The Desirable Classroom Acoustics Imperative

This post is wrtitten  by my good friend Joseph Smaldino. Dr. Smaldino, who received his PhD in audiology from the University of Florida, is a Professor Emeritus at the University of Northern Iowa and is currently a Professor of Audiology in the Department of Communication Sciences and Disorders at Illinois State University.  His research areas are hearing aids, speech perception and audiologic rehabilitation, but he has focused for the last 20 years on the effects of classroom acoustics on listening and learning.  He served on the American National Standards Working groups that developed and subsequently revised a national classroom acoustic standard in 2002, 2009, and 2010. He has published extensively in the area and is a long-standing advocate for desirable classroom acoustics and acoustic accessibility. He is the current Editor of The Volta Review one of the oldest research journals in the area of hearing.  He has won a distinguished scholar award, has been a Fulbright Research Scholar in Poland, and in 2011 received the Mauldin Award for individuals who have demonstrated unsurpassed dedication to excellence in education and professionalism in the hearing health care industry and who have unselfishly given back to the profession, the community, and the hearing impaired. 

 The Goal is Desirable Classroom Acoustics

The classroom is an environment in which accurate transmission and reception of speech between teachers and students are essential for effective listening and learning to occur.  Undesirable room acoustics can degrade the quality of the speech signal, making education more difficult for many children.

We know that several acoustic elements of classrooms determine the adequacy of the speech signal received by the student. One of these elements is the signal-to-noise ratio (SNR) of the teacher’s speech (the signal) received by the student and the other is the long-duration reverberation time (RT) of the room. The SNR refers to the relative intensity of the teacher’s speech compared with the level of any background noise in the classroom as measured at the location of the student. Reverberation time (RT) refers to the length of time a signal persists in a room after the original signal has ended.

Research has demonstrated that inappropriate levels of classroom noise and/or reverberation can compromise not only speech perception, but also reading scores, spelling ability, behavior, attention, and concentration in children with normal hearing. It is even more deleterious to children with hearing loss or children who are at risk for listening and learning problems.  Professionals have been aware of the impact of acoustics on speech perception for some time (see Smaldino and Flexer, 2012 and Crandell, Smaldino, & Flexer, 2005 for a review of these studies).  It was not until 2002, however, when the ANSI S12.60 document entitled “Acoustical Performance Criteria, Design Requirements and Guidelines for Schools,” established the first voluntary targets for acceptable classroom acoustics.  These targets were set at 35 dBA for background noise and 0.6 seconds for reverberation time for a typical sized classroom.  These targets were generally upheld in the revision of the standard (ANSI/ASA, 2010).  Compliance with the standard remains voluntary.

What Responsibilities Do Audiologists Have?

In order for desirable classroom acoustics to become a universal reality for children in the schools, it is imperative that audiologists recognize the important roles they have to play:

Advocate and Educate

Generally, the impact of acoustics on classroom education is unappreciated or ignored by administrators during classroom construction and renovation. Anderson (2004) gives four reasons for this situation: (1) Adults with mature auditory-linguistic systems do not experience the same difficulty listening in a degraded environment as children with immature systems; (2) unfamiliarity with database of information regarding the impact of acoustics on learning; (3) belief that only children with hearing loss require good acoustic environments; and (4) ignorance of health consequences to teachers and costs to the school.

Audiologists who work in schools, have a responsibility to actively educate administrators and to advocate for classroom environments in which students can learn. Audiologists can bring the importance of classroom acoustics to the forefront by:  (1) developing primers on the impact of acoustics on education, (2) identifying themselves as experts and resources concerning room acoustics, (3) actively disseminating information about room acoustics to school administrators, the public, and policymakers.

Conduct a Classroom Acoustic Survey

Audiologists are typically the first professionals to identify at-risk populations or situations. Educational audiologists have long assessed classroom acoustics and student performance within their learning environments. The publication of the ANSI standard specifies specific acoustic measurement procedures to determine background noise and reverberation, and audiologists are uniquely positioned to take these acoustical measurements in the classroom and compare them to the standard.

Nowadays, estimates of physical acoustic conditions can be conveniently and inexpensively performed using smartphones and appropriate measurement software.  See Smaldino and Ostergren (2012) for a description of this technology.

Modify the Acoustic Conditions

A clear and complete speech signal greatly facilitates the development of oral expressive language and reading skills, so improvement in the speech-to-noise ratio and reverberation must be made across all of a child’s learning domains that do not comply with the ANSI criteria (Anderson, 2004). Audiologists can identify undesirable acoustical conditions and recommend improvements. Consultations with a room acoustics expert can provide recommendations for physical modification of the classroom environment.  Such a consultation is wise, because all possible physical acoustic modifications should be employed in order to maximize the advantages offered by other technologies frequently recommended by audiologists.

Hearing Aids and Classroom Audio Distribution Devices

For children with hearing loss, proper fitting of hearing aids is often a first step. However, hearing aids are not designed to deal with all listening needs. The biggest limitation of hearing aids is their inability to make the details of spoken communication audible when there is competing noise, when the listener cannot be close to the speaker, or when both conditions coexist. Hearing Assistive Technology (HAT)  is a term used to describe a range of products designed to solve the problems of noise, distance from the speaker, and room reverberation or echo that cannot be solved with a hearing aid alone (Boothroyd, 2004; Boothroyd, 2012). These products include a personal FM unit or installation of technology, such as classroom audio distribution (CAD) systems, that enhance the signal-to-noise ratio.

CAD technology allows control of the acoustic environment in many classrooms, thereby facilitating acoustic accessibility of teacher instruction for all children in the room (John, Kreisman and Smaldino, 2012; Crandell, Smaldino, & Flexer, 2005). A CAD system can be FM radio signal based or infrared signal based and looks like a wireless public address system, but is designed specifically to ensure that the entire speech signal—including the weak high-frequency consonants—reaches every child in the room.

Response to Intervention

More and more schools systems are incorporating principles of inclusion and response-to-intervention (RTI). Inclusion refers to the practice of placing children who previously would have been educated in self-contained classrooms into mainstream classrooms, where they require a good acoustical environment. RTI modifies instruction for struggling students to help them improve performance and achieve academic progress.

To meet the needs of all students, the educational system must use its collective resources to intervene early and provide appropriate interventions and supports to prevent learning and behavioral problems from becoming larger issues (Butler & Nelson, 2005). CAD systems offer a way of enhancing the classroom learning environment to facilitate inclusion and response-to-intervention.

Establish Efficacy of Improvements

Classroom modifications to improve listening and learning must be validated. Validation can be accomplished with pre- and post-modification physical acoustic measurements, behavioral report inventories, speech recognition tests, or other classroom performance measures. Any acoustical improvement undertaken must be documented to demonstrate that improvements persist over time.

Audiologists also have a number of behavioral inventories, such as the SIFTER (Anderson, 1989), the LIFE and the LIFE-R  (Anderson & Smaldino, 1998; Anderson, Smaldino and Spangler, 2012 ), or the CHILD (Anderson & Smaldino, 2001); speech recognition inventories (spondaic words and sentences); and classroom performance measures (on-task behavior measures, achievement test scores) that can be used to demonstrate the link between acoustic conditions and actual behavioral performance of students in the classroom.  A review of studies using behavioral measures can be found in Smaldino and Flexer (2012).

Provide Interventions

The behavioral and psychological effects of trying to listen and learn in a poor acoustic environment may linger on even after the physical acoustic inadequacies have been addressed. Physical and/or technological acoustic improvements alone may not be enough, and additional intervention is often necessary to implement a comprehensive approach to removing all of the listening and learning barriers produced by poor room acoustics. Some (re)habilitation interventions include listening training in the classroom and/or home, use of clear speech, phonological awareness training, visual communication training, communication repair strategy training, or auditory training.

Educating Stakeholders about Classroom Acoustics

A useful educational tool for teachers, parents, and administrators was developed by Smaldino in 2006 as part of a Teacher Quality Enhancement Grant through the College of Education at Northern Illinois University. The self-instructional, multi-media module, “Classroom Acoustics: Importance to Successful Listening and Learning,” covers the basic principles of room acoustics, the impact of acoustics on children and teachers, and acoustics standards, and provides suggestions for classroom improvements, from least to most expensive. The module, available online, has proven to be a very effective means for audiologists to educate stakeholders about classroom acoustics.


The importance of providing a high-quality speech signal for classroom listening and learning for all children is well-documented. Recent standards and guidelines have provided acoustic criteria and offer suggestions for how audiologists and can promote implementation of the standards. We must all work to make good classroom acoustics a norm in our schools—it is an acoustic impetrative!



American National Standards Institute/Acoustical Society of America (S12.60-2002). Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools. New York: American National Standards Institute.

American National Standards Institute/Acoustical Society of America (S12.60.2010). Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools, Part 1: Permanent Schools, and Part 2: Relocatable Classrooms Factors.

Anderson, K. (1989). Screening instrument for targeting educational risk (SIFTER). Tampa, FL: Educational Audiology Association. Click link for free download.

Anderson, K., & Smaldino, J. (1998). The listening inventory for education: An efficacy tool. (LIFE). Click link for free download.

Anderson, K., & Smaldino, J. (2001). Children’s home inventory for listening difficulties (CHILD). Click link for free download.

Anderson, K. (2004). The problem of classroom acoustics: the typical classroom soundscape is a barrier to learning. Seminars in Hearing, 25(2), 117-129.

Anderson, K., Smaldino, J. and Spangler, C. (2012).  The Listening Inventory for Education-REVISED:  An Efficacy Tool.  Click link to download.

Boothroyd, A. (2004). Room acoustics and speech perception. Seminars in Hearing, 25(2), 155-166.

Boothroyd, A. (2012).  Speech Perception in the Classroom in in Smaldino & Flexer (Eds).  Handbook of Acoustic Accessibility.  New York:  Thieme Medical Publishers.

Butler K., & Nelson, N. (Eds.). (2005). Responsiveness to intervention and the speech-language pathologist [Special issue]. Topics in Language Disorders, 25(2).

Crandell, C. C., Smaldino, J. J., & Flexer, C. (2005). Sound-Field amplification: applications to speech perception and classroom acoustics, 2nd ed. New York: Thomson Delmar Learning.

John, A., Kreisman, B. & Smaldino, J. (2012).  An Overview of Current CADS Technologies in in Smaldino & Flexer (Eds).  Handbook of Acoustic Accessibility.  New York:  Thieme Medical Publishers.

Smaldino, J.& Flexer, C. (2012).  Handbook of Acoustic Accessibility.  New York:  Thieme Medical Publishers.

Smaldino, J. and Ostergren, D. (2012).  Classroom Acoustic Measurements in Smaldino & Flexer (Eds).  Handbook of Acoustic Accessibility.  New York:  Thieme Medical Publishers.

Smaldino, J. (2006). Classroom acoustics: importance to successful listening and learning. Project REAL (Rockford Educational Alliance).


About Jane Madell

Jane Madell has a consulting practice in pediatric audiology. She is an audiologist, speech-language pathologist, and LSLS auditory verbal therapist, with a BA from Emerson College and an MA and PhD from the University of Wisconsin. Her 45+ years experience ranges from Deaf Nursery programs to positions at the League for the Hard of Hearing (Director), Long Island College Hospital, Downstate Medical Center, Beth Israel Medical Center/New York Eye and Ear Infirmary as director of the Hearing and Learning Center and Cochlear Implant Center. Jane has taught at the University of Tennessee, Columbia University, Downstate Medical School, and Albert Einstein Medical School, published 5 books, and written numerous books chapters and journal articles, and is a well known international lecturer.