Room 1: Practice room

01 Acoustic Profiles

Room 1 is a practice room in the basement of our neighbours house. It’s about 4 by 3 meters big and has acoustic paneling all along the walls and the ceiling. The most prominent sound, if no one is playing, is the blood rushing through your own body. Besides that you can hear muted footsteps and voices from above.

Room 1 is used for saxophone playing and band rehearsals. I find it interesting because the panels on the walls and ceiling absorb most of the sound, making the space sound very dull and dead. Since the surfaces are so absorbant you can hear a rapid decrease in the volume of the different recordings even though the distances inbetween aren’t very big. The sounds of your own body build an ambient soundscape, while the footsteps, voices, and dishes clattering from above only interrupt shortly. Because they sound so dull, they feel much farther away than they are. The sound of my blood rushing through my head also made me feel quite uncomfortable and very enclosed in the space.

02 Characterization of room acoustic treatments

The whole room is covered in absorbers. Each wall and the ceiling are topped with acoustic foam panels, and the floor is carpeted. Only about 20 cm at the bottom of each wall, the door and a ventilation shaft are left open. The area of the foam panels is about 42 square meters, and the area of the carpet is about 12 square meters. The carpet is able to absorb sounds in the high-frequency range and the foam panels can presumably absorb mid- to high-frequencies.

Around the room, there is a bookshelf, a keyboard, a sofa, and a fake plant. They could slightly diffuse the sound, but there is very little reflection anyway. The bottom rim of the room that is left uncovered is probably the most sound-reflecting surface. The room acoustics themselves are not very enjoyable since the surfaces are so absorbant and serve the purpose of hearing as little as possible from the practice room in the rest of the building. Since the panels are white and flat they look similar to the white walls underneath, but you obviously notice the acoustic foam panels immediately upon walking into the room.

03 Empirical and numerical estimation of room acoustic properties

For assignment number three I chose the first room. I wanted to see how short the reverberation time actually is because the room is so dry.

I analysed the first clap and only used the 20 dB decay because everything after the first peak was rather quiet very quickly. The 30 dB decay takes 0.105 seconds. That corresponds to a reverberation time of 0.,315 seconds.

There aren’t any echoes visible in the impulse decay, which corresponds with the observations from the first two assignments.

I was not able to find fully suitable absorbers, but with the data I used the reverberation time at 500 Hz is 0.10 and at 1000 Hz it is 0.09.

Room 2: Hallway and Staircase

01 Acoustic Profiles

Room 2 is our hallway/ staircase. It has very high ceilings, and the stairs lead directly to the living room, kitchen, and entrance, all connected. The ceiling is also slightly slanted on both sides of the hallway. The most prominent sounds are the doors opening and closing, voices talking, and footsteps or office chairs rolling around. If you listen attentively, you can also hear the ventilation humming.

I remember walking out into the hallway when playing the violin, because I prefer the acoustics there. To me, the space sounds live and warm and quite open and lush, because it is so connected to the space below and has high ceilings. In comparison to room 1, the volume decreases much less with distance, but its clarity decreases because the surfaces are more reflective. The footsteps and pants swishing against each other while walking, as well as the doors opening and shutting, are the most catchy sounds, while the humming of the ventilation is more overheard. As I said, the more resonant space feels much more comfortable to me, especially when playing music. The openness also leads to me being able to hear people moving around, which I enjoy, because it makes the house feel more alive. Both the openness of the space and the more reflective surfaces in comparison to the absorbent panels in room 1 make me feel less isolated and enclosed.

02 Characterization of room acoustic treatments

There is a very thin curtain a few centimeters in front of one of the windows. The area is about 5 square meters big. The curtain can presumably absorb very high frequencies. Since it is a hallway and staircase there isn’t any furniture. The walls and ceiling are plastered and the floor is hard-wood. So all rather hard and sound-reflecting surfaces, but the plaster is rather rough and not fully smooth.

The ceiling of the space is very high, and the space is also connected to the lower floor through the staircase. Since nothing is separating the staircase from the rest of the house, theoretically, everything is connected if you leave the doors open, but my focus is on the red space highlighted above. The ceiling is slanted on the east side and is lower on the west side, leading to a niche on the west side of the hallway.

htly tilted at different angles towards the seating area.

04 Final Assignment

My intended use for the room is a concert and practice room for example for chamber music. This puts the room into the category 1a. The existing room is 13.5 m x 9.7 m x 4.8 m resulting in a volume of 630 m3.

With the equation above we can calculate the reverberation time resulting in about 1.33 seconds.

A = 0.163 · V / T_soll

Using Sabine’s formula for the surface of absorption we get 77.2 m2. However we have to take into account the ceiling being higher than 2.5 m.

A/V ≥ [3.13 + 4.69 · lg(h/1m)]⁻¹

With the formula above we get a minimum surface of absorption of 99.5 m2.

I know that I want to remove the suspended ceiling and fully cover one plasterboard wall so with that in mind I calculated the absorption area of each frequency before.

In one corner I want to add seating in the form of big stairs with a volume on the inside to tackle low frequencies. I also know that I want it to not be parallel to scatter the sound.

Above the performers I hanged reflective panels slightly tilted at different angles towards the seating area.

To compensate for taking out the suspended ceiling and to add some absorption on the ceiling I added thick curtains draped above the room.

On the other side across the seating area i made a triangular pattern along the wall to scatter the sound.

With all of the above made changes the absorption area is quite balanced but slightly below the minimum absorption area of 99.5 m2 that we calculated earlier. So I gave the option of a curtain along the glass facade that can be opened or closed depending on the usage of the room resulting in the two different scenarios below.

Here is a drawing of what it could look like.