ELG1 - INTRODUCTION TO BUILDING ACOUSTICS FOR ARCHITECTS AND ENGINEERS
Marcelo Blasco 2022-2023
CONTENTS
1. The basics
- Acoustic pressure, sound, dB, intensity, power
- Diffuse and direct sound field, reverberation
2. Airborne sound transmission
- SRI: Single, double constructions
- Sound radiation
- Sound transmission, sound insulation
3. In practice
- Façades
- Roofs
- Walls and floors
- Door concepts
- Technical installations
- Absorption
Acoustical regulation = national level (since 2022 new standards)
Good indoor climate can only be achieved by good sound insulation of glass parts & adapted ventilation
parts
IMPORTANT: find solutions for ac. problems in the design phase (structural materials are hard to improve
later). Factors to keep in mind: composition of the façade, type of glass, quality of sealings, ac.
characteristics of receiving room, type of incident noise & type and amount of ventilation devices)
MOST IMPORTANT: don’t confuse thermal insulation, acoustic insulation & acoustic absorption.
, CHAPTER 1: THE BASICS
Building Acoustics: sound transmission between spaces in one building/different buildings or sound travelling from
the outside to the inside or sounds travelling from the inside to the outside.
Sound: auditive perception of vibrations or waves that travel through air, liquids, or solids. It’s a slight variation of
air pressure (0.00002 Pa – 20 pa).
Frequency (f): amount of sound waves per second [Hz], the tone you hear.
Low F: long wavelength, deep tones, hard to block in acoustics (1000Hz)
High F: short wavelength, high tones, easy to block but air tightness is
important, can go through small holes (5000 Hz)
Sound pressure: The amplitude of a soundwave, the energy or volume of the sound [Pa]
Air borne sound VS. structure borne sound: AB: sound source excites the air; vibration then reaches the ear.
SB: sound source excites construction element directly. One source can generate both (piano on wooden floor)
Sound travels way faster in solids -> forces of molecules are higher, transmit faster. Celerity air c = λ*f = 340 m/s
Vibration propagation: when you connect solids, sound will transmit fast. Celerity c = 1400 m/s
What do we do? Decoupling of connections (floating screed) liquids
Celerity solids c = 5000 m/s
Transversal waves: particles go up and down (Mexican wave) (air & solids)
Longitudinal waves: particles move sideways, in the same direction as the wave (liquids & solids)
Frequencies in building acoustics: You can do measurements in different frequency
bands -> octave band: doubling of the f. with 3 bands in between. Low resolution of
measurements, less data (used in NL). 1/3 octave band: high resolution (used in BE)
- Range of standard test f. in building acoustics (100 Hz – 5k Hz)
- Range that is hard to measure but important for slow driving traffic,
industrial buildings & clubs (50 Hz – 80 Hz)
- Range of the human voice (500 Hz – 2k Hz)
- Ultrasound > 20 000 Hz (bats & dogs)
- Infrasound < 25 Hz (elephants & whales)
