Citation Nr: 21070059 Decision Date: 11/22/21 Archive Date: 11/22/21 DOCKET NO. 12-23 607 DATE: November 22, 2021 ORDER Entitlement to service connection, to include on a secondary basis, for bilateral hearing loss is denied. FINDING OF FACT The Veteran's bilateral hearing loss did not originate in service, within a year of service, and is not otherwise etiologically related to his active service. CONCLUSION OF LAW The criteria for service connection for bilateral hearing loss have not been met. 38 U.S.C. §§ 1110, 5103, 5103A, 5107; 38 C.F.R. §§ 3.102, 3.159, 3.303, 3.307, 3.309. REASONS AND BASES FOR FINDING AND CONCLUSION The Veteran served on active duty from October 1966 to October 1970. This matter is before the Board of Veterans' Appeals (Board) on appeal from a June 2010 rating decision by a Department of Veterans Affairs Regional Office (RO). In July 2014, the Veteran testified at a Board videoconference hearing before the undersigned. A transcript of that hearing is associated with the claims file. By way of history, in a February 2020 decision, the Board denied the service connection claim on appeal. The Veteran appealed the Board's decision to the U.S. Court of Appeals for Veterans Claims (Court). In a December 2020 Order, the Court vacated the Board's decision and remanded for readjudication in compliance with the Joint Motion for Remand (JMR). In pertinent part, the JMR found that Board erred by relying on an inadequate April 2019 VA examination with respect to whether the bilateral hearing loss was aggravated by the service-connected tinnitus. Thereafter, this matter was remanded in May 2021 to obtain a VA examination. The Board notes that the requested VA examination was obtained in July 2021 and has been associated with the claims file. Service Connection Service connection may be granted for a disability resulting from disease or injury incurred in or aggravated during service. 38 U.S.C. § 1110; 38 C.F.R. § 3.303. In order to establish entitlement to service connection, there must be (1) evidence of a current disability; (2) medical, or in certain circumstances, lay evidence of in-service incurrence or aggravation of a disease or injury; and (3) a causal connection between the claimed in-service disease or injury and the current disability. Shedden v. Principi, 381 F.3d 1163 (Fed. Cir. 2004). With respect to hearing loss, VA has specifically defined what is meant by a "disability" for the purposes of service connection: "[I]mpaired hearing will be considered to be a disability when the auditory threshold in any of the frequencies 500, 1000, 2000, 3000, 4000 Hertz (Hz)is 40 decibels or greater; or when the auditory thresholds for at least three of the frequencies 500, 1000, 2000, 3000, or 4000 Hz are 26 decibels or greater; or when speech recognition scores using the Maryland CNC Test are less than 94 percent." 38 C.F.R. § 3.385. The threshold for normal hearing is from 0 to 20 decibels, and higher threshold levels indicate some degree of hearing loss. Hensley v. Brown, 5 Vet. App. 155, 157 (1993). The Veteran seeks entitlement to service connection for bilateral hearing loss. Specifically, he asserts that his bilateral hearing loss is etiologically related to in-service noise exposure due to his military occupational specialty (MOS) as a jet engine mechanic. See December 2006 Letter. Alternatively, he asserts his bilateral hearing loss was caused or aggravated by his service-connected tinnitus. See October 2016 Board Remand. Factual Background The evidence of record includes service treatment records (STRs). The Board notes that the Veteran served between October 1966 and October 1970. In this regard, prior to January 1967, it is assumed that hearing tests were conducted using the ASA standard. For hearing tests conducted after January 1, 1967, and prior to December 31, 1970, unless indicated, it is unclear whether such thresholds were recorded using American Standards Association (ASA) units or International Standards Organization-American National Standards Institute (ISO-ANSI) units. In light of the above, audiometric data originally recorded using ASA standards will be converted to ISO-ANSI standard as noted below. The STRs include an August 1966 enlistment examination showing the Veteran denied any hearing loss. The examination further noted the following audiometric testing results: ASA Standard HERTZ 500 1000 2000 3000 4000 RIGHT 5 -5 -5 5 15 LEFT 0 -5 5 15 65 ISO-ANSI Standard HERTZ 500 1000 2000 3000 4000 RIGHT 20 5 5 15 20 LEFT 15 5 15 25 70 The Veteran underwent another in-service audiological evaluation in April 1967 which noted the following audiometric testing results: ASA Standard HERTZ 500 1000 2000 3000 4000 RIGHT -10 -10 -5 5 15 LEFT -10 -10 -10 20 25 ISO-ANSI Standard HERTZ 500 1000 2000 3000 4000 RIGHT 5 0 5 15 20 LEFT 5 0 0 30 30 A March 1969 audiological evaluation specifically noted that ISO standards were used. The following audiometric testing results were noted: ISO-ANSI Standard HERTZ 500 1000 2000 3000 4000 RIGHT 10 10 20 30 25 LEFT 10 10 20 20 20 The Veteran additionally underwent an audiometric evaluation in June 1970 which noted that ISO standards were used. That evaluation noted the following: ISO-ANSI Standard HERTZ 500 1000 2000 3000 4000 RIGHT 0 5 5 10 10 LEFT 15 5 0 0 5 The August 1970 separation examination shows the Veteran specifically denied any hearing loss or ENT trouble. The examination noted the following audiometric testing results: ASA Standard HERTZ 500 1000 2000 3000 4000 RIGHT 0 5 5 10 10 LEFT 15 5 0 0 5 ISO-ANSI Standard HERTZ 500 1000 2000 3000 4000 RIGHT 15 15 15 20 15 LEFT 30 15 10 10 10 Post-service medical records include audiometric examinations conducted by the Veteran's employer (TVA). See Private Medical Records Received January 2009. Those records include an April 1973 evaluation noting the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT -10 -10 -10 -5 0 LEFT -10 -10 -5 10 20 Over three years later, an October 1976 evaluation noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 0 0 0 5 15 LEFT 0 0 5 15 20 In January 1980, the following audiometric testing results were noted: HERTZ 500 1000 2000 3000 4000 RIGHT 5 0 0 15 25 LEFT 5 5 5 15 30 Approximately four years later, an October 1984 evaluation noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 5 0 0 20 35 LEFT 5 5 40 55 55 Similar audiometric testing results were shown in July 1989. A January 1991 evaluation noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 5 5 5 25 40 LEFT 5 5 50 60 60 September 1993 and 1995 TVA audiological evaluations continued to show thresholds showing bilateral hearing loss for VA purposes with the 1995 evaluation noting thresholds of 45 and 50 dB at 3000 and 4000 Hz respectively. In December 2006, the Veteran submitted a private audiological examination noting the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 5 5 15 60 55 LEFT 5 10 60 70 85 Speech recognition scores were 100 percent for the right ear and 88 percent for the left ear, although the examination report did not indicate whether Maryland CNC word testing was utilized. The audiologist noted the Veteran served 4.5 years in the Air Force as a jet engine mechanic exposing him to extreme noise. The audiologist also noted that he worked 29 years as a crane inspector also exposing him to traumatic noise. The audiologist opined that the "type and degree of hearing loss could certainly have been initiated in military service and tinnitus was very likely caused in military." Additionally, in a December 2006 letter, the Veteran reported working in the engine room and thereafter working on the flight line where he installed and removed aircraft engines. As a result, he reported being exposed to extremely loud engine noise. He did report wearing hearing protection that was provided. The Veteran initially underwent a VA examination in March 2007. The examiner noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 10 5 25 55 60 LEFT 10 10 55 70 85 Speech recognition scores were 96 percent for the right ear and 88 percent for the left ear. The examiner noted the Veteran was exposed to significant amounts of loud noise during service. The examiner further noted that the enlistment and separation examinations were not contained in the claims file. Therefore, a nexus opinion could not be provided without resorting to speculation. In a March 2007 addendum opinion, the examiner noted that a review of the August 1966 enlistment examination showed normal hearing for the right ear with high frequency hearing loss shown for the left ear. The examiner also noted April 1967 and 1969 audiological examinations showing bilateral hearing within normal limits during service and at separation from service. Based on a review of the claims file, the examiner opined that the current hearing loss was "not as least as likely as not related to noise exposure during service." In October 2009, the Veteran submitted private ENT records which noted a history of noise exposure and an opinion stating it was "likely that at least some of his hearing loss is due to his noise exposure in US military service." No rationale was provided. See Private Medical Records Received October 2009. The Veteran underwent another VA examination in March 2010. The examiner noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 5 10 25 60 65 LEFT 5 10 60 70 85 Speech recognition scores were 96 percent for the right ear and 84 percent for the left ear. The examiner noted the Veteran was already service connected for tinnitus. The examiner additionally noted an August 1966 enlistment examination indicating normal hearing for the right ear and moderate to moderately severe high frequency hearing loss for the left ear. In addition, the examiner noted that additional in-service audiometric testing as well as the August 1970 separation examination showed normal bilateral hearing. Following service, the examiner noted a 1973 occupational hearing evaluation showing normal bilateral hearing for VA purposes with mild hearing loss at 6000 Hz for the left ear. Thereafter, later occupational hearing evaluations evidence bilateral high frequency hearing loss. The Veteran reported occupational noise exposure prior to service while working at a rubber plant for one year without the use of hearing protection. Post-service occupational noise exposure included 29 years of working for the TVA during which he reported use of hearing protection. He denied any recreational noise exposure. The examiner opined that it was "less likely as not" that the current bilateral hearing loss was caused by or the result of noise exposure during service. The examiner based this opinion on an Institute of Medicine Report conclusion that hearing loss occurred immediately, and that there was no scientific support for delayed onset hearing loss. Based on that finding, the examiner noted that the Veteran's hearing was normal at the time he separated from service and that he was exposed to significant noise exposure during his 29 year post-service career. The Veteran submitted a letter from his private audiologist in March 2011. The audiologist opined that it was "more likely than not that his hearing loss and his constant ringing tinnitus were initiated in military service." The audiologist based this opinion on the enlistment examination showing significant hearing loss in the left ear with future hearing tests showing normal hearing in both ears. Accordingly, the audiologist called into question the hearing examinations conducted during service. See Private Medical Records Received March 2011. In his March 2011 notice of disagreement (NOD), the Veteran asserted that his separation audiological evaluation was done without an actual hearing test. The Veteran also submitted medical studies with regard to hearing loss among people who worked on flight crews noting harmful effects from jet engine noise. At a July 2014 Board hearing, the Veteran testified that while he was provided with hearing protection during service, that such protection was insufficient to protect against hearing loss. In March 2015, he submitted a January 2015 letter from a private audiologist who stated the Veteran had not worked prior to service. Accordingly, it was noted that his first extreme noise exposure was associated with active duty service due to jet engine noise. In addition, the audiologist noted that his first job after service showed high frequency hearing loss and, therefore, it could only be concluded that hearing loss occurred during service. In a February 2015 Revised Report of Audiological Evaluation, the Veteran reported experiencing increased difficulty hearing and understanding conversational speech over the past ten years. He also reported that his hearing loss began during active duty service due to in-service noise exposure to jet engines with use of hearing protection. Following service, he reported employment with TVA and stated that hearing protection was also used during that time. Recreational noise exposure from gunfire with hearing protection was also reported. An audiological evaluation revealed the following results: HERTZ 500 1000 2000 3000 4000 RIGHT 20 15 50 65 65 LEFT 25 25 70 90 95 The audiologist noted that the only history of exposure to excessive noise reported by the Veteran occurred during service with no other factors reported that would have predisposed him to hearing loss other that in-service noise exposure. Accordingly, the audiologist opined that the Veteran's hearing loss was "more likely than not" caused by, resulted from or was worsened by active duty service. At an April 2015 VA examination, the examiner noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 10 10 45 60 65 LEFT 15 10 65 90 85 Speech recognition scores were 96 percent for the right ear and 72 percent for the left ear. With regard to the right ear, the examiner opined that it was not "at least as likely as not (50% probability or greater)" that hearing loss was etiologically related to service. In support of this opinion, the examiner noted normal hearing evaluations during service, including at separation from service. The examiner further noted that even when converting in-service audiological evaluations from ASA to ISO, such results still evidenced normal hearing for the right ear during service. Accordingly, the examiner noted no evidence showing a significant threshold shift for the right ear throughout service. The examiner also noted a 2006 Institute of Medicine finding of an insufficient scientific basis for concluding that permanent hearing loss could develop from noise exposure long after such exposure. The examiner also found the March 2011 private nexus opinion speculative since STRs were not reviewed by the audiologist and that the opinion was instead based on lay statements. In this regard, the examiner noted that a 1973 hearing evaluation found normal hearing in the right ear, that the Veteran was exposed to significant traumatic noise during his 29 year career at TVA, and that his employment hearing tests documented right ear hearing loss beginning in 1984. Accordingly, the examiner found it not likely that the current right ear hearing loss was caused by noise exposure during service. Further, based on the above, the examiner found it not likely that noise exposure during service caused or aggravated any right ear hearing loss. With regard to the left ear, the examiner also opined that it was not "at least as likely as not (50% probability or greater)" that hearing loss was etiologically related to service. In support of this opinion, the examiner noted that the August 1966 enlistment hearing evaluation was done utilizing a Bekesy audiogram which was a patient driven test often completed in a non-sound-proof room and, therefore, subject to error. In addition, the examiner noted that all proceeding hearing evaluations evidenced normal hearing for the left ear even when converting from ASA to ISO. The remainder of the rationale relied on the same conclusions noted for the right ear, including reliance on the 2006 Institute of Medicine findings. In a December 2016 VA addendum examination report, the examiner noted a review of the claims file as well as the cited medical articles. The examiner opined that it was "less likely as not" that the bilateral hearing loss was related to in-service noise exposure. With regard to the right ear, the examiner noted normal hearing documented throughout service, including at entrance and separation with no significant threshold shift evidenced. With regard to the left ear, the examiner noted that moderate high frequency hearing loss was evident at enlistment indicative of left ear hearing loss prior to service. The examiner further noted normal left ear hearing documented on all following in-service hearing tests with no significant change in thresholds evidenced. It was further noted that a 1973 post-service employment hearing test documented high frequency hearing loss with no significant threshold shift found when compared to the enlistment examination. Therefore, if hearing loss existed prior to service, the examiner concluded that there was not a significant change in the condition as a result of military noise exposure, and the evidence showed changes in thresholds due to post-service occupational noise exposure. The examiner further noted that there was a question as to the validity of the enlistment examination results, and therefore, if the enlistment examination was not valid then the remainder of the STRs evidenced normal hearing. With regard to the private audiologist opinions, the examiner found such opinions speculative as they only considered in-service noise exposure and did not address the significant post-service noise exposure. The examiner further noted that the Veteran's in-service testing was not reviewed. With regard to the medical articles submitted by the Veteran, the examiner noted that one study indicated permanent damage following "temporary" thresholds shifts, a finding not evidenced by the Veteran's STRs. Additionally, with regard to both studies, the examiner found the 2006 Institute of Medicine Report conclusion that most pronounced effects occurred immediately following traumatic noise exposure more probative as it was a valid study. A February 2017 VA medical record shows the Veteran underwent a brain MRI study related to his bilateral hearing loss. The MRI study noted no acute intracranial abnormality, and no etiology was identified to explain his asymmetric hearing loss. See VA Medical Records Received February 2018. In an April 2017 VA Form 21-4138, Statement in Support of Claim, the Veteran asserted that during a December 2016 VA audiological evaluation, he was referred for an MRI at a VA ENT clinic. The MRI study did not show any tumors. In addition, he asserted that the VA physician told him his hearing loss was due to in-service noise exposure and he needed to be seen yearly for follow-up audiological evaluations. In another VA Form 21-4138, his spouse stated she had been married to the Veteran for the past 47.5 years, and that they were married shortly after he separated from service. In addition, the spouse asserted he had difficulty with hearing loss and tinnitus while he was in the Air Force. March 2017 and March 2018 VA otolaryngology consultation records show reports of slowly progressive hearing loss since discharge from service with significant in-service noise exposure from guns and jet aircraft. The audiologist stated that the bilateral hearing loss was most likely related to a significant noise exposure history. See VA Medical Records Received February 2018 and April 2019. Another VA addendum examination report was obtained in April 2019. The examiner found it "less likely as not that hearing loss is caused by the Veteran's service-connected disability." In this regard, the examiner found that tinnitus and hearing loss could occur individually and without the presence of the other. The Veteran's hearing sensitivity was noted as normal during service with no significant threshold shifts found. Accordingly, although tinnitus was found service-related, hearing loss had not been found to have occurred during active duty service and the evidence showed hearing loss occurred after separation from service. In addition, the examiner noted that tinnitus was a phantom auditory sensation which did not cause or contribute to impaired hearing. Accordingly, the examiner opined that it was "less likely as not that hearing loss has been permanently worsened beyond normal progression by the Veteran's service-connected tinnitus. In an August 2020 letter, the Veteran denied that he reported working for a rubber factory prior to service, and further stated that he was not employed prior to service. He last underwent a VA examination in July 2021. The examiner noted the following audiometric testing results: HERTZ 500 1000 2000 3000 4000 RIGHT 10 10 50 65 65 LEFT 15 15 65 90 90 Speech discrimination scores were 86 percent for the right ear and 70 percent for the left ear. The examiner opined that it was not "at least as likely as not (50% probability or greater)" that the bilateral hearing loss was etiologically related to service. While conceding that the Veteran's MOS likely exposed him to noise levels that could have produced permanent hearing damage, the examiner found that exposure to noise in isolation of any objective audiometric evidence of any noise related injury was insufficient to establish a nexus associated with in-service noise exposure. In this regard, the examiner noted that the STRs were reviewed, but when comparing the enlistment and separation examinations, no evidence of any significant change in hearing thresholds was found (i.e., 15 dB or greater at any frequency, or a shift of 10 dB or greater in the average across 2000 to 4000 in either ear). In addition, with regard to the left ear, the examiner noted that although the enlistment examination indicated hearing loss at 4000 Hz, that all subsequent in-service audiometric testing showed normal hearing at that range. Additionally, with regard to any left ear hearing loss that existed prior to service at 4000 Hz, the examiner opined that the condition was not aggravated beyond normal progression during service. In support of this opinion, the examiner again noted that all in-service audiometric testing following the enlistment examination noted normal hearing at that range, and, therefore, there was no evidence of any positive change or worsening in left ear hearing thresholds during service. Instead, the examiner noted that the in-service audiometric data for the left ear evidenced improvement during service. With regard to secondary service connection, the examiner opined that it was "less likely as not (50 percent or greater probability), that the bilateral hearing loss was proximately due to or the result of the bilateral tinnitus. The examiner further opined that the bilateral hearing loss was "less likely as not aggravated beyond its natural progression by the service-connected bilateral tinnitus." In support of both opinions, the examiner noted that tinnitus was defined as the auditory perception of sound in the absence of an external sound source, and that the condition was a symptom or side effect of some other underlying health condition including, but not limited to, excessive noise exposure and hearing loss. In addition, the examiner stated that tinnitus did not cause hearing loss, or effect or change a person's hearing sensitivity or hearing thresholds. It was further noted that there was no evidence in scientific literature to support any finding that tinnitus caused or was an agent in causing change or aggravation of hearing loss. Finally, the examiner noted that the STRs did not evidence a positive shift in any degree of hearing thresholds during service. Legal Analysis The medical evidence shows thresholds establishing bilateral sensorineural hearing loss for VA purposes. 38 C.F.R. § 3.385. The evidence further shows the Veteran's MOS during service was jet engine mechanic. Therefore, in-service noise exposure is conceded. Accordingly, the remaining inquiry on appeal is whether the bilateral hearing loss is otherwise related to the Veteran's service. After a review of all the evidence, the Board finds that service connection for bilateral hearing loss is not warranted. Initially, the Board notes that the Veteran was assessed with left hearing loss upon entry to service (40 dB at 4000 Hz) with normal hearing noted for the right ear. In this regard, a veteran is considered to have been in sound condition when examined and accepted for service, except as to defects, infirmities, or disorders noted on his entrance into service, or when clear and unmistakable evidence demonstrates that the disability existed prior to service and was not aggravated by service. See 38 U.S.C. § 1111; 38 C.F.R. § 3.304(b). Evidence of a veteran being asymptomatic upon entry into service, with an exacerbation of symptoms during service, does not constitute evidence of aggravation; instead, the evidence must establish that the preexisting condition worsened. See Green v. Derwinski, 1 Vet. App. 320, 322-23 (1991). A preexisting injury or disease will be considered to have been aggravated by active military, naval, or air service, where there is an increase in disability during such service, unless there is a specific finding that the increase in disability is due to the natural progress of the disease. 38 U.S.C. § 1153; 38 C.F.R. § 3.306. With regard to the initial inquiry on appeal, the Board finds the February 2016 VA addendum opinion the most probative evidence of record. In this regard, the examiner found no significant threshold changes for the left ear during service with a normal left ear evaluation noted on a 1973 employment audiological evaluation. Accordingly, the examiner concluded that military service did not result in any significant change in the condition, if it preexisted service. The VA examiner's opinion is directly supported by the Veteran's STRs which do not evidence that left ear hearing loss worsened as a result of military service. Instead, a review of the STRs shows thresholds at 4000 Hz decreased with, at worst, 10 dB noted at separation from service. Moreover, a review of the separation examination shows he specifically denied any hearing loss or ENT trouble at that time. Instead, evidence of left ear hearing loss for VA purposes was not noted again until an October 1984 audiological evaluation conducted by the Veteran's employer, some 14 years after separation from service. Importantly, with regard to preexisting left ear hearing loss, there is no competent medical evidence to the contrary. The Board further notes that neither the Veteran nor his representative have asserted that his left ear hearing loss was aggravated as a result of military service, only that the condition was caused as a result of service. The Board notes that the medical evidence of record also raises an issue as to whether the enlistment audiological examination was adequate, and therefore, whether the Veteran actually had left ear hearing loss prior to service. See April 2015 VA Examination. As noted above, the Board finds that the Veteran did have pre-existing left ear hearing loss as such was noted upon entrance to service. However, even if the Veteran did not have hearing loss in his left ear at entrance to service, the Board further finds that entitlement to service connection is not warranted on the same basis as it finds service connection for right ear hearing loss is not warranted. In this regard, the Board notes that the STRs do not reveal any complaints of, or treatment for, hearing loss. Additionally, hearing loss was not found during in-service audiological testing. Instead, the STRs specifically show the Veteran denied any hearing loss during his separation examination and normal hearing was further noted on his employment audiological evaluation in April 1973, October 1976 and January 1980. Instead, the first competent medical evidence showing audiometric findings meeting threshold requirements of 38 C.F.R. § 3.385 is the October 1984 employment examination showing hearing loss in the left ear, and a January 1991 employment examination showing hearing loss in the right ear; some 14 and 20 years following active duty service respectively. With regard to etiology, the Board finds the cumulative VA examination reports the most probative evidence of record. The probative value of medical opinion evidence is based on the medical expert's personal examination of the patient, the physician's knowledge and skill in analyzing the data, and the medical conclusion the physician reaches. Guerrieri v. Brown, 4 Vet. App. 467, 470-71 (1993). The credibility and weight to be attached to these opinions is within the province of the Board. Id. In this regard, the March 2007, March 2010, April 2015, February 2016 and July 2021 VA examination reports all found it less likely as not that the Veteran's current hearing loss was etiologically related to in-service noise exposure. Specifically, each of the above-mentioned VA examination reports noted that in-service audiological evaluations showed hearing within normal limits, including at separation from service. In this regard, the July 2021 VA examiner noted no significant change in hearing thresholds between the enlistment and separation examination, which he defined as 15 dB or greater at any frequency, or a shift of 10 dB or greater in the average across 2000 to 4000 Hz in either ear. The March 2010 examiner further noted normal hearing was shown on a 1973 occupational hearing evaluation and that the Veteran had a 29 year history of noise exposure working at TVA with use of hearing protection. The VA examination reports additionally relied on an Institute of Medicine Report conclusion that hearing loss occurred immediately, and that there was no scientific support for delayed onset hearing loss. The Board recognizes that the 2005 IOM report (which the March 2010, April 2015, and February 2016 VA examiners relied in part, as a basis for a negative nexus opinion) has qualifying or contradictory statements. McCray v. Wilkie, 31 Vet. App. 243 (2019). However, the Board finds that such does not render these opinions inadequate or diminish their probative value. In this regard, the Board notes that the IOM report acknowledged that there was little evidence to address the question of delayed onset noise-induced hearing loss. However, the IOM report's own finding that, based on the anatomical and physiological data available on the recovery process of noise exposure, it is unlikely that delayed hearing loss effects occur is probative. This statement tends to show that the limitation was considered, but the IOM was confident in the available data (anatomical and physiological) to make a conclusion utilizing a strongly worded term ("unlikely"). Indeed, the committee noted its understanding of the mechanisms and processes involved in the recovery from noise exposure as it suggested "a delay of many years in the onset of noise-induced hearing loss following an earlier noise exposure is extremely unlikely." Conversely, the Board finds the private medical opinions of little probative value. With regard to the December 2006 private audiological examination, the Board finds the opinion offered speculative in nature. In this regard, the audiologist found that the type and degree of the Veteran's hearing loss "could certainly have been initiated in military service." The Board notes that speculative language such as "could certainly have" does not create an adequate nexus for the purposes of establishing service connection, as it does little more than suggest a possibility of a relationship. See Warren v. Brown, 6 Vet. App. 4, 6 (1993); Utendahl v. Derwinski, 1 Vet. App. 530, 531 (1991); Stegman v. Derwinski, 3 Vet. App. 228, 230 (1992); Obert v. Brown, 5 Vet. App. 30, 33 (1993). Similarly, the October 2009 medical opinion is speculative as the private physician failed to provide any rationale for the conclusion that it was "likely that at least some of his hearing loss" was due to in-service noise exposure. The March 2011 letter from the Veteran's private audiologist also failed to provide a rationale. Instead, the audiologist called into question the validity of the in-service audiological evaluations because they showed left hear hearing loss at entrance to service with normal hearing noted thereafter. However, the audiologist did not address the etiological question as to why the current hearing loss is related to service. Therefore, the rationale provided is inadequate. Lastly, the Board finds the January 2015 letter from the Veteran's private audiologist and the February 2015 Revised Report of Audiological Evaluation inadequate as they are based solely on the Veteran's lay statements. In this regard, after a review of the evidence of record, the Board finds the Veteran an inaccurate historian. Therefore, the Board finds that any medical opinion based on those lay statements are equally inadequate in determining the nature and etiology of his hearing loss. With regard to the Veteran's lay statements, the Board notes that during his March 2010 VA examination, he reported having worked at a rubber plant for one year prior to service during which he was exposed to traumatic noise without use of hearing protection. He further denied any recreational noise exposure. However, the January 2015 private audiologist letter shows he stated that he did not work prior to service. Additionally, a review of the February 2015 Revised Report of Audiological Evaluation shows he reported exposure to recreational noise exposure from gunfire, despite having denied any recreational noise exposure previously. Neither of the private medical opinions addressed the conflicting lay statements of record. Moreover, the Board recognizes the Veteran's September 2019 VA Form 21-4138 in which he stated that he was only provided a whispered voice test during his separation examination. However, a review of the August 1970 separation examination clearly shows that an audiological examination was conducted, not a whispered test. Accordingly, as the record shows the Veteran provided conflicting lay statements, including statements as to his past traumatic noise exposure, the Board finds that medical opinions based on such lay statements are of little probative value. The Board recognizes the medical literature submitted by the Veteran. This evidence was addressed by the December 2016 VA examiner who noted that the findings in those studies were inapplicable to the issue on appeal. In this regard, the examiner differentiated the facts between the study noting permanent damage following a temporary threshold shift, and the Veteran's STRs which do not note any temporary threshold shift during service. The examiner further found the 2006 Institute of Medicine Report more probative than the submitted studies as the conclusions contained in that report were considered currently valid. Lastly, with regard to the Veteran's assertion that his bilateral hearing loss was caused or aggravated by his service-connected tinnitus, the Board finds the July 2021 VA examination report the most probative evidence of record. The examiner found it "less likely as not that hearing loss" was proximately due to, the result of, or aggravated by, the bilateral tinnitus. In support of this opinion, the examiner noted that tinnitus was the auditory perception of sound in the absence of an external sound source, and that the condition was a symptom or side effect of some other underlying health condition. With regard to hearing loss, the examiner specifically stated that tinnitus did not cause or affect a change in a person's hearing sensitivity or hearing thresholds. In this regard, the examiner further noted that there was no evidence in scientific literature that supported a finding that tinnitus caused, or was an agent in causing or aggravating, hearing loss. While recognizing that the April 2019 addendum VA examination relied on an incorrect aggravation standard that required a permanent worsening, the Board finds that that addendum further bolsters the July 2021 VA examination report. The April 2019 VA examiner found it "less likely as not that hearing loss" was etiologically related to the service-connected tinnitus. In support of this opinion, the examiner noted that while tinnitus was shown to have had its onset during service, the same was not true for hearing loss. In this regard, the examiner noted that tinnitus and hearing loss could occur individually and without the presence of the other, as evidenced by the onset of symptoms. The examiner further noted that tinnitus was not a condition that caused hearing loss. In this regard, the examiner noted that tinnitus was a "phantom auditory sensation" which did not cause or contribute to impaired hearing. The July 2021 VA examiner came to similar conclusions. Accordingly, the Board finds the July 2021 VA examination report well supported and, therefore, probative as to the question on appeal. Importantly, there is no medical evidence to the contrary. The Board also recognizes the representative's November 2021 brief. Apart from several complaints about VA examiners in general, the representative asserts that the July 2021 VA examiner misrepresented what the Department of Defense (DoD) considered a significant threshold shift. In this regard, the representative asserted that the DoD follows the United Stated Department of Labor OSHA regulations. The Board finds the representative's assertion without merit. First, the VA examiner provided a definition of what he considered a significant threshold shift. However, even if one were to consider OSHA regulations, such do not define "significant threshold shift." Instead, 29 C.F.R. § 1904.10 defines "standard shift" as a change in hearing threshold, relative to the baseline audiogram for that employee, of an average of 10 dB or more between 2000 to 4000 Hz. Apart from regulations concerning how a baseline audiogram has to be established (see 29 C.F.R. § 1910.95(g)(5)), which did not occur in this case, as noted above, the July 2021 VA examiner defined "significant threshold shift" as a change in hearing thresholds of 15 dB or greater at any frequency, or a shift of 10 dB or greater in the average across 2000 to 4000 Hz. Accordingly, contrary to the representative's assertion, the VA examiner definition of "significant threshold shift" does appear to coincide with OSHA's definition of standard shift. The representative further asserted that VA had the burden to show why the Veteran did not deserve the benefit of the doubt from the margin of error or inherent uncertainty in audiograms. In this regard, the representative pointed to another Board Decision's discussion of "normal measurement variability." However, the July 2021 VA examiner did not discuss "normal measurement variability." First, with regard to any "burden" espoused by the representative, no such standard exists. Second, with regard to the cited prior Board decision, such does not provide persuasive support for the appellant's appeal. Pursuant to 38 C.F.R. § 20.1303, decisions of the Board are considered nonprecedential in nature. Each case is decided on the basis of the individual facts in light of the applicable law and regulations. Apart from the lack of precedential value, as different evidence in the case of another veteran may have resulted in the grant of service connection, prior Board decisions do not compel the conclusion that the facts in this case warrant an award of service connection. The Board additionally notes that several of the representative's assertions are centered on a disagreement with how the examiner considered and weighed the evidence of record in providing the nexus opinion (see items 2 and 3). Importantly, the representative did not express disagreement with the evidence cited by the examiner, only what evidence the examiner found probative and/or how the examiner interpreted the evidence. In this regard, the examiner has training, knowledge, and expertise on which he relied to form his opinion. Therefore, the Board finds the VA examiner's conclusions more probative than the representative's. Lastly, the representative addressed delayed onset hearing loss, and asserted that VA examiners, in general, err by relying on the IOM report and failing to consider other studies. One cited study, "Delayed Effects of Noise on the Ear" notes only a possibility of delayed onset hearing loss in Wistar rats 12 to 15 months after noise exposure. The cited article titled, "Current Insights in Noise-Induced Hearing Loss: A Literature Review of the Underlying Mechanism, Pathophysiology, Asymmetry, and Management Options," does not discuss delayed onset hearing loss, but does discuss "noise-induced hidden hearing loss," studies showing the prevalence of left ear hearing loss, and preventative measures. Contrary to the representative's assertion, as noted above, the cited article, "Adding Insult to Injury: Cochlear Nerve Degeneration after 'Temporary' Noise-Induced Hearing Loss," was specifically addressed by the December 2016 VA examiner. Finally, with regard to the remainder of the cited medical literature, the examiner does not explain how or why they are relevant to the Veteran's specific case other than to state that the examiner(s) missed them. Without asserting specifically why such studies are relevant to the Veteran's particular case, such as the study on "excitotoxicity," the Board does not find any of the VA examinations inadequate solely on the basis that these articles were not discussed. In consideration of the above, the Board concludes that while the evidence establishes a current disability, the most probative evidence of record does not establish a causal connection between the current disability and service, or between the current disability and the service-connected tinnitus. Accordingly, the Board finds that the third Shedden requirement has not been met and the preponderance of the evidence is against the claim for service connection for bilateral hearing loss. The claim is denied. See 38 U.S.C. § 5107(b); 38 C.F.R. § 3.102; Gilbert v. Derwinski, 1 Vet. App. 49, 58 (1990). S. HENEKS Veterans Law Judge Board of Veterans' Appeals Attorney for the Board C. Lamb, Counsel The Board's decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.