The Student Acoustics Seminar program traditionally features students from undergraduate, graduate, and doctoral levels who are interested in acoustics. It is a valuable experience for all the performers to practice how to perform in front of an audience and how to respond promptly to questions from the audience, where not only the lecturers, but also colleagues of the same age gather, who can, among other things, gain inspiration for their projects and theses. The audience traditionally includes members of the Czech Acoustical Society, which co-organizes the Student Acoustics Seminar, as well as practitioners. Students have the opportunity to meet representatives of companies and make important contacts in the field.
Students at the Faculty of Electrical Engineering of CTU can study acoustics, for example, at the Department of Radioelectronics or the Department of Physics. "Each department looks at acoustics from a different angle, focusing on different issues. Thanks to the Student Acoustics Seminar, we can learn from each other what research our colleagues are working on in the field," says Dr. Petr Honzík from the Department of Radioelectronics at FEE CTU.
Acoustic measurements in scale models of halls
In the last century, scaled models were widely used to design acoustic treatments for concert halls, cinemas, theatres and other spaces, where sound absorption and other important parameters were measured. Measurements in these models are gradually being superseded by software models. "However, scaled models are still relevant because they simplify the acoustic situation," said David Hromas, a student at FEE CTU, in his conference paper entitled Acoustic measurements in scaled models of halls.
"The main parameter of a scaled model is the scale, from this the relations for calculations of times, frequency and wavelength are derived. If the model is too small, we have to measure at high ultrasonic frequencies, where the sound absorption is high. The ideal scale is therefore 1:10 or 1:20," Hromas pointed out.
Measurements in scaled models are also unique in that you need to find a sound source that is capable of reproducing ultrasound, which is not encountered in conventional audio measurements in spatial acoustics, and a transducer. In the end, Hromas used a standard sound card to do this.
Room sound and music modelling software
As mentioned above, software models are more often used to predict the behaviour of sound in rooms. Gabriel Honzírek presented one such solution at the seminar. He is preparing it as his bachelor's project at FEE CTU and in the future it should work as an effective tool for companies. "Based on the model's prediction, customers will be able to compare the effectiveness of different treatments and choose the optimal solution that meets their acoustic requirements," Honzírek said.
He used two programs to develop the app. COMSOL Multiphysics, which enables modelling of rooms and their acoustic properties, and MATLAB, which he used for data analysis and processing. Honzírek's project will also include listening tests using real sounds, which will include speech, classical music and singing. Their role is to simulate sound in a real environment.
Acoustics is also sustainable
Another angle on acoustics was presented by a representative of the Faculty of Civil Engineering, namely PhD student Jiří Bečka, as part of an already varied programme. In his dissertation, he focuses on the topic of airtightness of lightweight partition walls in the context of sustainable development.
Up to one third of the waste produced is waste from building materials. The aim of the thesis is to find another use for this waste in the context of acoustics. One solution may be to replace traditional lightweight partition wall materials. These are mainly fillers such as mineral fibres or wood fibres, which are difficult to produce.
"The good news is that we can replace mineral fibre or the popular wood fibre with other sustainable materials and we will not get worse acoustically, on the contrary, in some cases we will even get better," said Bečka, adding that the best results in sound absorption were achieved by cellulose (diluted printed material) and liapor with cellulose fibres.