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Audio-Visual
System Design


Loudspeaker
array case study


Sound System Design

Will that be one
mic or two?


Lavalier vs.
lectern mic


Speech Intelligibility

Classroom Speech
Intelligibility


Classroom Speech
Reinforcement


Classroom
Intelligibility and
Background Noise


Video Conference Facilities

Educational
Multimedia
Systems



Member of the
International
Communications
Industries
Association

Post-Secondary Education Facilities

UBC IRC5

Acoustical design of classrooms and lecture theatres is of paramount importance in meeting the required speech intelligibility rating for Post secondary educational facilities. In a facility intended for learning, new information is being delivered in such density that you can't afford to have marginal speech intelligibility. Poor acoustics will degrade speech intelligibility for people who have a common first language, but for people who are learning in a second language, the need for shorter reverberation time and lower background noise becomes even more important. The same stringent criteria also need to be applied to meet the requirements of disability access for the hearing impaired.

Many colleges and universities have been surprised to learn how poor the acoustics are in their existing facilities. We have participated in the measurement, analysis and subsequent design of acoustical upgrades of lecture rooms and theatres across Western Canada. It isn't just the 200+ seat lecture theatres that are a problem, it extends right down to the 30 seat classrooms. The problems can exist in buildings constructed from 1940 to now, as the acoustical elements that made classrooms work effectively were not always understood by room designers. At one time the belief was that a long reverberation time helped improve the level of speech, now it is known that early reflections arriving within the first 35/100 of a second can help improve speech intelligibility and level, but late reflections and excessive reverberation can degrade intelligibility. Excessive background noise levels from HVAC systems or exterior sources such as traffic will also seriously degrade intelligibility, even where the reverberation is suitable. Between these two important parameters of excessive reverberation and background noise, many classrooms and lecture theatres receive their failing grade.

Listen to these examples of speech in a lecture theatre with different reverberation times. The listening position is at the back of the classroom. These reverberation times are typical of the range found in many lecture theatres. The last sample is an example of a room designed to hearing impaired accessibility standards.

  • Lecture Theatre with 1.3 second Reverb time
    WAV (184kB) - RealAudio (41kB) - MP3 (35kB)

  • Lecture Theatre with 0.8 second Reverb time
    WAV (158kB) - RealAudio (37kB) - MP3 (31kB)

  • Lecture Theatre with 0.6 second Reverb time
    WAV (150kB) - RealAudio (35kB) - MP3 (29kB)

We also provide design for Audio-Visual support systems, and sound reinforcement systems to augment modern teaching methods and materials. The design of A/V systems must support the pedagogy of the faculty and instructors, without interfering with the lesson itself. Classrooms, lecture theatres, case study rooms and labs all have their own specific requirements for support materials and teaching methods. Even within the same faculty, the requirements will differ for various levels of instruction. We meet with the faculty to help provide a suitable A/V support system for the full range of teaching methods and styles. As distance education becomes more common in Universities and Colleges, there is greater demand for video based presentation systems.

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Mc Squared System Design Group, Inc Mc Squared System Design Group, Inc
323 - 901 West 3rd Street
North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181