noise was equivalent to a 2-month reading delay in the United Kingdom and a 1-month delay in the Netherlands” (Stansfeld et al., 2005, p. 1946). This outcome was consistent with findings from other studies on the effects of aircraft noise on reading comprehension. Because it was a cross-sectional study, the effect of long-term noise exposure to aircraft noise could not be measured. Socioeconomic status was not found to be a factor in the size of the effect, a finding that differs from findings of other studies. The study also found that aircraft noise was “not associated with impairment in working memory, prospective memory, or sustained attention” (Stansfeld et al., 2005, p. 1946).
Stansfeld et al. (2005) also looked at the effect of traffic noise on the children. The authors noted linear exposure-effect associations between exposure to road traffic noise and increased functioning of episodic memory, in regard to information and conceptual recall (Stansfeld et al., 2005, p. 1947).
Teachers who work in noisy classrooms must constantly raise their voices to be heard over various other sounds. Over time, this can lead to vocal fatigue and other voice problems. One study published in 1993 found that four out of five teachers who participated in the study indicated some problems with vocal fatigue (Gotaas and Starr, 1993). A 1995 study of populations in the U.S. workforce that rely on voice as a primary tool of their trade found that teachers constitute more than 20 percent of the voice-clinic load or five times the number expected by their prevalence in this segment of the workforce (Titze et al., 1996).
Finding 5: In regard to noise, acoustics, student learning, and teacher health, the committee has found the following:
Sufficient evidence exists to conclude that there is an association between decreased noise levels in schools and improvement in student achievement.
Although there is strong evidence that reduced noise levels are most important for younger children because they are still developing speech discrimination, additional research is required to more precisely define possible needs for control of reverberant sound for younger children.
Some available evidence indicates that teacher health, in regard to voice impairment, may be adversely affected by noisier environments, although the magnitude of the effect cannot currently be estimated as a function of exposure to noise.
Recommendation 4: To facilitate student learning, guidelines for green schools should include requirements to meet American National Standards Institute (ANSI) Standard S12.60, “Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools.”