1. Breif summary of the project and aims
In this project we will demonstrate in a first experiment how resonance has an effect on the harmony of the soundwe perceive. In the second part we will prove that a soundwave in physics can be described from a pure scientific point of view while the sound we hear, is an interpretation by our brain.
2. Material and assembly (including some medium-low resolution figures, diagrams or photographs)
We don’t need much material. 2 laptops to demonstrate resonance. The necessary software for frequency and amplitude regulation. We will show figures and diagrams notably of the sound waves on the laptop screens. We will bring all the necessary materials with us: Laptop x 2, oscilliscope, bluetooth speaker, microphone, cables, DB(A) meters.
3. Justification:
Physical principles involved and their relation to technological applications. We intend to observe the following phenomena
a. the resonance between the two laptops when they emit sound with the same frequency. This will be linked to pianos and to the fact that sound is a wave. We will also demonstrate that this resonance is only possible at certain phase-differences. We intend to observe the interference of waves of slightly different freqencies and thus establish the observation of interference giving rise to standing waves.
b. ultrasound and infrasound: this is in interaction with the public: we will start at a frequency too low to be heard bij the human ear and continue to a frequency too high to be heard.
c. we will produce sound waves with the same amplitude but different frequencies. This gives an idea of the interaction between purely sound physics and interpretation by the humain ear/brain
4. Performance and Results: Observations and Measurements
a) the qualitative measurement is the resonance as such, the quantitative is the frequency of the resonance. We will observe the frequency of the “la” used to tune a piano
b) interaction with the public leads to quantitave results “which frequencies are heard” and we can compare girls with boys, older adults (like the teachers) with young adults (the pupils)
c) demonstration of how our brain deceives us. Sound with the same amplitude but a higher frequency is conceived as louder. On the screen of the laptop we will see that it isn’t.
The screen on the laptop will give is quantitative data. Our ears will give us only qualitative (and intrinsically false) data.
5. Conclusions
a) Harmonic sound is important and can be measured in a physical experiment. What we consider “nice” when we hear it can be reduced to certain wound waves with the right frequency and in the right phase.
b) Not all sound waves can be heard. And those that can be heard, differ by age, gender, ….
c) Physics and biology do not always give the same result.
6. Bibliography
Trillingen en golven, nascholing Vliebergh-Scensiecentrum (KUL) 2008, M. De Cock www.roelhendriks.eu
Interactie 6.1 Methode fysica, Leo Van Echelpoel et al, uitgeverij die Keure, 2015, ISBN 978 90 4862 010 4
Leerboek kern, deel Krachten, trillingen en golven, Marleen Chalmet et al, uitgeverij de boeck, 2015, ISBN 978 90 455 5319 1
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