OPINION
NELSON, Presiding Judge.This decision presents for review the question of the validity of Rule 13d, Rules of Procedure for Workmen’s Compensation Hearings Before the Industrial Commission of Arizona (November 1, 1973). We hold that Rule 13d, hereinafter quoted, as applied by the hearing officer is in excess of the statutory rule making grant to the Industrial Commission of Arizona. We also hold that the rule itself does not mandate the hearing officer’s legal conclusion and when viewed in the light of this opinion the rule does not fall within constitutional prohibitions. This holding requires that the award in this case be set aside.
The general law regarding the power and authority of an administrative agency to make rules and regulations to carry out its statutory responsibilities is clear. An administrative agency must exercise any rule making authority granted by statute within the framework of that statutory grant. There is no authority or power to create a rule or regulation out of harmony with the statutory grant and any effort to do so will be considered an usurpation of the constitutional powers vested in the legislative body. If there is a legislative grant of authority, however, the agency may make rules and regulations supplementing the legislation for its complete operation and enforcement, so long as such rules and regulations are within the standards set forth in the act of the legislative body. Ruiz v. Morton, 462 F.2d 818 (9th Cir. 1972), affirmed 415 U.S. 199, 94 S.Ct. 1055, 39 L.Ed.2d 270 (1974); Swift & Company v. State Tax Commission, 105 Ariz. 226, 462 P.2d 775 (1969); Haggard v. Industrial Commission, 71 Ariz. 91, 223 P.2d 915 (1950); State Compensation Fund v. De La Fuente, 18 Ariz.App. *291246, 501 P.2d 422 (1972), review denied, 109 Ariz. 439, 511 P.2d 621 (1973).
The general rule making power of the Industrial Commission of Arizona in workmen’s compensation matters is found in A.R.S. § 23-921B. In addition, A.R.S. § 23-1044G authorizes the Commission to adopt “reasonable and proper rules to carry out the provisions of this section”.
Rule 13d, supra, reads thusly:
“If upon discharge from treatment the physician finds that the employee has sustained an impairment of function as the result of the injury, he shall so state in his report. Any ratings of the percentage of functional impairment shall be in accordance with the standards for the evaluation of permanent impairment as published by the American Medical Association in ‘Guides to the Evaluation of Permanent Impairment.’ It shall include a clinical report in sufficient detail to support the percentage rating assigned.”
The foregoing rule admonishes that practitioners of the healings arts (practitioners) who render reports or who testify in workmen’s compensation matters shall give consideration to the AMA guidelines. The rule does not, however, in our view, preclude the practitioners from following other guidelines or their own professional judgment, thus enabling the hearing officers to weigh and evaluate professional evidence which may not be in full accord with the AMA Guides.
The record in the case before us on this matter (see also: Smith v. Industrial Commission of Arizona, 26 Ariz.App. 297, 547 P.2d 1097 (1976); Sanders v. Industrial Commission of Arizona, 27 Ariz. App.-,-P.2d-, Memorandum Decision; Zolman v. Industrial Commission of Arizona, 27 Ariz.App. -, - P.2d -, Memorandum Decision, all filed this date) makes it clear that the exclusive use of the American Medical Association’s “Guides to the Evaluation of Permanent Impairment”, will make it impossible, in a certain number of situations, for the Industrial Commission to make the awards it is required to make pursuant to A.R.S. § 23-1044. While there is some argument made that the rule only governs the calculations and testimony of the physicians and not the determination made by the hearing officer and the Industrial Commission, the decisional law in this jurisdiction prohibiting the substitution of the opinions of either the hearing officers, the Industrial Commission, or the Courts, in matters lying exclusively within the expertise of the medical profession, makes such an argument unsupportable. E. g., State Compensation Fund v. Keefe, 22 Ariz.App. 311, 526 P.2d 1266 (1974); Waller v. The Industrial Commission of Arizona, 99 Ariz. 15, 406 P.2d 197 (1965).
Because of the fact that there can be no serious question that the AMA Guides provide an almost unquestioned accurate measurement of impairment in many cases, and would be evidentiary support even in those cases where its exclusivity is properly objected to, the general maxim that courts should construe language in statutes and rules in a way to avoid an absurd result and to avoid invalidity becomes even more imoprtant here. E. g., State v. AiResearch Mfg. Co., 68 Ariz. 342, 206 P.2d 562 (1949). Technical wording must yield, when the clear statutory intention, such as that in A.R.S. § 23-1044 to fully compensate for the true partial hearing loss of the petitioner here, would be frustrated. E. g., In re Estate of Henry, 6 Ariz.App. 183, 430 P.2d 937 (1967). See also: State Board of Directors for Junior Colleges v. Nelson, 105 Ariz. 119, 460 P.2d 13 (1969). Where, as here, the exclusive application of the AMA Guides would frustate the purpose of the statute, the word “shall” in the rule is interpreted as permissive, rather than mandatory. In addition, because of the general acceptability of the AMA Guides, we have determined that the holding in this case is to be applied prospectively only except as to those cases wherein further review by the Industrial *292Commission of Arizona or this Court is still available. Hollywood, Continental Films v. The Industrial Commission of Arizona, 19 Ariz.App. 234, 506 P.2d 274 (1973). See also: Southern Pacific Company v. Cochise County, 92 Ariz. 395, 377 P.2d 770 (1963); Arizona State Tax Commission v. Ensign, 75 Ariz. 376, 257 P.2d 392 (1953) ; City of Tempe v. Del E. Webb Corporation, 14 Ariz.App. 228, 482 P.2d 477 (1971), Annot., 10 A.L.R.3d 1371 (1966). This decision will not support a petition to reopen, pursuant to A.R.S. § 23-1061H.
In the case at bar, Don C. Adams, the petitioner (Adams), was employed as a machinist with respondent Karlson Machine Works. On September 28, 1973, Adams, while hammering lugs on a large tire rim, hit the rim and there suddenly developed a loud roaring noise in his head. On October 1, 1973, Adams sought the services of Jack Brooks, M.D., a specialist in otorhinolaryn-gology, complaining of a marked loss of hearing in the left ear and ringing or some type of noise present in both ears.
Petitioner filed a claim for workmen’s compensation which was accepted by the carrier. Adams continued under the care of Dr. Brooks until January 28, 1974, when he discharged him from further treatment, rating his permanent impairment as an 11% hearing loss in the left ear. Adams had been fitted with a hearing aid for his left ear and had been released for regular work by Dr. Brooks on December 17, 1973. Employers Mutual Liability Insurance Company of Wisconsin, the respondent carrier (Carrier), issued a notice of claim status awarding Adams compensation for the partial loss of hearing in his left ear, pursuant to A.R.S. § 23-1044B(18) and (21).
Petitioner sought a hearing, claiming he had a greater disability than awarded. At the hearing he sought to show that not only was the percentage of hearing loss in his left ear greater than allowed, but that the accident had also caused a total loss of hearing in his right ear. The hearing officer found that the 11% hearing loss in the left ear was correct and that Adams failed to carry his burden of proof regarding the causal connection between his admitted total loss of hearing in the right ear and the accident in question. After the hearing officer affirmed his decision on review, the matter was brought here for consideration.
We have reviewed the record and find that there is ample support in the record for the hearing officer’s determination that Adams failed to carry his burden of proof regarding the causal connection between his loss of hearing in the right ear and the accident. However, the application of Rule 13d, supra, and through it the exclusive use of the AMA Guides to require a finding of 11% loss of hearing in the left ear, even though the only medical doctor present testified that but for the binding nature of the AMA Guides, Adams actually suffered a greater loss of hearing in the left ear, requires that the award be set aside.
Although Larry J. Lovering, a Ph.D. and an Audiologist who examined Adams at the request of Dr. Brooks for the purposes of measuring his hearing and fitting Adams with a hearing aid testified, Dr. Brooks made the calculations resulting in the determination of an 11% loss of use of hearing in the left ear. Dr. Brooks was the only medical doctor whose records were in evidence and who testified in this case. In order to show how the mandatory use of the AMA Guides prevented Dr. Brooks, and thus the hearing officer and the Commission, from establishing Adams’ actual partial loss of hearing in his left ear, as required by A.R.S. § 23-1044B(21), it is necessary to set forth the record at some length.
After Dr. Brooks had given the 11% rating according to the AMA Guides on direct examination, the following foundational questions and answers were given:
“Q. Doctor, you say in your report there that 11 percent does not truly reflect the loss because of the loss of the higher tones. Could you explain that statement ?
*293“A. Well, the percentage, according to this method of calculation, does not actually reflect the loss in the normal function of conversation.
“Q. Is there another rating scale which would more truly and correctly reflect Mr. Adams’ loss?
“A. The Department of Labor has a relatively new standard which they feel more closely reflects the amount of functional loss.
“Q. Are you familiar with that standard and the formula by which it operates?
“A. Yes, I am.
“Q. Do you have an opinion as to which standard would more correctly reflect his true loss?
“A. I think — I think today it is felt that the Department of Labor’s schedule more closely reflects the actual loss.
“Q. Have you computed the loss of hearing according to that standard?
******
“THE WITNESS: The answer is Yes.”
Following this answer an objection was interposed as to a further reference to the Department of Labor standard, it being urged that the terms of Rule 13d mandate the use of the AMA Guides. The hearing officer’s position is clear:
“THE HEARING OFFICER: Perhaps you’ll be on the committee for changing the rules, Mr. Gibson. The rules presently provide that any permanent impairment must be on the A.M.A.’s guide for permanent impairment.
“MR. GIBSON: Regardless of whether that rule truly reflects what the actual loss is ?
“THE HEARING OFFICER: I’ll let him answer. You’ll have to understand that’s what the rules provide at this time, at least. So, in other words, what I’m saying, I couldn’t consider that.
“Q. BY MR. GIBSON: Well, what loss in the left [ear] did you find, according to that standard, Doctor?
****** “THE WITNESS: I would like to preface my answer by saying I’m not acquainted with what determines compensation or what are the rules.
According to the formula of the U.S. Department of Labor he would have — his loss in the left ear would be calculated at 30 percent loss.”
Thus we have an eminently qualified specialist, a member of the A.M.A. as well as his own specialty group within that organization, testifying unequivocally that at the time of the hearing in this case, the AMA Guides, in this area at least, did not accurately reflect Adams’ true loss of hearing and that the new guides published by the United States Department of Labor did accurately reflect the loss.
The hearing officer did not believe that he had the authority under the rules, supra, to consider the testimony contrary to, or from a source other than the AMA Guides. His analysis of his responsibility under Rule 13d was erroneous as a matter of law and constituted the prejudicial exclusion of competent medical opinion. A rule which would prohibit the consideration of valid evidence would be invalid.
A.R.S. § 23-1044B(21), supra, provides for the payment of compensation for the partial loss of hearing. A formula for computation is set out based on the percentage of loss and the amount of compensation to be paid for total loss of hearing in one ear found in A.R.S. § 23-1044B (18). The statute says nothing about partial loss, as computed by the AMA Guides.
When the evidence clearly shows that in fact the application of the rule makes it impossible to fulfill the dictates of the statute regarding the awarding of benefits for partial loss of hearing, it must be said that the rule, as interpreted by the hearing officer, is not “reasonable and proper rules to carry out the provisions of this section”. A.R.S. § 23-1044G, supra, and cases cited therewith.
*294Nothing in this opinion or the other cases decided this day should be read in a light unfavorable either to the AMA Guides or to the use of them by the Industrial Commission in this difficult area. In many situations these AMA Guides will not only be a sufficient foundation for an award in these types of cases, it may well be the only authoritative source upon which a reasonable award can be based. As can be seen in this case, there are, however, other valid standards and opinions which must be available to the hearing officer and the Commission in making these difficult decisions if they are to fulfill the mandates of the Legislature in making the awards. Rule 13d, supra, as interpreted by the hearing officer, prevents them from fulfilling those statutory mandates, and was given an invalid and too restrictive interpretation.
The award is set aside.
HENRY S. STEVENS, Judge, Retired, concurs.NOTE: The Honorable HENRY S. STEVENS, Judge, retired, was called to participate in the disposition of this matter.