Research on Deaf and Hard-of-Hearing Students: Challenges and Cautions

The issue


There is no shortage of assumptions made about the education of deaf and hard-of-hearing (DHH) students; however, there is a shortage of high-quality research that provides relevant information to parents and educators about the educational placements, teaching methods, and supports that improve DHH students’ learning and academic achievement. Determining what works for this population requires credible research on their characteristics, needs, and experiences, not assumptions and philosophical biases. Those interested in improving DHH students’ academic outcomes need to know how to evaluate research findings to assess quality and relevance to specific individuals or groups.

What we know and what we don’t know

Quality research is logistically challenging and costly. Furthermore, DHH students have a wide range of needs, strengths, and experiences, making research on this population even more challenging.

Most empirical studies fall into two types. Descriptive studies can yield useful information about students’ abilities, needs, perceptions, and experiences, as well as information about their environments such as classrooms, schools, and homes. Results from descriptive studies may show associations between factors (e.g., language of instruction and academic performance), but they cannot explain causality. Impact studies are designed to provide evidence on causal relationships between practices or programs and outcomes (e.g., by examining the difference in academic achievement between students receiving peer tutoring compared to similar students receiving typical instruction).

Both descriptive and impact studies are needed to fully understand students’ needs and capabilities and identify the experiences and supports that will help them reach their full potential. However, both types can be designed and implemented well or poorly, and all studies have limitations.

The Annual Survey of Deaf and Hard-of-Hearing Children conducted by Gallaudet Research Institute is one of the most frequently cited descriptive studies of DHH students in the United States. The Annual Survey generates important information about DHH students and their educational experiences; however, participants are not representative of DHH students across the U.S. (e.g., they are more likely to attend schools for the deaf and have profound levels of hearing loss relative to the U.S. DHH population). Interpretation of findings requires caution and an understanding of who was included in the sample.

We have been involved with large, national, descriptive longitudinal studies in the United States, including the Special Education Elementary Study (SEELS) for students aged 6 to 12 and the National Longitudinal Transition Study-2 (NLTS2) for students aged 13 to 16. The strength of these studies is that sample members were representative of students across the U.S. who were identified for special education services for a “hearing impairment.”1  The random selection of students from a wide variety of state-sponsored schools (e.g., schools for the deaf) and school districts from different regions of the country and of varying sizes and community economic conditions was fundamental to these studies’ ability to describe DHH students nationally.

Because of the large scope of SEELS and NLTS2, as well as the Annual Survey, the amount and type of information they provide is limited. For example, investigations of important constructs such as the quality of teacher-student communication, student engagement, and classroom social dynamics, often measured through observations, are generally not feasible in such studies. Typically, studies with smaller, targeted samples (e.g., from a small number of classrooms or schools) are able to collect data of this kind. Although these smaller studies can illuminate important issues in deaf education, their findings cannot be generalized to the larger and very diverse DHH population.

Whether research is descriptive or intended to evaluate impact, measuring complex human behaviors, events, and processes is challenging. Research measures need to be valid (they measure what they are intended to measure), reliable (variables are measured in the same way across participants and settings), and relevant to the research questions.

A significant gap in research on DHH students is evidence about effective practices for improving their outcomes. Well-designed impact studies in education, especially for a low-incidence group such as DHH students, are hard to find. This is largely due to the fact that until recently, the field of education did not have well-articulated or agreed upon standards for impact studies. This has changed in the last half decade. There are now rigorous standards for demonstrating the effect of educational interventions on outcomes.2  Since most studies do not meet these standards, claims that a particular practice is effective for DHH students should be treated with caution.


No single study can provide definitive answers about improving DHH students’ schooling and outcomes. Data from multiple studies of varying types and with different DHH subgroups are needed to draw sound conclusions. For any study, research consumers need to understand who was included in the sample, how subjects were selected, and how phenomena were measured. With a critical eye, educators, parents, and others can evaluate the quality of research findings and their relevance to DHH students with specific attributes and experiences and effectively use research to determine how to best meet students’ needs.


Posted on April 1, 2014 by
Debra Shaver and Jose Blackorby,
SRI International,Menlo Park, CA

  1. “Hearing impairment” was a federally defined category for students identified for special education services at the time of the studies.
  2. See for example, the U.S. Department of Education’s What Works Clearinghouse.

Further reading

Schirmer, B.R. (2001). Using research to improve literacy practice and practice to improve literacy research. Journal of Deaf Studies and Deaf Education, 6, 83-91. view details

Shaver, D., Marschark, M., Newman, L., & Marder, C. Who is where? Characteristics of deaf and hard-of-hearing students in regular and special schools. Journal of Deaf Studies and Deaf Education, 19, 203-219. view details

Spencer, P.E. & Marschark, M. (2010). Evidence-based practice in educating deaf and hard-of-hearing students. New York: Oxford University Press. view details