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The American National Standard on classroom acoustics (ANSI S12.60-2002) presents criteria for background noise in classrooms. The criteria in ANSI S12.60 do not apply to the noise from portable or permanent built-in equipment used during the course of instruction, such as computers, audiovisual equipment, and printers. ANSI S12.60 provides general guidance on the selection and installation of such equipment; however, the standard does not present specific recommendations for schools to purchase these products to ensure they meet acoustics needs. This paper updates the recommendations made in a NOISE-CON 2003 paper by the authors on an approach for ensuring that computers and instructional material are acceptable acoustically in classroom environments. Schools should use unambiguous purchase specifications based on product A-weighted sound power level criteria. Schools should then install and operate the equipment in a manner to minimize noise emissions—considering both location of products and students and special noise reduction techniques. This paper recommends a purchase specification format; product sound power criteria based on experience and existing environmental criteria; and procedures for installing and locating such equipment in the classroom to minimize noise.

This paper presents results of Phase 3 of the study of prominent discrete tones by the Inter Committee Working Group (ICWG) from Information and Technology Equipment (ITTE). Progress and earlier results were reported at INTER-NOISE 99, the 139th Meeting of the Acoustical Society of America, and INTER-NOISE 2000. Phase 3 is a round robin involving 40 signals (some from ITTE products and some artificial sounds), which were recorded and distributed to participants as .wav files. Each of several ITTE company laboratories determined the objective tone-to-noise ratios and prominence ratios of the signals and/or provided subjective ratings. The paper presents comparisons of the objective and subjective ratings from the different laboratories. The relative success of the two objective methods in predicting the subjective ratings is discussed, as are the underlying issues and recommendations of the task group.

The recently adopted Illinois Noise Pollution Control Regulations will control noises emitted from “property-line-noise-sources,” e.g., industrial facilities, business, and commercial establishments, etc. The comprehensive regulations contain two parts: the first part contains a “nuisance” provision, and the second part contains octave-band sound pressure level limits for property-line noise sources. For purposes of these regulations, land is classified into three categories according to use, which correspond to industrial, commercial, and residential uses. The numerical limits, which will apply to a given facility, are dependent upon the land usage of both the noise emitter and noise receiver. Impulsive sounds are regulated by A -weighted sound levels, while “prominent discreet tones” are regulated in terms of 1/3-octave-band sound pressure levels. More stringent nighttime limits will apply to new facilities which emit sounds to residential lands. Compliance times for existing noise sources range from one to three years, while new facilities must comply immediately. These regulations are the first step in a program designed to reduce noise pollution in Illinois-future regulations will control noises emitted from transportation sources and construction sources.

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