantial
limitation”).

   Walton alleges that she was regarded as substantially lim-
ited in the major life activities of (1) hearing, (2) working, and
(3) localizing sound. Walton fails to raise a genuine issue of
material fact that the USMS regarded her as disabled with
respect to any of these activities.
7658               WALTON v. U.S. MARSHALS SERVICE
    1.        The Major Life Activity of Hearing

   According to EEOC regulations, hearing is a major life
activity. 29 C.F.R. § 1630.2(i). The district court found that
Walton did not raise a genuine issue of material fact that the
USMS subjectively believed her hearing to be substantially
limited, or that the inability to localize sound is an objective
and substantial limitation on the major life activity of hearing.
We agree.

         a.     Subjective Belief of Substantial Limitation

   [5] A substantial limitation on the major life activity of
hearing is a severe restriction on the use of an individual’s
hearing compared to how unimpaired individuals normally
use their hearing in daily life. See Toyota Motor Mfg., Ky, Inc.
v. Williams, 534 U.S. 184, 200-01 (2002) (stating the rule in
terms of the major life activity of performing manual tasks);
EEOC, 306 F.3d at 802 (same regarding the major life activity
of seeing). Walton primarily argues that Dr. Chelton’s report
disqualifying her from employment as a CSO raises a genuine
issue of material fact that the USMS believed she was sub-
stantially limited in the major life activity of hearing.

   [6] Walton’s argument that her disqualification under the
USMS’s hearing standards is itself sufficient evidence that the
USMS regarded her as disabled in a major life activity fails.
In EEOC, we held that an allegation that an employer which
requires its employees to meet certain vision standards does
not establish a claim that the employer regards one who fails
to meet the vision requirement as being substantially limited
in the major life activities of working or seeing. 306 F.3d at
804 (citing Sutton, 527 U.S. at 490). Standing alone, Walton’s
failure to meet the USMS hearing standards does not raise a
genuine issue of material fact that the USMS regarded her as
disabled.

   [7] The statements in Dr. Chelton’s report are also insuffi-
cient to constitute direct evidence of the USMS’s subjective
               WALTON v. U.S. MARSHALS SERVICE                7659
belief that Walton was substantially limited in the major life
activity of hearing. Construed in the light most favorable to
Walton, Dr. Chelton’s statements that: “you are unable to
localize sound,” “you have only one functioning ear,” and
“[y]our inability to [localize sound] poses a significant risk to
the health and safety of yourself, other law enforcement offi-
cers and the public,” is evidence of his belief that Walton
could not safely perform her job. However, because Dr. Chel-
ton’s letter does not express an opinion on whether the USMS
regarded Walton’s hearing impairment as substantially limit-
ing in a major life activity, it does not follow that the USMS
regarded her as disabled. See EEOC, 306 F.3d at 806 (citing
Thompson, 121 F.3d at 541).

       b.   Objective Substantial Limitations

   [8] Since Walton failed to provide direct evidence that
USMS regarded her as substantially limited in a major life
activity because of her hearing impairment, Walton must
show that the inability to localize sound is an impairment that
substantially limits the major life activity of hearing. Thomp-
son, 121 F.3d at 541 (“[a]s with real impairments, . . . a per-
ceived impairment must be substantially limiting and
significant”). Attempting to make this showing, Walton relies
on a report by her expert, Dr. Robert Sweetow, and on a
report by Dr. Lynn Cook, a consulting audiologist in the
development of the USMS hearing standards.

   [9] Walton argues that the following paragraph in Dr.
Sweetow’s expert report raises a genuine issue of material
fact that the inability to localize sound is an impairment that
substantially limits the major life activity of hearing:

    Dr. Chelton states the plaintiff is “unable to localize
    the direction of sound.” The ability to localize sound
    is ”. . . essential to the condition or manner under
    which an individuals [sic] can . . .” use the sense of
    hearing. Thus being able to localize sound severely/
7660           WALTON v. U.S. MARSHALS SERVICE
    significantly restricts one’s hearing as compared to
    how unimpaired people normally hear in everyday
    life.

(Ellipses in original). This paragraph is insufficient to raise a
genuine issue of material fact. In this circuit, “[e]xpert opin-
ion is admissible and may defeat summary judgment if it
appears the affiant is competent to give an expert opinion and
the factual basis for the opinion is stated in the affidavit, even
though the underlying factual details and reasoning upon
which the opinion is based are not.” Bulthuis v. Rexall Corp.,
789 F.2d 1315, 1318 (9th Cir. 1985) (per curiam). Dr. Swee-
tow does not state a factual basis for his opinion; the conclu-
sion appears to be drawn from the second sentence, but the
second sentence references no facts and instead contains an
unattributed quote. Dr. Sweetow’s conclusory report fails to
raise a genuine issue of material fact that the inability to local-
ize sound is an impairment that substantially limits the major
life activity of hearing. See also Broussard v. Univ. of Cal.,
at Berkeley, 192 F.3d 1252, 1258-59 (9th Cir. 1999) (finding
report by plaintiff’s vocational rehabilitation specialist that
“did not compare the jobs [plaintiff] could do before and after
the onset of her [disability],” and did not identify the “time
periods he was analyzing” to be “the type of conclusory alle-
gation which this court found insufficient to withstand the
motion for summary judgment in Thompson”).

   Walton’s only other evidence that the inability to localize
sound is substantially limiting is a draft report prepared by Dr.
Lynn Cook for the United States Immigration and Naturaliza-
tion Service. In a section titled “Why is Auditory Localization
Important?” Cook states that auditory localization is neces-
sary for the performance of certain activities. Viewed in the
light most favorable to Walton, Dr. Cook’s report indicates
that, unlike a mere difficulty with localizing sound, a com-
plete inability to localize sound may severely impact how
hearing is used in daily life by precluding activities such as
locating other people, pinpointing the direction of a sound of
               WALTON v. U.S. MARSHALS SERVICE              7661
interest, and identifying if footsteps are retreating or
approaching.

   However, Dr. Cook’s report also discusses compensatory
measures, which “must be taken into account in judging
whether an individual possesses a disability.” Albertson’s,
Inc. v. Kirkingburg, 527 U.S. 555, 565 (1999) (citing Sutton,
527 U.S. at 482). In stating that “visual localization is gener-
ally just as accurate” as auditory localization, Dr. Cook’s
report opines that the compensatory measure of “visual local-
ization” mitigates the effects of an inability to localize sound.
Since there is “no principled basis for distinguishing between
[mitigating] measures undertaken with artificial aids, like
medications and devices, and measures undertaken, whether
consciously or not, with the body’s own systems,” Albert-
son’s, 527 U.S. at 565-66, we view the inability to localize
sound as being mitigated by visual localization.

   [10] Dr. Cook’s report states the only disadvantages of
relying on visual localization apparent from the record and
Walton does not provide any further evidence on this issue.
Dr. Cook states that mitigating the effects of the inability to
localize sound with visual localization has only minor draw-
backs: it “is not nearly as efficient (quick) as auditory local-
ization” and it “assumes that the source of the sound can be
visualized, which is often not possible in low-light environ-
ments, when the source is visually obscured by other objects,
or when the source is not visually apparent (as in the bank of
radios above).” Walton relies solely on Dr. Cook’s report, and
presents no contrary evidence in the record that auditory
localization, as mitigated by visual localization, is an objec-
tively severe restriction on the use of an individual’s hearing
compared to how unimpaired individuals normally use their
hearing in daily life. On this basis, no reasonable trier of fact
could find that the inability to localize sound, as characterized
here, is in fact substantially limiting.

   [11] Walton has not raised a genuine issue of material fact
that the impairment imputed to her is in fact substantially lim-
7662           WALTON v. U.S. MARSHALS SERVICE
iting, and we therefore affirm the district court’s finding that
Walton was not regarded as disabled with respect to the major
life activity of hearing.

    2.   Working

   [12] EEOC regulations specify that a person is “substan-
tially limited” in the major life activity of working if she is
“significantly restricted in the ability to perform either a class
of jobs or a broad range of jobs in various classes as com-
pared to the average person having comparable training, skills
and abilities.” 29 C.F.R. § 1630.2(j)(3)(i). An allegation that
the employer regards the impairment as precluding the
employee from a single, particular position is insufficient to
support a claim that the employer regards the employee as
having a substantially limiting impairment. See Murphy, 527
U.S. at 523.

   [13] Walton raises insufficient evidence to support her
argument that the USMS regarded her as substantially limited
in the major life activity of working. In Thornton, we held
that a plaintiff alleging substantial limitation in the major life
activity of working “must present specific evidence about rel-
evant labor markets to defeat summary judgment” and “iden-
tify what requirements posed by the class of . . . jobs . . . were
problematic in light of the limitations imposed on her.” 261
F.3d at 795-96 (citation omitted) (ellipses in original). Walton
does not meet the evidentiary standard set out in Thornton
because she relies solely on Dr. Chelton’s letter, Dr. Swee-
tow’s expert report and Dr. Cook’s report on auditory local-
ization, none of which expresses any opinion about relevant
labor markets or Walton’s particular training, knowledge,
skills or abilities. Accordingly, we affirm the district court’s
holding that Walton failed to raise a genuine issue of material
fact that she was substantially limited in the major life activity
of working.
                 WALTON v. U.S. MARSHALS SERVICE                     7663
      3.   Localizing Sound

   Walton also alleges that the USMS regarded her as disabled
because it regarded her as substantially limited in the activity
of localizing sound.4 In order to show that such a limitation
is a disability within the meaning of the Acts, Walton must
provide evidence that the ability to localize sound qualifies as
a major life activity. See Coons, 383 F.3d at 885. We find that
she has not.

   “ ‘Major life activities’ . . . refers to those activities that are
of central importance to daily life.” Williams, 534 U.S. at 197;
see also Fraser v. Goodale, 342 F.3d 1032, 1039 (9th Cir.
2003) (quoting Bragdon v. Abbott, 524 U.S. 624, 638 (1998)).
To determine whether a proposed activity is a major life activ-
ity, we begin with the illustrative list in the implementing reg-
ulations which describes major life activities as “functions
such as caring for one’s self, performing manual tasks, walk-
ing, seeing, hearing, speaking, breathing, learning, and work-
ing.” Bragdon, 524 U.S. at 638 (quoting 45 C.F.R.
§ 84.3(j)(2)(ii) (1997) and 28 C.F.R. § 41.31(b)(2) (1997)).
Because “[t]he plain meaning of the word ‘major’ denotes
comparative importance,” we then compare the proposed
activity with the major life activities enumerated in the regu-
lations, noting that “the touchstone for determining an activi-
ty’s inclusion under the statutory rubric is its significance.”
Id. (quoting Abbott v. Bragdon, 107 F.3d 934, 939-40 (1st Cir.
1997)) (internal quotation marks omitted).
  4
    Walton raised this argument in a supplemental brief filed with the dis-
trict court after the close of briefing on USMS’s motion for summary
judgment. The district court indicated that it received and considered Wal-
ton’s supplemental brief, but its order did not address Walton’s additional
argument. We consider it here. We observe that we may affirm the district
court’s grant of summary judgment on any ground supported by the
record. Miranda v. City of Cornelius, 429 F.3d 858, 860 n.1 (9th Cir.
2005).
7664           WALTON v. U.S. MARSHALS SERVICE
   The “comparative importance” standard requires that a pro-
posed activity must be of comparable significance as an enu-
merated major life activity in order to qualify as a major life
activity. For example, in Bragdon, the Supreme Court held
that “reproduction [is] a major life activity, since reproduction
could not be regarded as any less important than working and
learning.” 524 U.S. at 639. See also Sinkler v. Midwest Prop.
Mgmt. Ltd. P’ship, 209 F.3d 678, 684-85 (7th Cir. 2000)
(“getting to and from work” is not of equal significance to
enumerated major life activities and thus is not a major life
activity; “rather . . . [it] is a sub-species of the activity of
‘working’ or of ‘driving’ ”).

   Walton provides no authority for her argument that the
ability to localize sound is a major life activity. Instead, she
claims that under our decision in Head v. Glacier Northwest
Inc., 413 F.3d 1053 (9th Cir. 2005), her experts’ reports dis-
cussing the impact of the inability to localize sound on an
individual’s hearing should be considered evidence of com-
parative importance. Walton misreads Head. Head does not
stand for the proposition that a proposed activity is a major
life activity simply because it is “in some instances” neces-
sary to the performance of an established major life activity.
Such an expansive reading of “major life activity” would col-
lapse into one the final two of the following three inquiries to
determine the existence of a disability under our case law:
“(1) we determine whether [the alleged impairment] is a phys-
ical impairment, (2) we identify the life activity on which
[plaintiff] relies, and we determine whether this activity is a
major life activity, and (3) we determine whether the impair-
ment substantially limits the major life activity.” Fraser, 342
F.3d at 1038. As the Second Circuit explained in Reeves v.
Johnson Controls World Services, Inc.:

    An ADA plaintiff could considerably lessen the bur-
    den of making an individualized showing of a sub-
    stantial limitation were he able to define the major
    life activity as narrowly as possible, with an eye
               WALTON v. U.S. MARSHALS SERVICE                7665
    toward conforming the definition to the particular
    facts of his own case. . . . Narrowing and diluting the
    definition of a major life activity, which in turn
    might lessen the plaintiff’s burden of proving a sub-
    stantial limitation, would undermine the role of the
    statute’s “substantial limit[ation]” inquiry in ensur-
    ing that only impairments of some significance are
    protected by the ADA.

140 F.3d 144, 152 (2d Cir. 1988). Thus, consistent with con-
trolling precedent, our observation in Head that a proposed
activity may be important because it “is necessary in many
instances to perform” an enumerated major life activity does
not obviate the need to meet the ultimate standard that a pro-
posed activity must be “of comparative importance, and . . .
central to most people’s daily lives” in order to be considered
a major life activity. Head, 413 F.3d at 1062.

   [14] Under the proper standard, the evidence in the record
is insufficient to support Walton’s assertion that the ability to
localize sound is itself a major life activity. For the reasons
discussed in the preceding section, we do not give any eviden-
tiary weight to Dr. Sweetow’s report. Walton’s only other
expert report is that authored by Dr. Cook. In the light most
favorable to Walton, Dr. Cook’s report indicates that a com-
plete inability to localize sound may severely impact how
hearing is used in daily life. Dr. Cook’s report does not, how-
ever, suggest that the ability to localize sound is comparable
to “caring for one’s self, performing manual tasks, walking,
seeing, hearing, speaking, breathing, learning, and working”
or that the ability to localize sound is itself central to an indi-
vidual’s life. Thus, on this record, we are unable to conclude
that auditory localization is of comparative importance to the
enumerated major life activities, and Walton therefore cannot
sustain a claim that she was regarded as disabled because of
her inability to localize sound.
7666          WALTON v. U.S. MARSHALS SERVICE
                B.      Record of Impairment

   [15] Walton also alleges that she is disabled on the basis of
having a record of impairment as defined in 42 U.S.C.
§ 12102(2)(B). Implementing regulations explain that having
a “record” of a disability means either having a history of, or
having been misclassified as having, a substantially limiting
impairment. 29 C.F.R. § 1630.2(k). See also Coons, 383 F.3d
at 886 (doctor’s letter describing stress-related physical ail-
ments did not constitute such a record because none of the
treated impairments substantially limited any major life activ-
ity); Bailey v. Georgia-Pacific Corp., 306 F.3d 1162, 1169
(1st Cir. 2002) (plaintiff’s long and documented record of
alcoholism did not establish a disability because the record
did not show that plaintiff’s alcoholism “significantly inter-
fered with a major life activity”).

   [16] Walton argues that Dr. Chelton’s two reports regard-
ing her USMS test results constitute a medical record of hav-
ing only one functioning ear and being unable to localize
sound. For the reasons stated above, Walton has failed to raise
a genuine issue of material fact that this impairment is a sub-
stantially limiting impairment; thus, any record of this impair-
ment would not meet the requirements of 29 C.F.R.
§ 1630.2(k).

                   C.    Remaining Claims

  [17] Because Walton is not a person with a disability as
defined by the Acts, Walton’s claims that the USMS discrimi-
nated against her based on disability fail as a matter of law.
See Coons, 383 F.3d at 886. We therefore affirm the district
court’s decision to grant summary judgment in favor of the
USMS on Walton’s remaining claims.

                        IV.   Conclusion

  We conclude that Walton cannot demonstrate she is dis-
abled within the meaning of the Acts, and we affirm the dis-
             WALTON v. U.S. MARSHALS SERVICE           7667
trict court’s grant of summary judgment to the USMS.

  AFFIRMED.
