Expert Interview: Prof. Astolfi and the Italian school acoustic standard (UNI 11532-2)

Professor Arianna Astolfi’s tireless work within the field of architectural acoustics culminated in the publication of the Italian acoustic standard for schools, UNI 11532-2. This standard broke new ground in 2020 by including an expanded set of acoustic parameters ensuring optimal communication and speech perception in the classroom. Following the standard is now a legal requirement for all public school buildings in Italy, including the one the Astolfi family’s children attend in Arianna’s hometown of Turin.

We interviewed her to learn more about how she accomplished the goal of creating a better sound environment for the children of Italy. But this victory transcends national borders by having a global relevance. In addition to directly enhancing the learning and wellbeing of those that Arianna cares about most, this scientifically-grounded standard also provides a road map of acoustic recommendations for the rest of the world to follow.

How did you find your way to the field of acoustics initially?

When I was a postgraduate student in the 1990s, acoustics was not considered very important. I studied building physics at the Polytechnic University of Turin, and my research focused on environmental comfort more broadly – not only sound but also lighting, indoor air quality, and ventilation. I wanted to know how those aspects impacted on the sustainability of buildings. After that I began to focus mainly on acoustic comfort, because, of course,

acoustics is equally as important as lighting or air quality, and perhaps even harder to get right. If you are cold you can put on another piece of clothing, or open a window if you are hot. But in the case of acoustic comfort, it is very complicated to change the room to make it more comfortable.

What led you to focus mainly on educational environments in your career?

When my children were in the first grades of school, they complained a lot to me about the difficulties they had in listening to the teachers. The classroom soundscape was terrible and it confused them during lessons.

I know that in Turin, as in the rest of the world, we have many old buildings that were designed without thinking too much about how the environment affects occupants. So I started to ask the teachers about the problems they encountered every day, at first as a concerned parent. They invited me to attend lessons with them so that I could understand better – you really can’t understand the situation unless you are actually in the environment.

I found that it was very stressful to attend lessons in primary school or kindergarten because the acoustics were so bad. So what led me to this field was really my experience of being a parent and wanting the best conditions for my children to learn in, but also from direct experience of sound in those learning environments and the challenges teachers were facing every day.

After that I pursued the topic as a researcher. I assessed the sound environment in fifty-one secondary-school classrooms and looked at how this influenced students’ performance and concentration. Interestingly, we found that student talking in the classrooms was the most disturbing noise source and that intermittent noises like footsteps were more disturbing than constant ones. This led to a highly cited publication in classroom acoustics in 2008.

How did you move towards more directly influencing sound environments in schools and developing the standard?

Initially I began to work with the province of Turin on a project to survey and in some cases assist in renovating schools in the region. The important thing was to have data taken from the real world and not just another laboratory study.

We also launched the I LISTEN (IO ASCALTO) project, which aimed to help children with dyslexia cope with their condition through better acoustics. There is a strong theoretical background for this link between dyslexia and auditory processing in the brain, producing a mismatch between the rhythm of speech and their neural firing. So we think there’s strong reason to believe that improving the sound environment as well as auditory training should help with dyslexia.

I also started to work on voice monitoring in teachers, because it was clear that the teachers I had spoken to were suffering a lot. So we developed a device that has been used to monitor vocal behavior during teaching, and we used it to find out more about which acoustic conditions are optimal for teachers’ speaking to be the least effortful.

We found that reverberation time is a compromise between speaking and listening. We found consistently across three studies that slightly higher reverberation times (around 0.75 seconds) were beneficial for the teachers when speaking. They felt it enhanced their voices.

Very low reverberation time can result in a lack of voice support from the room, but higher reverberation time than 0.75 seconds also added to the sound level in the classroom because of the Lombard effect, leading to an increase of noise inside the room. And this was not so good for either the teachers or the students. So it was about finding a balance between student listening experience and teachers’ vocal strain. In the end, the Italian standard recommends a reverberation time of about 0.56 s for a 60 m2 room, which is quite low but not so low that the teacher is uncomfortable. As I said, it’s a compromise.

The Italian standard also focuses on other parameters in addition to reverberation time. Could you tell me more about why you chose to include these?

Some of my research found significant relationships between speech clarity (C50) and reading speed in children. So I began to develop the scientific basis for including it in the standard, which is still evolving. Most standards focus on reverberation time, and we know that speech clarity is related to reverberation time. But speech clarity is directly acoustically relevant to the classroom situation because of the importance of good communication for learning, so we can’t ignore it like all other standards do.

Speech clarity is also related to the early reflections in a room, which directly influence speech, while reverberation time measurements ignore this part of the impulse response curve. So having reverberation time as the only parameter when assessing a classroom environment is not telling the whole story. We need parameters that consider early as well as late reflections in order to optimize learning environments sufficiently.

This standard is also the first to set maximum noise levels from outdoor sources and equipment, tackling environmental noise in the classroom. This needs to be measured during class time on week days in order to be verified. So it is a big task but important to do in order to limit noise from outside the building, which can lead to big effects within learning spaces.

How did you get this standard to become part of the building code in Italy?

Working with the Acoustical Society of Italy, we spent two years convincing politicians to look objectively at the science behind better indoor comfort in public buildings. Over time they became sensitive to these problems because they could see there was a strong evidence basis, and eventually they allowed the truth of the situation to influence public policy.

It was not easy, but we refused to give up! They eventually did recognize that it’s important for all the children at school to have this standard. It took 15 years to provide them with both evidence for the problem as well as the solution, but in the end it was a success.

Where to from here?

I will continue doing my best to solve the problems of acoustics in Italy, working closely with the Acoustical Society of Italy. I want to increase awareness of these issues enlarge the view of acoustics in Italy to include actors from industry as well as other fields of research.

To do this, I am currently arranging a conference on acoustics in Italy called Forum Acusticum, which will take place from 11th to 15th September, 2023, and I am inviting stakeholders from a variety of different contexts. Through this we intend to gain wider exposure for acoustical issues and also achieve resonance with the media. It is a very exciting time for acoustics in Italy.


To read some of Professor Astolfi’s publications, please see the full list here on ResearchGate.

For more information on the Italian Standard, please go to our article on Acoustic Bulletin here.


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