Signal-To-Noise
Signal-to-noise
ratio is the measure used in science and engineering to compare the
level of a desired signal, to the level of background noise. In schools,
the signal is the teacher's voice, and the background noise is all the
interfering noise, including that created by chairs and desks scraping
on the floor. The signal-to-noise ratio (or speech-to-noise ratio,
referred to as SNR) is basically a number value assigned to describe how
much louder the teacher is over the background noise. For example, if a
teacher's voice is 65 decibels and the background noise (chairs,
heaters, students) is 55 decibels, the SNR is +10. In order for
typically-hearing students to understand what they hear, they require an
SNR of +15 decibels. At risk students, students with hearing loss and
English as a Second Language students need an even greater
speech-to-noise ratio. In a school classroom, spoken language is the
tool most often used. Typically 60% of classroom learning activities
involve verbal communication and interactions. Teachers lecture classes,
students ask questions, instructions are given. A learning environment
that facilitates clear communication is critical. SNR is particularly
important in classrooms because of it's effects on speech
intelligibility which involves not only the student's ability to hear,
but his/her ability to understand and process what is said.
Intelligibility increases when the teacher's voice is much louder than
the background noise. Classrooms need to be acoustically healthy to
allow all students full access to clear channels of communication.
Sources: The Institute for Advanced Classroom Hearing ClassRoomHearing.org American National Standard: Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools Caslpa.ca