Conference_programme: 1: Absorbing materials
Lecture: Possibilities of verifying the parameters of the absorbing elements using the loudspeaker
Author(s): Bouzek Stanislav, Turecek Oldrich
Summary:
There are mainly two methods, which are used to verify the parameters of acoustic absorption elements. The first is measurement of absorption coefficient alpha in the reverberation chamber, second is measurement in impedance tube. Unfortunately, for prototype design, both methods have some disadvantages. If we already have access to the reverberation chamber, we need a relatively large amount of the sample to be tested, considering to chamber size. This may be quite costly for initial experiments in designing new elements. In the impedance tube, it is possible to measure only very small circular samples. Neither of the used methods is not very suitable for the testing of small area prototypes. The result of theoretical design of resonators is often inaccurate due to nescience of end correction exact value.\nBased on these reasons, an experiment was executed to examine the changes of impedance characteristics of the loudspeaker, if an acoustically absorbing element is added to its baffle. The experiment is based on the knowledge of the bassreflex baffle - using the appropriately designed Helmholtz resonator extended frequency band to low frequencies. This change is also evident in loudspeaker impedance characteristics. It was assumed, if the absorption element is based on the resonance principle, it will be reflected by changing the impedance characteristic of the loudspeaker. The effect of different speakers and the baffle design was examined in the experiment. The measuring method has been tested on several samples based on the resonance principle. The resonance frequency of the acoustic element was visible on the impedance characteristics for all tested samples.\n
Corresponding author
Name: Mr Stanislav Bouzek
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Country: Czech Republic
