1 Exploring Sound Qualities in Architectural Design
Living Science – My Kitchen
I live in a studio apartment with a bedroom and a kitchen that are separated by a door. The main reason I spend time in my kitchen is to brew my morning coffee with a small espresso machine, mix a smoothie using my loud Ninja blender, or prepare quick dinners in between study sessions.
Since I don’t use the kitchen table for studying or relaxing, the time I spend here is often filled with short bursts of intense activity—rushing around, banging pots and pans, or grinding coffee beans. That’s why I associate the kitchen with an “uncalm” atmosphere—sharp, sudden, and high in volume.
The two-minute process of brewing coffee is a recurring acoustic event in this room. Although the loud mechanical humming and hissing sound from the espresso machine is tolerable—partly because I associate it with the comfort of caffeine—it still adds to the overall noisiness of the space.
Listening closely to the recording made in the kitchen, you can clearly hear:
Whirring and pumping from the espresso machine
Dripping and gurgling from the coffee pour
The grind-like rattling from the portafilter being locked and unlocked
I would describe the kitchen as:
Live – because of the reflective surfaces: stainless steel countertop, tiled backsplash, bare floor
Tinny – due to the emphasis on high-frequency sounds bouncing off the hard cabinetry and metal
Echoey – short but distinct sound reflections are noticeable, especially when pans or dishes are moved
Occasionally Harsh – particularly when using the blender or opening and closing drawers rapidly
The kitchen is rectangular and compact, with hard vertical surfaces and minimal soft materials, which makes it quite reflective and noisy. It’s not a space with much acoustic confidentiality.
Living Science – My bedroom
In contrast, the bedroom—separated from the kitchen by a thick wooden door—acts as a calm buffer zone. I use this space for sleeping, working or reading. It’s where I spend the most time while being home. The geometry of the room isn’t strictly rectangular; it features slightly angled walls and vertical slits from the windows, which help scatter sound rather than reflecting it back directly.
The room is moderately furnished, with a bed, large desk setup, clothes rack, which all contribute to diffusing and absorbing sound. Listening to the coffee brewing from this room (with the door closed), I noticed how the buzzing and whirring of the espresso machine fades into the background, turning into a barely noticeable sound. That’s when I realized just how acoustically isolated this room is from the kitchen.
Acoustically, the bedroom feels:
Dead – the reverb is minimal, and sounds are quickly absorbed by the textiles and furnishings
Warm – sounds in this space feel cozy and contained
Quiet and discreet – you can hear faint noises from other rooms, but they’re muffled and softened
Balanced – speech and music are clear, but not exaggerated in any particular frequency range
Typical sounds in this room include:
Keyboard clacking and mouse clicks
The soft hum of the standing fan
Occasionally, a sound coming from the kitchen when used.
2 Exploring the Emotional Impact of Everyday Sounds
Sound of Nature vs. Aerodynamic Noise
I usually go to take a walk or a run in the Kappeliholzweiher forest in Hönggerberg to refresh my brain. For me it is a moment to get new air and refresh my brain. I never bring headphones to listen to music while running since i prefer to be in the moment while running and hearing the sound of nature. But unfortunately the airport of Zurich is so close and heavily trafficked, that the sound of nature always gets interrupted and accentuated by the aerodynamic noised of the airplanes that are in lower altitudes.
Running in Nature
The second recording is from me running in the Kappeliholzweiher forest in Hönggerberg when the sound condition are optimal and the aerodynamics noises aren’t noticeable.
This is when i am really enjoying being in the moment. The variety of bird sounds, the sound of each footstep while running, hearing the bouncy foam cushioning from my running shoes, confirms the responsiveness these shoes has and makes me feel faster.
3. Empirical and Numerical Estimation of Room Acoustic Properties
I recorded a hand clap in my bedroom and analyzed the sound in Audacity.
The sound dropped by 30 dB in 0.26 sec, so I estimated the RT60 by doubling that: RT60 = 0.52 sec. This means sound fades pretty quickly in the room, which makes sense since the bedroom has soft materials like a bed, clothes, and curtains that absorb sound and reduce echo.
4 The full picture
For this assignment, I analyzed the studio workspace of Tom Emerson at ETH Zürich. Because clear speech and acoustic comfort are essential in this setting, I focused on evaluating how well the room supports spoken communication and whether its current acoustic treatments are sufficient.
Room Dimensions and Volume
- Width: 8.2 m
- Length: 19.2 m
- Height: 2.9 m (average)
- Volume: 456.6 m³
Measured Reverberation Time (RT60)
A hand clap was recorded in the center of the classroom. Based on the waveform in Audacity, the sound dropped by 30 dB in approximately 0.60 seconds.
To estimate the RT60 (reverberation time until the sound fades by 60 dB), the decay time was doubled:
RT60 ≈ 0.60 s × 2 = 1.20 seconds
Estimated Reverberation Time (Sabine and Eyring)
Surface materials considered (excluding furniture):
| Surface | Area (m²) | Material | Absorption Coefficient (mid-freq) |
|---|---|---|---|
| Floor | 157.4 | Vinyl or sealed surface | 0.04 |
| Ceiling | 157.4 | Perforated acoustic panels | 0.60 |
| Walls | 158.9 | Painted plaster / gypsum | 0.05 |
Total absorption area A ≈ 108.7 m²
Average absorption coefficient α ≈ 0.23
Theoretical RT60 Estimates
Sabine RT60: 0.68 s
Eyring RT60: 0.60 s
Applicable Standards and Guidelines
– SIA 181/1: Target RT60 (T_soll) ≈ 0.61 seconds for this volume
– DIN 18041: Recommends 0.6–0.8 seconds for classrooms
– ISO 3382-1: For measuring reverberation time in performance spaces
Room Geometry and Acoustical Layout
The room has a rectangular layout with extended parallel walls and flat ceiling. Acoustic ceiling panels are integrated into the lighting grid, but walls remain untreated and reflective. The floor is hard and minimally absorptive.
Interpretation and Comparison
The measured RT60 of 1.20 s is nearly double the estimated values, suggesting possible underperformance of absorbers or uneven sound distribution. This affects speech intelligibility, especially in the rear of the room.
Suggestions for Improvement
– Add absorptive wall panels on the long sides to reduce flutter echoes.
– Introduce partial ceiling reflectors for better sound projection.
– Use mobile absorptive dividers to help balance the acoustic field.
5 Final Assignment
Room HIL B61
The aim was to measure how sound behaves in the room, compare it to official guidelines, and suggest simple improvements that would support both uses without changing the room’s layout or flexibility.
2. Room Description and Use
Based on measurements from the Rhino model and on-site observations, the room has the following dimensions:
- Length: 11.625 m
- Width: 7.345 m
- Height: 2.80 m
- Volume: approx. 239.3 m³
The space is arranged in two typical ways:
- In lecture mode, a speaker presents from the front corner while students sit in rows.
- In workspace mode, tables are grouped in the center and chairs are moved aside to allow movement around the room.
Although the room appears best suited for light model assembly work — such as gluing, measuring, and discussing projects — it is also sometimes used for louder activities, such as sanding. These tools generate continuous, high-pitched sounds that reflect strongly in the current room conditions.
3. Surfaces and Materials
From the Rhino model, photos, and observation, the following surface materials were identified:
| Surface | Material | Estimated Absorption Coefficient |
| Ceiling | Painted panels, visible lighting/pipes, partly treated | ~0.40–0.60 |
| Floor | Painted concrete or epoxy resin | ~0.03–0.05 |
| Walls | White-painted plaster/concrete | ~0.05 |
| Furniture | Wood tables, plastic/metal chairs | Reflective |
| Acoustic treatment | A few wall-mounted panels on one long side | ~0.40–0.60 (partial coverage) |
Overall, the room includes many reflective surfaces, especially at ear level. These cause sound energy to remain in the room for too long, making the space feel echoey and acoustically unbalanced.
4. Measured Reverberation Time (RT60)
To evaluate the reverberation time (RT60), I recorded a hand clap in the center of the room using a standard microphone and analyzed it in Audacity. The waveform showed a 30 dB decay in approximately 0.55 seconds.
Since this is a 30 dB drop (half of 60 dB), we estimate the full RT60 by multiplying the time by 2:
RT60 = 0.55 x 2 = 1.10 seconds
This result reflects how long it takes for sound to fade out in the room — which directly affects speech clarity and acoustic comfort.
5. SIA Standard and Target Value
According to SIA 181/1, a lecture space of this volume should have a reverberation time close to:
Recommended reverbation time = 0.32 × log10(239.3) − 0.17 = 0.59 seconds.
Compared to the measured value of 1.10 seconds, the room currently exceeds the recommended reverberation time by nearly double, which can make speech harder to understand and sharp noises (like sanding) more intense.
6. Frequency Considerations
Different frequencies behave differently in a space:
| Frequency Range | Description | Relevance to this room |
| Low (125–250 Hz) | Deep sounds (e.g. footsteps, bass) | Less of a concern here |
| Mid (500–1000 Hz) | Speech sounds (voice clarity) | Most important for lectures |
| High (2000–4000 Hz) | Sharp tool noise, consonants | Very reflective in this room |
Most human speech and the sharp sounds created during sanding or cutting fall in the mid to high frequency range. These are the frequencies that should be targeted by acoustic treatments.
7. Recommendations
To reduce the RT60 and improve acoustic comfort, especially during lectures, I suggest the following changes:
| Location | Suggested Treatment | Material |
| Walls | Add more acoustic panels along untreated wall | PET felt or mineral wool (50 mm = 0.85) |
| Ceiling | Fill gaps between light panels with absorptive baffles | Basotect® melamine foam 0.9 |
| Furniture | Install small fabric-wrapped panels under tables | Mineral wool with wooden frame |
| Flexible options | Mobile PET partitions | Allow reconfiguration based on use |
These suggestions are modular, reversible, and easy to install without changing the core structure of the space — which is important given the room’s flexible use.
8. Addressing Loud Tool Usage
One of the biggest challenges in this space is not just the reverberation, but the use of loud machines like sanding machince inside the room. These tools produce intense high-frequency sounds that reflect strongly in the current setup. I suggest that all loud work should be moved to the adjacent wood workshop, which is designed for that type of activity.
Keeping high-noise tools out of the room is just as important as installing absorbers. Reducing the sound at the source makes the space easier to manage acoustically.
9. Predicted Outcome
Using the 10log RT60 calculator, applying the recommended materials and surface areas should lower the RT60 to:
RT60 = 0.6 seconds
This matches the target and would significantly improve:
- Speech clarity in lectures
- Acoustic comfort during group discussions
- Noise control when multiple people are working in parallel
10. Conclusion
The current acoustic performance of the Raplab workspace does not meet the standard for a multipurpose lecture and working environment. The reverberation time is too high, sharp sounds reflect too easily, and tool noise is not well managed.
By increasing absorption on walls and ceilings, installing light under-table treatments, and moving noisy work to the main workshop, the room can become both a clearer lecture space and a calmer, more productive workspace — all without compromising its flexibility.
