This is a consolidated appeal from the trial court's vacatur of orders entered by the Labor and Industry Review Commission in three worker's compensation claims, and its remand to the Commission for further proceedings.
The issue here is whether an employer is liable for all of an employee's compensable hearing loss even though only part of that loss was caused by the employer. The Commission's position is that under § 102.555(8), Stats., the employer is liable for all of an employee's compensable hearing loss, including any pre-employment hearing loss as long as that pre-employment hearing loss was below the compensable threshold, but that the employer is not liable for the pre-employment hearing loss if that loss equaled or exceeded the compensable threshold. Hamischfeger, on the other hand, contends that the employer is only liable if the hearing loss caused by the employment exceeds thirty decibels. The trial court held that the Commission violated § 102.555(8), Stats. Although we reject Harnischfeger's interpretation, we affirm the trial court's orders.1
I.
The three cases before us, to which the Commission applied its interpretation of § 102.555(8), STATS., *231are those of Guenther Gieske, Edward Bohn, and Emmerich Drawitsch. Gieske worked for Harnischfe-ger from 1967 through June 3,1989. The parties agree that he suffered compensable hearing loss during this employment. In awarding hearing-loss compensation to Gieske, the Commission did not give to Harnischfe-ger credit for Gieske's pre-employment hearing loss because that loss did not, by itself, rise to a compensa-ble level. As explained in the decision by the Administrative Law Judge, adopted by the Commission, the Department of Industry, Labor and Human Relations' "policy has been not to allow a credit unless a pre-existing hearing loss rises to the compensable level."
Bohn worked for Harnischfeger from 1965 through September 5, 1989. The Commission similarly did not credit Harnischfeger for Bohn's pre-employment hearing loss because that loss did not, by itself, rise to a compensable level. Drawitsch worked for Harnischfe-ger from 1965 through February 2, 1990. As in Gieske and Bohn, the Commission did not grant to Harnischfe-ger credit for Drawitsch's pre-employment hearing loss because that loss did not, by itself, rise to a compensa-ble level.
II.
As material here, § 102.555(8), STATS., provides that "[a]n employer is liable for the entire occupational deafness to which his or her employment has contributed; but if previous deafness is established by a hearing test or other competent evidence . . . the employer is not liable for previous loss so established."2 " 'Occupational deafness' means permanent partial or *232permanent total loss of hearing of one or both ears due to prolonged exposure to noise in employment." Section 102.555(1), Stats.
Under rules not challenged here, the Department of Industry Labor and Human Relations bases measurement of hearing loss on "the average of the 4 speech frequencies," and has determined that "[a]udiometric measurement for these 4 frequencies averaging 30 decibels or less on the ANSI calibration does not constitute any practical hearing impairment." WlS. Adm. Code § Ind. 80.25(4). Accordingly, hearing loss must exceed 30 decibels to be compensable. WlS. Adm. Code § Ind. 80.25(8).
Judicial review of the Commission's orders is limited. Section 102.23, Stats. In the context of this case, the Commission's orders may not be set aside unless the Commission "acted without or in excess of its powers." Section 102.23(1)(e)1, Stats. The trial court determined that the Commission's orders violated § 102.555(8), STATS. Although our review is de novo, see Stafford Trucking, Inc. v. ILHR Dept., 102 Wis. 2d 256, 260, 306 N.W.2d 79, 82 (Ct. App. 1981), we agree.
"Absent a constitutional infirmity, courts must apply statutes as they are written, unless to do so would lead to an absurd result that did not reflect the legislature's intent." State v. Young, 180 Wis. 2d 700, 704, 511 N.W.2d 309, 311 (Ct. App. 1993), review *233granted, February 22, 1994. Policy considerations in worker's compensation matters are for the legislature and not the courts. State v. Labor and Industry Review Commission, 136 Wis. 2d 281, 297, 401 N.W.2d 585, 592 (1987). Although courts rightfully give deference to the interpretation of statutes by administrative agencies charged with their enforcement, this deference is not given when "the agency's interpretation directly contravenes the words of the statute." Lisney v. Labor & Industry Review Commission, 171 Wis. 2d 499, 505-506, 493 N.W.2d 14, 16 (1992); see also Gorzalski v. Frankenmuth Mut. Ins. Co., 145 Wis. 2d 794, 801, 429 N.W.2d 537, 539-540 (Ct. App. 1988).3
Section 102.555(8), Stats., is clear: "An employer is liable for the entire occupational deafness to which his or her employment has contributed." The Commission's interpretation of § 102.555(8) makes the employer liable for all of an employee's deafness — not just "occupational deafness to which his or her employment has contributed." (Emphasis added.) It thus cannot stand.
The contention that the employer should be liable for pre-employment deafness below the compensable threshold focusses on the following language in § 102.555(8), Stats.: "but if previous deafness is established by a hearing test or other competent evidence ... the employer is not liable for previous loss so established." This, the appellants argue, must mean compensable "deafness" or hearing "loss" under WlS. Adm. Code§ Ind. 80.25 because loss under thirty deci*234bels "does not constitute any practical hearing impairment." See Wis. Adm. Code § Ind. 80.25(4). Thus, they assert that a pre-employment hearing loss must exceed the 30-decibel level before the employer may get credit for that loss. The statute, however, is not so limited.
Hearing loss is progressive; a person reaches the compensable threshold of thirty-one decibels only if he or she has already suffered thirty decibels of loss. Under the Commission's interpretation of § 102.555(8), Stats., adopted by the Dissent, if employee A started work with a hearing loss of thirty decibels, and suffered an additional hearing loss of one decibel during his employment, the employer would be liable for the entire thirty-one decibel hearing loss, even though the employment only contributed just over three percent to the employee's total hearing loss. This interpretation disregards the physiological damage evidenced by decibel loss below the compensable threshold of thirty-one decibels. The statute says that an employer is not liable for the hearing loss that antedates the employment. Nevertheless, both the Commission and the Dissent would make the employer liable for this pre-employment loss.4 Section 102.555(8), STATS., however, is to the contrary; we may not rewrite the statute.
Implementation of § 102.555(8), STATS., and WlS. Adm. Code § Ind. 80.25 requires a three-stage analysis. First, does the employee's hearing loss equal or exceed the compensable threshold of thirty-one decibels? If so, the second question is whether the employee has suffered an "occupational deafness," as defined by *235§ 102.555(1), Stats. If so, the third question is whether the employee's "occupational deafness" was caused by the employment at issue. If the answer to each question is "yes," the employer is liable for the "occupational deafness" caused by the employment. The employer, however, is not liable for any pre-employment hearing loss. Rather, the employer is only liable for the percentage of hearing loss caused by the employment. Thus, if employee B started work with a five-decibel hearing loss, and suffered an additional thirty-five decibel "occupational deafness" loss for a total loss of forty decibels, the employer would be liable for 87.5% of the forty-decibel loss (thirty-five divided by forty).5 By the same token, if employee C started work with a thirty-five decibel hearing loss, and suffered an additional thirty-five decibel loss for a total loss of seventy decibels, the employer would be liable for 50% of the seventy-decibel loss. Similarly, in the example involving employee A, the employer would be liable for 3.23% of the thirty-one decibel loss (one divided by thirty-one).6
*236We affirm the trial court's orders. Further proceedings before the Commission are to be in conformity with this decision.
By the Court. — Orders affirmed.
An amicus brief in support of the appellants was submitted by the Wisconsin Academy of Trial Lawyers.
Section 102.555(8), Stats., provides in full:
*232An employer is liable for the entire occupational deafness to which his or her employment has contributed; but if previous deafness is established by a hearing test or other competent evidence, whether or not the employe [sic ] was exposed to noise within the 2 months preceding such test, the employer is not liable for previous loss so established nor is the employer liable for any loss for which compensation has previously been paid or awarded.
Indeed, "[a]n administrative rule, even of long duration, may not stand at variance with an unambiguous statute," Basic Products Corp. v. Department of Taxation, 19 Wis. 2d 183, 186, 120 N.W.2d 161, 162 (1963), because "[n]o agency may promulgate a rule which conflicts with state law," § 227.10(2), STATS.
Thus, the table on page 244 of the Dissent has employer B liable for the entire forty decibel loss, even though that employment only caused twenty decibels of that loss.
These calculations assume that hearing loss is linear; if it is not, the calculations may have to be changed but the analysis remains the same. Under § 102.555(8), Stats., the employer is only liable for the percentage of hearing loss caused by the employment.
In their brief on this appeal, appellants posit the following hypothetical:
Employee Smith begins work as a paper machine operator at a plant in Rhinelander, Wisconsin, and is subjected to noise causing hearing loss. He works at the same plant location, on the same machine, for the same supervisors producing the same product, for thirty years. At the start of his employment, he has "perfect" hearing, zero db results on testing. After ten years, he has 20 db of loss, and the plant is sold from ABC Corporation to DEF Corporation. While the ownership changes, the job remains the same for Smith, working day-in and day-out at his paper machine. After 20 years of *236work, the plant again is sold, this time to XYZ Corporation, and Smith's testing now reflects a 40 db loss. He continues employment for 10 more years, retiring with honor after a total of 30 years of service operating the same paper making machine. He now has a 60 db loss, cannot hear the telephone ring, and turns up the TV volume to such high levels that he irritates his family, and he must finally admit to his impairment and purchase a hearing aid.
Assuming without deciding the validity of the assumption concerning the legal import of the change-of-ownership scenario, under § 102.555(8), STATS., DEF Corporation would be liable for its contribution to Smith's "occupational deafness," that is, fifty percent (twenty divided by forty), and XYZ Corporation would be liable for its contribution to Smith's "occupational deafness," that is, thirty-three and one-third percent (twenty divided by sixty).