Low Hearing. High Classroom Impact.

Posted by David Parish, Ph.D., CEO Calypso Systems
Wednesday June 24th, 2009 | 0 Comments

Years ago I was involved in scientific research on the effect of vision loss on the everyday tasks we take for granted, such as reading and walking around. After finishing my graduate work at NYU, I moved to Minnesota to join an esteemed research facility known as the Laboratory for Low Vision Research, run by a brilliant scientist named Gordon Legge, who himself had extremely "low vision". The term "low vision", used to describe a state of visual impairment that falls somewhere between normal (corrected) and blind, jumped to mind as I read through a research paper entitled "Classroom Acoustics and The Benefits of Sound Field Amplification", by Deborah Brace, an audiologist and speech therapist at Egg Harbor Township High School in New Jersey. It occurred to me that the term "Low Hearing" perfectly described the conditions addressed in the paper.

Deborah's paper is a very useful compilation of relevant research and includes her recommendations for mitigating the effects of low hearing in the classroom, whether the result of a physical impairment, external noise, a soft-spoken teacher or some combination. If you're in the business of designing, building, supporting or using classrooms, it's well worth 20 minutes of your time to read through it. A few details, however, really jumped out for me.

Looking at auditory properties of classrooms, there are two standards organizations, ANSI and ASHA (American Speech-Language-Hearing Association), that each offer guidelines for acceptable classroom background noise, 35 dB and 30 dB respectively. Several studies cited in the paper report unoccupied classroom noise levels that are consistently above these standards, often hitting the 60 dB range. HVAC, for example, can easily add 10-15 dB, while a fish tank can add 20-30 dB, all of which makes it more difficult for the teacher to be heard. Indeed, both standards group agree that classrooms should provide a signal-to-noise ratio (SNR; a comparison of the teacher's voice to the background noise level) of +15 dB or greater. Yet studies have shown classroom SNR that range from +5 dB to -7 dB, placing a strain on both students and teachers.

So - classrooms can be noisy places and it's no real surprise that students who hear the teacher more easily and clearly do better. The surprise for me was the magnitude of the impact of the combination of poor SNR and moderate hearing loss. While the paper offers up several useful and interesting examples, the absolute show-stopper was a reference to a research study by Nelson & Soli (2000) that reported:

• 13-15% of school age children studied had hearing losses of 15 dB or greater
• these students were typically unaware of their hearing loss
• these students were 10x more likely to repeat at least one grade as compared to their normal hearing peers

Anything that produces a negative learning outcome that is 10x below what we consider to be "normal" sounds like an epidemic to me. Add to that the increased likelihood of some of these students moving into special education programs, with it's attendant costs and consequences, and it may not be an over-reaction to call it a crisis.

Fortunately, there is no mystery to the solution required to turn the situation around. Classroom sound reinforcement is easy to install, easy to use and is even becoming easy to afford. Amplify the teacher's voice to dramatically improve the classroom SNR, regardless of whether the noise is internal, external or the result of low hearing, and the issue goes away. It's rare that we get to connect the dots between classroom technology and improved learning outcomes so directly. I look forward to seeing longitudinal studies that track the long term impact of classroom sound reinforcement as these systems become pervasive in all schools.