Essential Acoustic Terms Every Architect Should Know
When designing spaces, architects and contractors frequently encounter acoustic challenges that impact functionality and comfort. Understanding key acoustic terms helps in making informed decisions about materials, layouts, and noise control. Below is a guide to the most important acoustic phrases every design professional should know.
1. Reverberation Time (RT60)
Definition: The time it takes for sound to decay by 60 dB after the source stops.
Why It Matters: Affects speech clarity, noise control, and ambiance. Short RT60 is ideal for offices and classrooms, while concert halls need a longer RT60 for musical depth.
2. Sound Absorption
Definition: The process of reducing sound reflections using soft materials.
Common Materials: Felt panels, mineral wool, acoustic foam, and carpets.
Application: Improves speech intelligibility and noise reduction in open-plan offices, hotels, and restaurants.
3. Sound Reflection
Definition: When sound waves bounce off hard surfaces instead of being absorbed.
Impact: Increases echo and reverberation, making speech harder to understand.
Solution: Use acoustic panels, baffles, or soft furnishings to control reflections.
4. Sound Transmission Class (STC)
Definition: A rating system that measures how well a material blocks sound from passing through.
STC Ratings:
Low (20-30 STC) – Speech is easily heard through walls.
Medium (40-50 STC) – Speech is audible but muffled.
High (60+ STC) – Excellent sound isolation.
Used For: Designing walls, doors, and partitions in offices, hotels, and residential buildings.
5. Noise Reduction Coefficient (NRC)
Definition: A number between 0 and 1 that represents how much sound a material absorbs.
NRC 0.0 – No absorption (glass, concrete).
NRC 1.0 – Full absorption (high-density felt, acoustic foam).
Why It’s Important: Helps in selecting the right materials for controlling noise levels.
6. Speech Privacy
Definition: The ability to keep conversations confidential and unintelligible to unintended listeners.
Key in: Open offices, healthcare facilities, corporate spaces.
Improved By: Sound masking, absorptive materials, and proper space planning.
7. Sound Masking
Definition: The use of low-level background noise to make speech less intelligible.
Example: White noise systems in offices and waiting areas to improve privacy and focus.
8. Acoustic Zoning
Definition: Designing spaces based on expected noise levels to reduce sound spillover.
Example: Separating quiet areas (meeting rooms, libraries) from noisy zones (cafeterias, collaboration areas).
9. Diffusion
Definition: Scattering sound waves to reduce echoes without removing energy from the room.
Used In: Concert halls, theaters, high-end meeting rooms for natural sound balance.
10. Decibel (dB) Levels
Definition: A unit that measures sound intensity.
30 dB – Whisper
50 dB – Office background noise
70 dB – Busy restaurant
90 dB+ – Loud factory noise (requires protection)