Using Supply and Demand to Identify Shortages in the Hearing Health Care Professional Workforce

Abstract

Importance

Hearing loss is a significant public health issue, affecting 23% of individuals aged 12 years and older in the United States. While hearing loss can be efficaciously treated in many cases, shortages in the supply of hearing health care (HHC) professionals may limit uptake.

Objective

To quantify the U.S. HHC professional workforce from 2012 to 2022 and identify areas experiencing HHC professional shortages in 2019.

Design

For HHC workforce supply, we transformed raw data from the National Plan and Provider Enumeration System (NPPES) to create a state- and county-level database of HHC professionals—including audiologists and hearing instrument specialists—from 2012 to 2022. For HHC workforce demand, we use 2019 state- and county-level hearing loss prevalence data from Sound Check and US Census population data. Shortage areas are determined by comparing these measures of demand and supply in 2019.

Participants

Audiologists and hearing instrument specialists with National Provider Identifiers allowing them to bill public and private insurance in the United States.

Main Outcomes and Measures

We define potential shortage areas using a threshold of one or fewer audiologists per 3,500 individuals with hearing loss, and shortage areas using a threshold of one or fewer HHC professionals per 3,500 individuals with hearing loss.

Results

From 2012 to 2022, the number of HHC professionals in the United States increased from 16,770 to 30,704, or over 83%. By the end of 2022, 72.4% of the HHC workforce were audiologists and 27.6% were hearing instrument specialists. Also, in June 2019, 75.0% of US counties were identified as shortage counties, and these counties were disproportionately rural. Ten states, primarily in the South Census Region, are identified as shortage states.

Conclusions and Relevance

Despite workforce growth, many areas of the U.S. continue to experience shortages of HHC professionals, disproportionately affecting rural populations. Addressing these shortages may improve access to care for individuals with hearing loss.

Introduction

Hearing loss affects 23% of those aged 12 and older in the United States (U.S.) and more than two-thirds of U.S. adults over the age of 70 have significant hearing loss.^1,2 In the U.S., there are many documented barriers to hearing healthcare (HHC) use, including a lack of access to specialists.^3,4 To provide adequate care, reasonable proximity to licensed HHC professionals (i.e., audiologists and hearing instrument specialists) is needed, particularly for the aging population among whom hearing loss prevalence is high.² Audiologists are healthcare professionals with advanced degrees who diagnose and treat a wide range of hearing and balance disorders, while hearing instrument specialists are typically trained in fitting and adjusting hearing aids but do not diagnose or manage medical conditions related to hearing.

It is not well understood how HHC professionals are distributed across the U.S. and whether the number of HHC professionals has been growing at pace with rising demand for hearing services.^5–7 Data sources are often limited by being outdated (e.g., Area Health Resource File [AHRF], which was last updated in 2009),⁸ restricted access (e.g., American Speech-Language-Hearing Association [ASHA] membership information),⁶ being for a single state (e.g., Massachusetts licensure information),⁹ missing sole proprietorships (e.g., Occupational Employment and Wage Statistics [OEWS]),¹⁰ or by not containing the census of all HHC professionals (e.g., all of the above-mentioned data sources except single-state licensure data). Because of the scarcity of longitudinal and comprehensive data on the HHC workforce, we have an incomplete picture of the national workforce of HHC professionals, how it changes over time, and where shortage areas exist. One study using a single year of audiologist membership information found that audiologists tend to locate in metropolitan counties with higher median household incomes, younger populations, and lower proportions of older adults reporting hearing difficulty.⁶

This article describes how publicly available National Plan and Provider Enumeration System (NPPES) data from the Centers for Medicare & Medicaid Services (CMS) can be utilized to estimate HHC professionals across areas and over time. We make this state-level panel data on HHC professionals publicly available and compare it to other data sources. Finally, we use this data to identify HHC professional shortage states and counties in 2019 by comparing the supply of HHC professionals to demand as proxied by the number of people with any hearing loss.

Data and Methods

NPPES

The NPPES, administrative data updated monthly by the CMS, is a publicly available option to form reliable estimates of HHC professionals (i.e., audiologists and hearing instrument specialists), but substantial cleaning is required to quantify the workforce.¹¹ Additionally, the NPPES includes practitioner taxonomy codes that can be used to identify specific types of healthcare providers, and practice location information down to the level of address.

The NPPES contains the near universe of licensed practitioners and other entities that provide billable services, prescriptions, or transmit protected data to engage in other covered transactions. The database contains all National Provider Identifiers (NPIs). An NPI has been required since May 23, 2008 to bill private and public insurance plans and transmit health information protected under the Health Insurance Portability and Accountability Act (HIPAA).¹² Registration has no monetary cost and is obligatory for HIPAA-covered entities, including individuals, organizations, and others that transmit protected health data for the sake of transactions for which the U.S. Department of Health and Human Services has adopted standards. These transactions include the transmission of “healthcare claims, payment and remittance advice, healthcare status, coordination of benefits, enrollment and disenrollment, eligibility checks, healthcare electronic fund transfers, and referral certification and authorization.”¹³ The requirements to have an NPI were further extended to individuals with prescriptive authority in May of 2013.¹⁴ In addition to providers having an incentive to keep records accurate for billing purposes, providers are also required to update their NPI records within 30 days of any change in their licensure or professional status. Taken together, billing requirements and legal obligations help us to observe providers entering and exiting the workforce.

This project leverages January, June, and December disseminations of the NPPES from 2012 through 2022 to construct state-level estimates of audiologists and hearing instrument specialists. Only the most recent versions of these files are publicly available, but our research team routinely archived these disseminations, which we used for this paper. We classify providers into two groups of interest, audiologists and non-audiologist hearing instrument specialists, using taxonomy codes. To assign providers to states and counties, we use the state provided in registrants’ primary practice address and do not rely on primary mailing addresses, which could vary from the practice address for members of a large practice or sole proprietors who may use their home address as their business mailing address. Additionally, NPPES data do not include county of practice but do include zip code; therefore, for practices in ZIP codes that cross county boundaries, we assign the practice to the county with the largest share of the ZIP code’s population (using national population estimates from the U.S. Census Bureau from 2012 to 2022). The online appendix provides further information on this data.

HHC Professional Shortage Areas

Currently, there are three categories of Health Resources and Services Administration (HRSA) designations based on the health discipline that is experiencing a shortage: 1) primary care; 2) dental care; and 3) mental health.¹⁵ For primary care geographic designations, the population to provider ratio must be at least 3,500 to 1 to avoid the shortage designation. For dental, the ratio is 5,000 to 1 and for mental health it is 30,000 to 1. Lower thresholds for population designations or geographical designations in areas with unusually high needs are also possible.

We follow HRSA’s logic in creating our own measure of HHC shortage area by 1) determining the relevant population to provider ratio, and 2) allowing lower thresholds for areas with unusually high need. To determine the relevant population, we start with 3,500 people used for primary care, and make the simplifying assumption that the relevant population are those with hearing loss. According to the National Health and Nutrition Examination Survey (NHANES), 22.7 percent of individuals aged 12+ have hearing loss in at least one ear (i.e., any hearing loss),² which suggests that one HHC professional is needed for every 15,419 people nationally.

To allow lower thresholds for areas with unusually high need, we use recent 2019 state- and county-level hearing loss estimates from Rein et al (2024).¹⁶ This paper finds that 11.6% of people across the United States have hearing loss in both ears. These rates range from a low of 6.3% in the District of Columbia to a high of 18.3% in West Virginia. Unfortunately, Rein et al. (2024) do not provide an estimate of hearing loss in at least one ear. We use the estimate of hearing loss in both ears, assuming that hearing loss in at least one ear is similarly distributed as hearing loss in both ears, to estimate the prevalence of hearing loss similar to national rates displayed by Gorman et al. (2016). We scale each state-specific hearing loss in both ears upwards by a factor 1.96 (= 22.7% / 11.6%) to approximate the 22.7% of people with hearing loss in at least one ear according to NHANES data.² We do the same using the top and bottom of each state-hearing-loss estimate’s 95% confidence interval from Rein et al. (2024) to account for uncertainty in their measures of hearing loss. We then multiply these state-specific, any-hearing-loss estimates by the population in each state to identify the number of people requiring audiology services in that state. Additionally, we repeat the same procedure at the county level using county-level hearing loss prevalence information in Rein et al. (2024).

We use these estimates of the number of people requiring audiology services to create two measures of adequacy in access to different types of HHC professionals. No shortage states and counties are those for which the number of people with any hearing loss is fewer than 3,500 per audiologist. Potential shortage states or counties are those for which the number of people with any hearing loss is more than 3,500 per audiologist but fewer than 3,500 per any HHC professional (i.e., audiologists and hearing instrument specialists combined). Shortage states or counties are those for which the number of people with any hearing loss is greater than 3,500 per HHC professional. Our categorization implicitly recognizes that based on substantially different training, licensing, credentialing, and insurance reimbursement requirements, audiologists have the greatest ability to provide for HHC needs, but hearing instrument specialists can contribute in key ways as well.^17–19 We calculate these shortage classifications for 2019 to match the year for which Rein et al. (2024) provide hearing loss estimates.

Results

The downloadable supplemental material (Online Appendix Tables A2–A4) shows our NPPES estimates of HHC professionals by state and month-year. Figure 1 displays national workforce estimates of HHC professionals over time and shows a steady increase among audiologists from 2012 to 2022 of approximately 8,000 (from 13,852 in 2012 to 22,226 in 2022), or over 60%. The number of observed hearing instrument specialists increased by 190% (from 2,918 in 2012 to 8,478 in 2022), or over 5,500. Audiologists decreased as a share of all HHC professionals from 82.6% at the start of 2012 to 72.4% by the end of 2022. Online Figure A1 shows these trends in HHC professionals adjusted per 100,000 population aged 65 and older, which shows increases of 15.7% and 99.2% from 2012 to 2022 for audiologists and hearing instrument specialists, respectively. Combined, audiologists and hearing instrument specialists increased from just under 40 per 100,000 population aged 65 and older in 2012 to just over 52 per 100,000 in 2022.

Figure 1.

NPPES - National Estimates of HHC Professionals

Notes: This Figure displays the trends in HHC professionals from 2012 to 2022 in January, June, and December of each year from the NPPES data.

Figure 2 shows the geographic distribution of audiologist density per 100,000 state population in 2019, color-coding states by density quartile. States in the top quartile of audiologist density are disproportionately clustered in the Midwest and Northeast. Higher density in the Midwest in particular could be the result of the geographic location of large hearing aid manufacturers in Illinois and Minnesota and the dominant role of Midwestern universities in the education of audiologists.^20,21 Meanwhile, 13 of 17 states in the South are in the bottom two quartiles, with eight in the lowest. Online Figure A2 displays an analogous map of state quartiles of audiologist density for the population aged 65 and older and shows a similar distribution to the map for all individuals.

Figure 2.

NPPES – State Quartile Map of Audiologists per 100,000 Population in 2019

Notes: The map shows for each state the density of audiologists per 100,000 residents.

Figure 3 displays a map with our designation of state shortage areas using NPPES HHC professionals relative to the population with any hearing loss. Ten states, mostly in the West and South regions, are identified as having a definitive shortage. These ten states are Arkansas, Georgia, Hawaii, Kentucky, Maine, Mississippi, Nevada, Oklahoma, South Carolina, and West Virginia. When accounting for uncertainty in Rein et al.’s (2024) hearing loss estimates by using the top and bottom of their 95% confidence intervals, estimates vary from eight to eleven states (subtracting Georgia and Maine if using the bottom of the 95% confidence interval; adding Alabama if using the top of the 95% confidence interval). For example, in 2019, Georgia had 19.1% hearing loss (95% CI: 18.3–19.8%), a population of about 10.6 million, 427 audiologists, and 138 hearing instrument specialists. Georgia is therefore classified as a shortage area when using the mean hearing loss estimate ($\frac{\mathrm{10,628,020}\times 0.1905}{427+138}\approx \mathrm{3,585}>\mathrm{3,500}$) but is not classified as a shortage area using the bottom of the 95% CI ($\frac{\mathrm{10,628,020}\times 0.1832}{427+138}\approx \mathrm{3,447}<\mathrm{3,500}$). Twenty-five states are potential shortage states (95% CI: 24 to 27).

Figure 3.

NPPES – State Map of HHC Professional Shortage Areas in 2019

Notes: The map shows for each state the shortage area designation based on state population and the estimated workforce of either audiologists or all HHC professionals. Hawaii and Alaksa, not shown on the map, are a potential shortage state and no shortage state respectively.

Figure 4 displays a county-level map of shortage areas. Using 2019 localized estimates of hearing loss at the county level, when evaluated at the mean, 75.0% of counties are classified as shortage areas (32.9% of the US population), 10.6% of counties are potential shortage areas (22.1% of the US population), and 14.4% of counties are not shortage areas (45.1% of the population). The probability that a given county is a shortage area is higher than the national population-weighted probability, which illustrates that shortage areas are more common in less populated counties. Among the shortage counties, only 54.7% (95% CI: 50.7% - 59.5%) had at least one no-shortage neighbor, suggesting that residents of many counties do not have access to adequate HHC in either their own county or neighboring counties.

Figure 4.

NPPES – County Map of HHC Professional Shortage Areas in 2019

Notes: The map shows for each county the shortage area designation based on county population and the estimated workforce of either audiologists or all HHC professionals. Hawaii and Alaska not displayed. Of 3,143 counties in the United States, Rein et al (2024) provide estimates for 3,090 counties, which we classify as no-shortage, potential shortage, or shortage counties. We also identify 48 additional counties as shortage counties that do not have estimates in Rein et al (2024) but have population data available and no HHCs professionals practicing within the county. We are left with only 5 counties without a designation (no data) on the above map.

Appendix Figure A4 displays county-level maps indicating which counties experienced increases and decreases in HHCs per 100,000 population in 2018 compared to 2012. We use 2018 for these maps rather than 2022 because of substantial changes in Connecticut county boundaries after 2018. Overall, 169 counties without any HHC professionals gained at least one, while only 24 dropped to zero, indicating a slight increase in HHC dispersion leading up to 2019. Discussed further in the appendix, the majority of counties experiencing increases in HHC professionals per 100,000 residents had increases above 25%, whereas the majority experiencing decreases had decreases below 25%.

Discussion

Increasing access and affordability to hearing health care for adults is a major priority of the National Institute on Deafness and Other Communication Disorders (NIDCD).^24,25 Our study addresses research gaps identified by both the NIDCD and National Academies by providing a detailed national and county-level analysis of hearing health professional shortages, which can inform targeted policy interventions and resource allocation.

Using NPPES data, we find substantial growth in HHC professionals from 2012 to 2022, and note a higher growth rate among hearing instrument specialists compared to audiologists. The higher growth for hearing instrument specialists may be due to economic pressures to keep costs low. Primary care has experienced similar trends, with growth rates for primary care nurse practitioners, for example, greatly exceeding growth rates for primary care physicians in recent years.²²

Our NPPES HHC professional counts appear reliable. They are absent sudden unexpected changes and generally increase monotonically over time. NPPES audiologist counts are generally higher than other estimates of audiologists from other data sources, which may suggest those other data sources undercount audiologists.

One benefit of the NPPES data is that we can identify HHC professionals beyond just audiologists, and the NPPES data can be easily extended to other types of healthcare professionals who are required to obtain an NPI and have an identifying taxonomy code. Therefore, our methods provide a blueprint for other researchers aiming to identify counts of healthcare professionals and shortage areas, by area and over time. Other benefits include that the raw data is publicly available, free to use, includes granular location information down to the level of address, and is updated monthly.

The NPPES has some limitations. First, some circumstances could allow for the avoidance of registration in the NPPES, such as, according to the CMS, “a health care provider in sole practice who accepts only cash for payment.”¹⁴ The professional association, American Speech-Language-Hearing Association (ASHA), recommends that licensed audiologists have an NPI regardless of payments accepted, but some licensed audiologists may not follow these professional guidelines.²² NPPES estimates are likely more conservative for non-audiologist HHC professionals, such as hearing instrument specialists, since these individuals may be more likely to only accept private pay clientele. Unfortunately, we are unaware of any data on the share of HHC professionals that accept private pay only, but ASHA does provide information on the types of facilities that audiologists work at, which in turn have different probabilities of only accepting private pay for audiologists. Averaged across 2012–2023, this survey found that around 85 to 88 percent of audiologists work in non-residential or hospital settings, where insurance is likely accepted.²³ Only about 7 to 10 percent work in franchises or retail chains, where insurance is less likely to be accepted, and could serve as a proxy measure for potential missingness.

Second, while registrants have an obligation to maintain accurate records, this is not actively enforced through information verification by the CMS.¹⁴ In particular, we may observe HHC professionals exiting the workforce with a lag if they do not update their taxonomy code immediately to indicate they no longer practice, and instead wait for their licenses to expire. Third, the CMS makes the monthly dissemination of the NPPES publicly available; however, historic monthly disseminations are not provided by CMS. Researchers wishing to use NPPES data will therefore need to download the data each month to maintain access or otherwise locate archived versions of the database. Fourth, our study does not incorporate the supply of other HHC professionals, such as otolaryngologists, and is limited by the specificity of taxonomy codes. We rely on taxonomy codes for provider identification; however, if a particular service, such as cochlear implant programming or management, is rare but not distinguished by a unique taxonomy code, we cannot identify providers of such services. Lastly, a limitation of our approach is that it relies on an assumed benchmark for the number of individuals with hearing loss that a single HHC professional can adequately serve, rather than one derived from expert consensus specific to hearing care. In the absence of such guidance, we align with an established primary care standard and adjust it to the relevant population—those with hearing loss—as a pragmatic, if imperfect, proxy for identifying potential shortages.

Our research is consistent with other studies identifying urban/rural disparities in HHC.^26–29 Increasing the supply of HHC professionals, and encouraging these professionals to practice in rural communities in particular, could increase access, improve hearing-related outcomes, and benefit overall quality of life.³⁰ One potential solution is to provide financial incentives for students pursuing careers in audiology, particularly those willing to serve in underserved areas. The National Health Service Corp Loan Repayment Program provides loan repayment assistance for licensed eligible providers to serve at least two years in a health professional shortage area, but audiologists are not currently considered eligible providers.³¹ Additionally, NIH involvement to relax constraints on faculty, facilities, and clinical training opportunities would help increase the workforce overall.

Other policy options to improve the delivery of HHC in rural areas includes increasing funding for pilot implementation programs that focus on integrating hearing screening and referral networks within community health centers. Two recent programs, Baltimore HEARS and Connexiones,^35,36 both leverage community/university partnerships to deliver high-quality, community-based HHC. Other options include increasing reimbursement rates for community health workers and telehealth audiology services, and permanently extending the temporary allowance for the CMS to reimburse for telehealth audiologist visits that expire at the end of September 2025.³⁷

Another potential strategy for filling gaps in HHC access is virtual assessment and direct-to-consumer hearing device dispensing. Numerous validated online hearing tests are available that do not require professional administration or special equipment outside of a stable internet connection and a smart device or computer.³² Further, recent legislation allowing for a class of OTC hearing aids³³ now allows patients to self-manage moderate hearing loss from assessment to treatment without ever setting foot in a clinic.³⁴ These direct-to-consumer service models have demonstrated similar benefits to standard, in-office HHC.