Hear you Go, more info than you wanted to Know:
Some of the Background Reasoning:
The American Speech-Language-Hearing Association (ASHA) recommends an appropriate acoustical environment for all students in educational settings. Therefore, ASHA endorses ANSI S12.60-2010 Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools (ANSI S12.60-2010) as the national building and design standards for classroom acoustics. It is well recognized that the acoustical environment in a classroom or other educational environment is a critical variable in the academic, psychoeducational, and psychosocial development of children with normal hearing as well as children with hearing loss and/or other disabilities (e.g., auditory processing disorders, learning disabilities, attention deficit disorders). Inappropriate levels of reverberation and/or noise can deleteriously affect speech perception, reading/spelling ability, classroom behavior, attention, concentration, and educational achievement. In addition to compromising student function, poor classroom acoustics may also negatively affect teacher performance and increase vocal pathologies and absenteeism. Thus, all educational settings have an incentive to develop acoustical conditions that meet national standards. For children with hearing loss and/or other disabilities, the acoustics of the proposed educational setting(s) should be considered and addressed during the determination of a child's educational needs and placement. Acoustical factors in a classroom include: (1) the level of the background (ambient) noise in the room; (2) the relative intensity of the information carrying components of the speech signal to the non-information carrying signal or noise (i.e., signal-to-noise ratio [SNR]); and (3) the reverberant characteristics of the environment. It is important to note that these acoustical criteria are essentially identical to the recently approved ANSI Standard on classroom acoustics. Additionally, ANSI S12.60-20102 provides acoustic guidelines for learning spaces greater than 20,000 ft3. It is imperative that all new construction adhere to the acoustical criteria indicated above and stipulated in ANSI S12.60-2010. The fundamental strategy for improving acoustics within existing classrooms is acoustical modification of that environment. Acoustical measurement and/or modifications of educational settings should be multidisciplinary in nature and conducted by trained qualified professionals, such as audiologists, architects, and acoustical engineers. It is important to realize that these acoustical criteria are considered minimal. Some students, for example those with hearing loss, may require further signal enhancement technology. For additional information on acoustical criteria and hearing assistive technology, see ASHA's Acoustics in Educational Settings: Technical Report and Guidelines for Addressing Acoustics in Educational Settings.
http://www.asha.org/docs/html/TR2005-00042.html
3.2.2 background noise. Sound in a furnished, unoccupied learning space, including sounds from outdoor sources, building services and utilities. For the purposes of this standard, background noise excludes sound generated by people within the building or sound generated by temporary or permanent instructional equipment.
3.2.2.1 interior-source background noise. Noise from building services and utilities. 3.2.2.2 exterior-source background noise. Noise from transportation sources, such as aircraft, vehicle traffic, or from other outdoor noise sources (e.g., lawn maintenance, playground activities, or industrial sources).
https://cdn-web.iccsafe.org/wp-content/uploads/asc_a117/ProposedChanges-08.pdf
