###Room 1
Room 1 is a room which has a specific function which contains a broad range of acoustic functions. It is a place for religious gathering. Through this it is a space which hosts a speaker/ceremony and an audience. This ceremony includes monologues, chants and music, which translates to 3 individual acoustic purposes.
The way the room responds to sound is very interesting. It is a classic example when one thinks of room acoustics.
In itself it is a very silent room. Sound penetrates from the outside, muffled. Especially Trams passing by are heard. As a product of the silence one can hear the rustling of peoples clothes as they walk about.
The room feels large, without a clear direction. It is like being in an empty hall. The room eagerly waits for you to speak and hums back to you when you do so.
It’s a live room that is quite boomy. It can quickly get muddy as the room is quite reverby. It’s dense and rich.
Middle
Back
It gets muddier the more distance is between the microphone and me.
###Room 2
Room 2 has a simple function. It’s an auditory, thus one person speaks to many in this room. It’s not a well done one.
It is interesting how it doesn’t work.
The HVAC system is really loud, noticeably when you enter. and with it there is a silent beeping, only noticeable when concentrating on it.
The room feels quite intimite, there is not to much reverb. There is a flutter-echo in the sidewards axis.
In acoustic slang the room is tinny, echoey and harsh
For the recordings I always spoke from the podium and set the microphone in different spots.
middle
front left
back left
back right
The HVAC is insanly loud.
Task 3
For this task I revisited both rooms and made measurements to try to find out the reverberation time of these spaces. I had the feeling that both had a recognizable reverb. I guessed the church to have 4 seconds and the lecture room 0.8 s. To activate the room, especially in the church I made a loud Whistle. After this I analyzed the audios in Audacity and calculated the RT(60) for Both rooms
This is the one from the church. after analyzing it the RT(60) came out to be 3.12 s. This was shorter than expected but still a very long reverb time. In the decay one can see repeating negative peaks, which could point to a slight echo.
This is the decay of the lecture hall. The RT(60) here is 0.67s. It was also shorter than guessed but not too much. Here no real echo can be read
In the second part I tried to simulate these rooms. As I didn’t have the absorption coefficients of each room, as well as the volume of the church I decided to try and calculate the mean absorption coefficient. In the church, I estimated the volume by multiplying the floor area, which is stated to be 360 m^2 and roughly guessed the height. After the whole calculation we get a mean absorption coefficient of 0.15. In the lecture hall we get a mean absorption coefficient of 0.27. Both seem reasonable.
Task 4
The current room accoustics of the room are quite bad. The measurements show a quite symmetrical decay as all receivers measure the same T30 for the same frequencies. The room can be described as live, slightly boomy, dense and muddy. With a T30 of 1.5-1.7 s over most frequencies it is a room with quite a long reverb time if not intended as concert hall. It also has quite a bad speech clarity. Receiver 3 has the best C50 but is also closest to the source, thus getting the most direct sound energy. Receiver 3 is the furthest away of the three and thus also has the least clarity. Comparing it with SIA 181/1 this room would only qualify to be an entrance hall / hallway.
Goal:
The intended use I propose would be a theatre. This would fall under category 1b in the SIA norms. This category describes uses where there is a clear source postition and a clear receiver position in the room and mostly one talking to many. Dependent on the Volume taken this would require a reverberation time of 0.727 s which is about a second less than the current state.
Design
The final design made the dimensions of the actual room smaller, resulting in a room with a volume of 360 m^3 which results in a reverberation time of 0.633 s according to SIA 181/1. The room is now divided into 3 parts. The entrance, the backstage and the stage with the audience. The entrance gets a simple treatment as in all wall surfaces are acoustic panels. This will give a stark contrast to the entrance hall from which the audience enters. As it is only an entrance space where one doesn’t stay in for a long time it can be a little too well insulated to create the contrast. As this room will clearly meet all standards the calculation was not done. The backstage is also not very important in terms of room-acoustics. Sound only should’t travel into the big room, otherwise no special treatment is needed. In the big room acoustics get important and interesting.
The room has a function, where there is one location speaking to many. Ths the stage, where most sound will be generated is built like a loudspeaker, with turned walls that are made out of wood, which reflects most of the sound out towards the audience. There the first reflections on the all and the ceiling are permitted and the acoustic panels start only half way of the wall, but continue to the end. On the ceiling beside a 20 m^2 surface of acoustic panels specifically tuned Helmholz-absorbers for low frequencies are installed. The back is left palain of absorbers, to support back rows with enough acoustic energy. Towards the window a combination of multiple curtains are responsible for absorption. In the front a curtain is used that lets sound pass, only taking care of the light. There the glass behind reflects the sound into the audience, mirroring the opposite wall. In the back section an acoustic curtain is installed. Lastly on the face of the stage drawn back curtains cover the side walls and underneath the stage there are some more tuned absorbersfor the lower frequencies.
Results:
With the Sabine Formula we can calculate an approximate reverb time for each frequency. The average reverb time clearly meets the requirements. Lower frequencies are a little over, but still in an acceptable range.
Bibliography & Files
https://www.acoustic-curtains.com/curtains/acoustic-curtains
https://www.acoustic-supplies.com/absorption-coefficient-chart
