The Applied Acoustics Laboratory operates across several key areas of acoustics, providing both research and applied services. All the activities described below can also be performed on behalf of companies, industries, and public institutions for consultancy, design support, testing, and compliance verification.
Activities in this field include sound level measurements and subsequent analysis aimed at verifying compliance with regulatory limits, both indoors and outdoors.
In addition to measurements, advanced numerical modelling is often developed. Starting from the sound power levels of the sources and the geometric and orographic characteristics of the site, these models allow prediction of sound pressure level distribution in surrounding areas.
The Applied Acoustics Laboratory course was established to provide future engineers with the fundamental tools needed to understand and manage noise and vibration issues.
Instrumentation:
4 Class 1 sound level meters
SoundPLAN simulation software
Ambisonics system for sound source localisation
This area encompasses activities related to sound propagation within enclosed spaces.
The acoustic behaviour of an environment is assessed through measurements or simulations based on extensive material property databases. When sound power levels are known, it is also possible to estimate sound pressure levels at any point in the space (acoustic mapping), either for prediction or verification purposes.
Results obtained indoors can also be used to estimate the noise impact of a structure on the surrounding environment, provided that the sound insulation properties of the building envelope are available.
Another key activity is the evaluation of acoustic quality. Parameters describing how suitable an environment is for its intended use are determined by measuring impulse responses at defined positions. In more advanced cases, techniques such as time-reversal mirror processing are used to reduce system distortions.
Instrumentation:
Class 1 sound level meters
Sound cards
Omnidirectional and figure-eight microphones
Omnidirectional sound source
Binaural acquisition system
Ramsete and SoundPLAN simulation software
Audacity software with Aurora plug-ins
Ambisonics system
Oculus Meta Quest
Livox lidar
This specialised field focuses on the sound insulation properties of complex and multilayered materials.
While empirical correlations exist for simple structures, advanced multilayer systems are still an active research topic. Recently developed hybrid methods combine accelerometer measurements on structures with numerical models, offering promising results.
Once the critical frequency is determined, the same measurements can be used to evaluate the efficiency with which a structure radiates sound into the surrounding environment.
Instrumentation:
Sound intensity probe
Single-axis accelerometers
Laser vibrometer
Impact hammer (PCB)
Shaker and amplifier
Impedance head
OROS OR36 multichannel analyser
Oros Sound Intensity software
MATLAB post-processing tools
Comsol Multiphysics
The diffuse-field absorption coefficient is a key parameter typically measured in reverberation rooms on large samples according to international standards.
At early design stages, a preliminary material selection can be carried out by measuring the normal-incidence absorption coefficient using an impedance tube. This approach is faster, less expensive, and requires only small samples (46–60 mm in diameter).
The sample is placed inside the tube opposite a sound source generating white noise. Microphones measure incident and reflected sound, allowing calculation of the absorbed fraction.
Instrumentation:
2-, 3-, and 4-microphone impedance tubes
1/4" microphones
OROS OR36 multichannel analyser
B&K PULSE analyser
Flow resistivity test bench
Porosity test bench
Post-processing software
These activities focus on verifying compliance with building acoustic requirements, including façade insulation, airborne sound insulation, and impact noise (tapping noise).
Instrumentation:
Class 1 sound level meters
Omnidirectional sound source
Façade measurement source
Tapping machine
The laboratory is equipped to measure the sound power level of sources using:
Pressure-based methods (ISO 3744 and ISO 3746)
Sound intensity methods (ISO 9614 series)
Instrumentation:
Class 1 sound level meters
Brüel & Kjær sound intensity probe
OROS OR36 multichannel analyser
Oros Sound Intensity acquisition and post-processing software