Sound waves reflect, and loosely speaking they reflect infinitely until they completely decay. Of course human ears can only hear a certain frequency range (around 20Hz -20kHz) so after a while we can't hear them. However, it is important to note the frequency range of human speech is approximately 300Hz - 3000Hz. To summarize and simplify many things, reflections for speech are generally a bad thing; reflections increase the energy build up in a room and cause the Reverberation Time (RT) to increase. A desirable RT is highly dependent on the function of the room; a general RT for speech settings (lecture halls, classrooms, and yes, COURTROOMS!!!) should stay within .3 - 1 second.
Speech Intelligibly (SI) is a measurement which determines how well words are understood by the human ear; it is exactly what the name suggests haha! One of the metrics used to determine SI is Speech Transmission Index (STI). STI is a scale from 0 - 1, 0 being unacceptable and 1 being excellent.
So let's review before the next part. We want an STI closer to 1 and an RT between .3 and 1 second. Here is what the results of my preliminary tests were. In these tests, many things were assumed to get to the "root of the acoustic problem!" Here are the results of Circle Room "A1"
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| The RT of a Circular room "A" |
Remember our speech range of 300Hz-3000hz, the RT in this range is well above our 1 second maximum. NOT GOOD!
So the majority of our speech is not even at .5. Remember we want close to 1! NOT GOOD!
A 3D distribution of the STI metrics on Circle Room A1
Notice all of the reflections in Circle Room A1. NOT GOOD!
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