Fort Carson: an army hearing program success story.
The Army Hearing Program (AHP) is evolving from its predecessor, the Army Hearing Conservation Program (AHCP). The AHP strives to prevent noise--induced hearing loss during training and deployment operations without compromising combat effectiveness.
In contrast, the older AHCP is a garrison-based model which worked well in peacetime, but fell short of the mark with the onset of Operations Enduring Freedom and Iraqi Freedom. (1) The failures of the garrison-based AHCP were well-documented by Helfer et al (2) who investigated the rates of noise-induced hearing loss among several audiology clinics in military treatment facilities across the Army. They found that Soldiers who had deployed to a combat zone showed exponentially higher rates of noise-induced hearing loss, acoustic trauma, permanent threshold shift, tinnitus, eardrum perforation, and H3 or H4 profile (defined in Table 1) compared to those who had not deployed. In accordance with Army Regulation 600-60, (3) Soldiers with H3 and H4 hearing profiles are nondeployable pending adjudication by a retention board. (3(p8)) Often, it is senior noncommissioned officers with prior combat experience who are reassigned to a non-noise-hazardous military occupational specialty (MOS) or separated from the Army because of their H3 or H4 profile. Thus, a largely preventable, noise-induced hearing loss deprives the Army of invaluable leadership for junior Soldiers with less (or no) combat experience. Our national security depends on having well-trained Soldiers on the battlefield, and that is why the Army Hearing Program's growth, and growing pains, have involved much more than a name change.
The US Army Medical Command (MEDCOM) Automated Staffing Assessment Model for Preventive Medicine (ASAM PM) currently recommends one Army audiologist and 2.5 audiology technicians for every 18,000 Soldiers as a minimum staffing model. (5) The ASAM PM model reflects the garrison-based AHCP, and is not compatible with the operational hearing services requirements of the new Army Hearing Program. In January 2008, Fort Carson received authorization for a second Army audiologist in preventive medicine as part of the AHP pilot study authorized by the MEDCOM Chief of Staff. This gave us a ratio of 2 Army audiologists and 5 audiometric/ hearing health technicians for our approximately 18,500 Soldiers organic to Fort Carson (double what the current ASAM PM model recommends). The metrics presented in the following sections show that the latter ratio resulted in a higher number of Soldiers fit for deployment and a decrease in the amount of hearing loss at Fort Carson within units engaged in combat operations over the last calendar year. The data demonstrates how the ASAM PM model must evolve along with the new Army Hearing Program.
THE ARMY HEARING PROGRAM AT FORT CARSON
Fort Carson, located in Colorado Springs, Colorado, is quickly growing into one of the Army's largest Army Forces Command bases. Fort Carson currently has a population of approximately 18,500 Soldiers in garrison. Fort Carson's Soldier population is expected to grow to 29,000 by the year 2011 with the addition of 2 more brigade-sized elements. Fort Carson is also a primary projection platform: in addition to our own organic units, hundreds more Soldiers from the Army National Guard and from the Army Reserves are activated and demobilized from their deployments throughout the United States, Europe, and the middle east every year at the Fort Carson Soldier Readiness Processing Center.
As part of the drastic Army-wide military to civilian conversion of audiologist authorizations in the late 1990s and early 2000s, the Army audiologist authorization at Fort Carson disappeared in 2002, concurrent with the onset of Operations Enduring Freedom (October 2001) and Iraqi Freedom (March 2003).
Figure 1 shows that in 2003, the Fort Carson annual (permanent) significant threshold shift [a metric detailed on page 70] rate jumped from 12% to 16%. This reflects the large number of Soldiers who redeployed to Fort Carson from combat theaters with hearing loss. In June 2006, the authorization for an Army audiologist was reinstated under the Department of Preventive Medicine, and the Army Hearing Program was implemented.
Consider for a moment why the current ASAM PM staffing model is impractical. The high number of Soldiers requiring clinical hearing services (diagnostic audiological evaluations) would prevent a sole audiologist from ever leaving the clinic. This means that there is no time available for the single audiologist to train medics and other noise-exposed military personnel on earplug fittings, no time to conduct annual hearing health briefings, and no time for inspections of noise hazardous areas. When preventive efforts are incomplete or nonexistent, the rates of hearing loss will perpetuate, which will further prevent the audiologist from working outside of the clinical demands.
Four elements comprise the Army Hearing Program:
* Hearing readiness
* Clinical hearing services
* Operational hearing services
* Hearing conservation
Although each element is distinct, the failure of one area will have a direct influence on the other three. A detailed explanation of the Army Hearing Program can be found in Special Text 4-02.501: Army Hearing Program. (6)
Hearing readiness implies that Soldiers have the required hearing capabilities, personal protective equipment, and medical equipment for deployment to a combat zone. Required hearing capabilities are set by Army Regulation 40-501. (4) Soldiers with H1 or H2 hearing profile (defined in Table 1) are deployable, provided there is no significant, underlying pathology of the outer, middle, or inner ear.
Every Soldier on Fort Carson is required to take an annual hearing test, a predeployment hearing test, and a postdeployment hearing test using the Defense Occupational and Environmental Health Readiness System-Hear ing Conservation (DOEHRS-HC) audiometers. The DOEHRS-HC hearing profile data feeds into the Army Medical Department Medical Protection System (MEDPROS) medical readiness database, which assigns a hearing readiness (HR) category (defined in Table 1) to each Soldier ranging from Class I to Class IV as shown in Table 2.
The Fort Carson Hearing Program (FCHP) tracks the HR status for all Soldiers on a monthly basis. Figure 2 illustrates 3 important facts:
* The hearing readiness "GO" rate has increased steadily since the addition of a second Army audiologist in January 2008.
* The number of Soldiers who are nondeployable ("NO-GO") due to hearing loss has steadily decreased.
* The population of Fort Carson has increased by almost 3000 Soldiers from June 2007 (16,722) to December 2008 (19,140).
Compare this to Figure 1. In 2000, only 5,075 of Fort Carson's Soldiers received a DOEHRS-HC hearing test and earplug fitting. That number has nearly quadrupled in 8 years as a result of the HR category on MEDPROS.
Our goal is to continue to maintain a minimum of 80% of Fort Carson Soldiers at HR Class I or II. Looking at Figure 2, note how it appears we fell short of our goal of an 80% GO rate from August to November 2007.
These numbers represent the Soldiers from the 2nd Infantry Division who were deployed in support of Operation Iraqi Freedom for 15 months. MEDPROS automatically identified many of those Soldiers as Hearing Readiness Class IV because they were overdue for their annual (12-month) hearing test. The next version of DOEHRS-HC will include an algorithm that takes into consideration the 15-month deployment cycle.
The FCHP emphasizes the importance of appropriate earplug fitting by qualified medical personnel at the Hearing Readiness Section, located at the Soldier Readiness Processing Center. Every Soldier seen for a hearing test is required to show their earplugs and demonstrate knowledge on how to properly insert them. If the Soldier does not bring earplugs with them on the day of testing, they are refitted by the hearing readiness audiology technicians at that time. The flowchart in Figure 3 illustrates the main processes followed by the hearing readiness staff at Fort Carson.
CLINICAL HEARING SERVICES
Clinical hearing services are required in both garrison and deployed settings. Although there is some overlap, the variance in services delivered between these 2 environments is operationally driven: In garrison, comprehensive diagnostic audiological services are provided to Soldiers in HR Class III and IV status. Diagnostic audiology services include fitness for duty evaluations, hearing profiles for readiness, speech recognition in noise tests for Soldiers with H3 hearing profile, significant threshold shift follow-up, acoustic trauma injuries, and difficult to test patients (including Soldiers who attempt to feign or exaggerate hearing loss).
[FIGURE 3 OMITTED]
In deployed settings, hearing injury treatment services may be provided within the confines of the combat support hospital. The primary purpose of diagnostic hearing care in theater is to determine a Soldier's fitness for duty status and to ensure that only Soldiers in need of advanced audiological care are evacuated out of theater.
The significant threshold shift (STS) criteria is a familiar metric used to document trends over time, and we believed it to be the most appropriate tool to evaluate hearing loss trends and our clinical hearing services at Fort Carson. STS is calculated by averaging the patient's hearing thresholds at 2000 Hz, 3000 Hz and 4000 Hz. If the change from the reference (baseline) audiogram is greater than or equal to +10 dB, a positive STS is recorded.
Referring to Figure 1, note that the Fort Carson STS rate in 2002 was equivalent to the Army average STS rate of 12%. In 2003, the STS rate increased to 16%. We believe the increase is the result of 2 factors:
* The initial group of Soldiers who were deployed to the first cycle of Operation Iraqi Freedom did so without the combat arms earplugs which are currently a rapid field initiative issue to all deploying Soldiers. The combat arms earplugs (CAE) allow low level sounds such as speech to pass through unimpeded. The nonlinear filter in the CAE dampens high level impulse noise such as weapons fire. As with all earplugs, proper size and fit are crucial. During the initial deployments for the global war on terror, the CAE and conventional earplugs for Soldiers were often not available, not wanted, or not fitted properly, which resulted in the dramatic STS increase in 2003.
* The elimination of the Army audiologist's authorization from Fort Carson in 2002 resulted in the abandonment of key concepts, such as hearing loss prevention education and the emphasis on hearing protection devices and their proper use.
Generation of relative value units (RVUs) in a clinical audiology setting was the only outcome measure used by the command at that time.
Figure 1 also shows how the Fort Carson Soldier STS rate decreased to 10% (on average) during calendar year 2007. Figure 4 shows a breakdown of calendar year 2008 and a current average STS rate of less than 11%. This represents the lowest rate of STS on Fort Carson since the year 2000 when we were a peacetime Army. The high STS rates in August 2008 (14%) and in December 2008 (15%) are outliers, and reflect a lack of compliance with the hearing program for 2 units undergoing predeployment hearing readiness evaluations compared to similar units at Fort Carson. Even with the outliers, however, the data in Figure 4 demonstrates that the implementation of the Army Hearing Program at Fort Carson has reduced the Soldiers' overall STS rate to less than 11% during a period of continuous active combat deployments. Eliminating the 2 outliers from the post average puts the rest of Fort Carson's STS rate at less than 10%.
A civilian audiologist works in the Ear, Nose and Throat (ENT) Clinic as part of the Fort Carson Hearing Program. The civilian audiologist's main role is to provide diagnostic audiology services to TRICARE * eligible family members, dependents and retirees. Under the Army Hearing Program at Fort Carson, the civilian audiologist only sees Soldiers who are referred by one of the active duty Army audiologists, or by one of the ENT physicians. The civilian audiologist's responsibilities for Soldier care include clinical rehabilitative services (such as dispensing hearing aids), or advanced clinical testing (including electrophysiological tests and vestibular tests). The civilian audiologist also runs the newborn hearing screening program in the hospital and provides diagnostic and rehabilitative care for TRICARE eligible family members.
It is crucial to distinguish the very different role that the civilian clinical audiologist in the ENT or department of surgery has from the active duty Army audiologist (aligned under the department of preventive medicine). Those audiologists' roles are entirely clinical and rehabilitative in nature, and their patient population consists primarily of civilians. Conversely, the active duty preventive medicine audiologist's role is only 50% clinical in nature. The other 50% of the time is preventive and spent outside of the clinic, involved in education and site inspections. Their primary mission is the prevention of noise-induced hearing loss and the improvement of hearing readiness, in the hope that a hearing aid is not required for as many Soldiers in the future. The preventive medicine audiologist's patient population consists almost entirely of Soldiers. Figure 5 illustrates the different clinical hearing services missions of the preventive medicine (active duty) and the ENT (civilian) diagnostic, clinical, and rehabilitative care.
OPERATIONAL HEARING SERVICES
We believe the reduced STS rate at Fort Carson is a direct result of our focus on operational hearing services in the Fort Carson Hearing Program. The primary objective of operational hearing services is the enhancement of Soldier survivability. Hearing is a critical sense that directly affects mission success. The ability to hear in a combat environment is critical because normal hearing allows a Soldier to detect the enemy and maintain effective communication ability and situational awareness in noise. Operational hearing services include education and instruction in tactical communication and protection systems (TCAPS), noise surveillance of hazardous and nuisance noise environments, guidance on noise abatement and control, and emphasis on prevention of hearing injuries through education and readiness to maximize the warfighter lethality and survivability on the battlefield, without compromising communication and situational awareness. Commanders enhance their units' effectiveness by ensuring troops are equipped with proper hearing protection and/or TCAPS.
[FIGURE 5 OMITTED]
Commanders must ensure their units are provided the opportunity to train with these devices and understand their use and importance in maintaining effective communication and situational awareness.
The metrics we developed monitor operational hearing services in garrison, with the intent that Soldiers will "fight as they train," and transfer the training and skills they learned in garrison onto the battlefield. We followed guidance from the Department of the Army Pamphlet 40-501, which states that commanders of noise-exposed personnel must appoint a unit hearing conservation officer. (7) We incorporated this requirement into a post-wide standing operating procedure (SOP), which was endorsed by the Fort Carson installation commander. The SOP states that each unit on Fort Carson is required to formally appoint a company level hearing program officer (HPO). Each HPO must complete a half day of training under the supervision of at least one of the FCHP Army audiologists. The first portion of the class explains the 4 elements of the hearing program, and the HPO's role as extensions of the FCHP core staff. The second portion of the class involves several practical exercises including: examination of the outer ear canal with an otoscope; determination of the proper size earplug for both themselves and their fellow Soldiers; understanding noise reduction ratios; and understanding that not all earplugs are equally protective--some may in fact "over-protect." Attenuation of too much ambient noise could cause a Soldier to reject all hearing protection based on a negative experience with one type.
Each HPO must pass a written and a practical examination. Graduates are issued a certificate of completion and a pocket otoscope, which becomes property of their company when the Soldier leaves the unit. HPOs are expected to arrange for their unit to participate in an annual hearing health briefing from one of the FCHP preventive medicine audiologists. HPOs are also expected to be ready for a site visit to their area from the FCHP staff to ensure their compliance with the hearing program. The flowchart in Figure 6 illustrates the 3 branches of the operational hearing services mission in garrison at Fort Carson.
[FIGURE 6 OMITTED]
Figure 7 shows that the FCHP has trained 321 company level hearing program officers in the last 2 calendar years. In so doing, we exceeded our goal of training an HPO for 222 (80%) of the companies on Fort Carson. Unfortunately we have fallen short of our other goals for operational hearing services in the areas of education and inspections. We had hoped to present an annual hearing safety briefing to the same 222 companies, but only managed to provide 15 company level hearing health briefings. We also failed in our goal to inspect noise hazardous areas for the same 222 companies, only 14 noise hazardous areas were inspected over the last 2 years. We believe this shortfall was due to the deployment of one of our active duty audiologists to Iraq for 120 days, and her residency training at the Captain's Career Course for another 9 weeks in 2008. During her absence, the table of distribution and allowances* showed that Fort Carson had 2 uniformed audiologists on post running the hearing program, while in reality; only one person was available for more than half of the 2008 calendar year. These numbers further support our belief that the preventive medicine staffing model is inaccurate in its estimation that one military audiologist and 2.5 audiology technicians are capable of providing adequate preventive measures for every 18,000 Soldiers under the Army Hearing Program. Using the old staffing model with the new AHP sets Army audiologists up for failure.
The fourth element of the FCHP is hearing conservation. The hearing conservation element is designed to protect noise-exposed government civilian personnel employed at Fort Carson from hearing loss due to occupational noise exposure. This element follows the garrison-based Army Hear ing Conservat ion Program, but applies to noise exposed civilians only, and does not include our Soldier population. There are 7 essential elements included in the hearing conservation component of the FCHP:
* Noise hazard identification
* Engineering controls
* Hearing protectors
* Monitoring audiometry
* Health education
* Program evaluation
Figure 8 shows the annual STS rate for our noise-exposed civilian employees who are enrolled in the Hearing Conservation Section of the Occupational Health Clinic under the FCHP and the Department of Preventive Medicine. Although we track the overall STS rate monthly, we only graph the yearly percentage of STS due to the significantly lower number of civilians enrolled (411 total in 2008). In 2000, 30% of the 128 noise-exposed civilians on Fort Carson showed an annual significant threshold shift. The STS rate for our civilian workforce in 2008 has dropped to 6%, the lowest it has been in more than 8 years, even though the number of civilians tested has more than tripled during the same time period. We contribute our successes to increased interaction with the range control office on Fort Carson. The FCHP is involved in range control's training classes for range safety officers. We do not require the civilian population to participate in the Hearing Program Officer Course, but interestingly, several noise-exposed civilians have learned of our class and asked to participate so that they could assume the responsibility as the hearing program officers for their work areas. Of course we have been happy to oblige and accommodate them in our classes.
The Fort Carson Hearing Program has documented metrics which show the new Army Hearing Program doctrine successfully decreased this post's Soldier and civilian STS hearing loss rate to levels predating the Global War on Terror, while we have been an Army at war. Additionally, the data shows that the addition of a second Army audiologist in calendar year 2008 resulted in an increase of more than 3,000 Soldiers who were fully ready to deploy, compared to calendar year 2007. Our success is attributed to an increased emphasis in operational hearing services, even though we fell short of our goal of providing a full spectrum and triad of operational hearing services to 80% of Fort Carson's companies in garrison. The FCHP metrics show positive trends in all 4 elements: hearing readiness, clinical hearing services, operational hearing services, and hearing conservation. The metrics also suggest that the Army Medical Command's preventive medicine staffing model's current recommendation of one audiologist and 2.5 technicians for every 18,000 Soldiers is insufficient and predestines hearing loss prevention efforts for failure. Finally, the FCHP shows that command emphasis is crucial for a successful hearing program. COL Kathy Gates, Audiology Consultant to The Surgeon General, succinctly states the current reality:
The Army no longer needs to accept hearing loss as an inevitable byproduct of military service.
I thank the following people for their assistance in preparation and review of this paper: COL Kathy Gates, Audiology Consultant to The Surgeon General and Director of the Army Audiology and Speech Center at Walter Reed Army Medical Center.
COL James Terrio, Chief of Preventive Medicine at Evans Army Community Hospital, Fort Carson.
LTC Vicki Tuten, Audiology Staff Officer, Proponency for Office of Preventive Medicine, Office of The Surgeon General.
LTC Nicholas Piantanida, Deputy Commander for Clinical Services, Evans Army Community Hospital, Fort Carson.
Dr Kenneth Stone, MD, Chief of the Occupational Health Clinic, Department of Preventive Medicine, Evans Army Community Hospital, Fort Carson.
CPT Jenny Davis, Hearing Program Audiologist, Occupational Health Clinic, Department of Preventive Medicine, Evans Army Community Hospital, Fort Carson.
Ms Janet Klieman, Medical Librarian at Evans Army Community Hospital, Fort Carson.
(1.) McIlwain D, Cave K, Gates K, Ciliax D. Evolution of the Army hearing program. Army Med Dept J. April-June 2008:62-66.
(2.) Helfer T, Jordan N, Lee R. Postdeployment hearing loss in US Army Soldiers seen at audiology clinics from April 1, 2003, through March 31, 2004. Am J Audiol. 2005;14(2):161-168.
(3.) Army Regulation 600-60: Physical Performance Evaluation System. Washington, DC: US Dept of the Army; February 28, 2008:8.
(4.) Army Regulation 40-501: Standards of Medical Fitness. Washington, DC: US Dept of the Army; September 10, 2008:80.
(5.) US Army Medical Command Automated Staffing Assessment Model for Preventive Medicine. Available at: https://www.us.army.mil/suite/ page/29142. (restricted access) Accessed December 31, 2008.
(6.) Special Text 4-02.501: Army Hearing Program. Fort Sam Houston, Texas: US Army Medical Department Center & School; February 1, 2008. Available at: http://militaryaudiology.org/site/wp-content/images/ st_4_02_501.pdf. Accessed April 28, 2009.
(7.) Department of the Army Pamphlet 40-501: Hearing Conservation Program. Washington, DC: US Dept of the Army; December 10, 1998:2.
CPT Leanne Cleveland, MS, USA
* TRICARE is the DoD health care program for members of the uniformed services, their families, and their survivors. Information available at http://www.tricare.mil.
* Prescribes the organizational structure, personnel and equipment authorizations, and requirements of a military unit to perform a specific mission for which there is no appropriate table of organization and equipment.
CPT Cleveland, AuD, is Chief of the Fort Carson Hearing Program at the Occupational Health Clinic, Department of Preventive Medicine, Evans Army Community Hospital, Fort Carson, Colorado.
Table 1. Army Hearing Profiles (4(p80)) H1 Audiometer average level for each ear not more than 25 dB at 500, 1000, 2000 Hz with no individual level greater than 30 dB. Not over 45 dB at 4000 Hz. H2 Audiometer average level for each ear at 500, 1000, 2000 Hz, or not more than 30 dB, with no individual level greater than 35 dB at these frequencies, and level not more than 55 dB at 4000 Hz; or audiometer level 30 dB at 500 Hz, 25 dB at 1000 and 2000 Hz, and 35 dB at 4000 Hz in better ear. (Poorer ear may be deaf.) H3 Speech reception threshold in best ear not greater than 30 dB HL, measured with or without hearing aid; or acute or chronic ear disease. H4 Functional level below H3 Table 2. Army Hearing Readiness Categories (4(p114)) CLASS I Soldier's unaided hearing is within H1 standards for both ears. No corrective action is required. CLASS II Soldier's unaided hearing is within H2 or H3 standards. Soldier has a current hearing profile assigned (H2 or H3), and a completed Military Occupational Specialty Medical Retention Board (H3) with no active middle ear disease or medical pathology in the ear. If a Soldier wears hearing aids, he must have hearing aids appropriate for hearing loss and a six month supply of batteries. No corrective action is required. CLASS III Soldier's unaided hearing is within H2 or H3 standards. Soldier has a current hearing profile assigned (H2 or H3), and a completed Military Occupational Specialty Medical Retention Board (H3) with no active middle ear disease or medical pathology in the ear. If a Soldier wears hearing aids, he must have hearing aids appropriate for hearing loss and a 6-month supply of batteries. No corrective action is required. CLASS IV Soldiers who do not have a DOEHRS-HC audiogram in their medical record within one year. Soldier requires a hearing examination. This includes Soldiers without a reference baseline audiogram or whose last periodic audiogram is greater than one-year old. Hearing readiness classification is unknown. Figure 1. Percentage of tested Fort Carson Soldiers with significant threshold shift (STS) for the years 2000 through 2007. 2000(556/5075) 10% 2001(727/5866) 12% 2002(551/4461) 12% 2003(521/3239) 16% 2004(731/6733) 11% 2005(1000/7624) 13% 2006(1706/15529) 11% 2007(1980/20084) 10% Note: Numbers in parentheses--(number demonstrating STS/total number tested) Note: Table made from bar graph. Figure 2. The monthly hearing readiness status of the Soldier population of Fort Carson for 2008. Hearing Readiness Hearing Readiness Class I and II Class III and IV ("GO") ("NO-GO") June 07 (N=16722) 84% 16% July 07 (N=16986) 83% 17% Aug 07 (N=16933) 74% 26% Sept 07 (N=17081) 72% 28% Oct 07 (N=17142) 72% 28% Nov 07 (N=17341) 74% 26% Dec 07 (N=17481) 83% 17% Jan 08 (N=17818) 91% 9% Feb 08 (N=18049) 91% 9% March 08 (N=18427) 91% 9% Apr 08 (N=18428) 94% 6% May 08 (N=18514) 94% 6% June 08 (N=18435) 93% 7% July 08 (N=18523) 92% 8% Aug 08 (N=18502) 89% 11% Sept 08 (N=18527) 96% 4% Oct 08 (N=18749) 96% 4% Nov 08 (N=18985) 96% 4% Dec 08 (N=19140) 95% 5% Note: Number in parentheses is total number of Soldiers on Fort Carson as shown in the MEDPROS database. Note: Table made from bar graph. Figure 4. Percentage of tested Fort Carson Soldiers with significant threshold shift (STS) for each month of 2008. % of Fort Carson Soldiers with Significant Threshold Shift JAN 08 (275/2372) 12% FEB 08 (130/1437) 9% MAR 08 (102/1309) 8% APR 08 (104/1119) 9% MAY 08 (68/654) 10% JUN 08 (95/1008) 9% JUL 08 (124/1254) 9% AUG 08 (156/1124) 14% SEP 08 (83/951) 9% OCT 08 (251/2051) 12% NOV 08 (220/1806) 12% DEC 08 (522/3597 15% Note: Table made from bar graph. Figure 7. The cumulative number of trained, company level hearing program officers in Fort Carson units, the number of hearing health briefings presented, and the number of noise inspections performed shown on a monthly basis for 2007 and 2008. # of Hearing # Surprise Inspections # Annual Hearing Program of Noise Hazardous Health Briefings Officers Areas JAN 07 FEB 07 MAR 07 APR 07 MAY 07 JUN 07 JULY 07 2 AUG 07 11 SEP 07 18 OCT 07 18 NOV 07 46 DEC 07 51 JAN 08 63 FEB 08 65 MAR 08 65 APR 08 85 MAY 08 88 JUN 08 159 JUL 08 208 AUG 08 247 SEP 08 281 OCT 08 311 NOV 08 315 DEC 08 321 Note: Table made from bar graph. Figure 8. Percentage of noise exposed civilian employees who are enrolled in the Hearing Conservation Section of the Occupational Health Clinic with significant threshold shift (STS) for the years 2000 through 2008. % Noise exposed Civilians with STS 2000 (39/128) 30% 2001 (50/210) 24% 2002 (42/178) 24% 2003 (34/236) 15% 2004 (21/161) 13% 2005 (23/183) 13% 2006 (35/221) 16% 2007 (24/148) 9% 2008 (24/411) 5% Note: Numbers in parentheses--(number demonstrating STS/total number tested) Note: Table made from bar graph.