August 22, 2004 | Written by: Benjamin Markham

Acoustic Comfort in Libraries

There is a wide range of acoustical quality among library spaces. The general public may assume that a good library is a “quiet” library, when in fact objectively low background sound levels in open library spaces often lead to subjectively uncomfortable acoustics. To better define the issues, it is useful to identify objective acoustic measures that correlate with students’ and administrators’ subjective responses to libraries. Based on the results of surveys conducted by consultants at Acentech Incorporated, the author proposes that a “comfortable acoustic environment” in a library is an environment that provides freedom from distraction; that is, casual conversation and other noises in the library do not distract users reading or studying in the library. “Freedom from distraction” can be quantified and measured in terms of Articulation Index (AI) or other metrics based on signal-to-noise ratio. In highly reverberant library spaces, Speech Transmission Index (STI) may be more correlative to subjective impression of acoustic comfort. In order to provide a comfortable environment acoustically, a library must have 1) appropriate levels of background sound, 2) a physical barrier between noise-producing and noise-sensitive sections, and 3) sufficient sound absorbing material in the space. Measured quantitative metrics support these conclusions. A preliminary version of this paper was presented at the 146th meeting of the Acoustical Society of America in Austin, Texas.



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