sequence that no information is present at all; (3) al low subjects to suppose that the original information could be present but has been made inaudible ("hear through the noise") (Plomp, 1980). The third possibility is the one we briefly hinted at in our paper, where we said that this "possibility must not be excluded." The truth is, however, that we do not really know exactly what happens when noise is added to a si gnal; how, for example, would it provide "spectral continuity?" The fact that Ohde and Sharl's (1980) and our results are of the same magnitude could indicate that the effects caused by a time window or noise are the same, but it is too early to say that. We investigated the vibration of leaves of four plant species in a sound field using a laser-Doppler-vibrometer system. All leaves behave as linear mechanical systems when driven by sound and noise at sound pressure levels (SPL) of up to 100 dB re 20 µPa. The modes of vibration are complex in the investigated frequencies (O.S-S.S kHz}, and change with the orientation of the leaf in the sound field. The vibration velocities of the leaves varied between 10-' and 3X10-4 m/s, while the vibration velocity of the air particles is S X 10-3 m/s at 100 dB SPL. Although the amount of sound energy absorbed in this way by a single leaf is very small, this mechanism may anyhow contribute to sound attenuation by plants and plant communities, since the number of leaves of one fullgrown tree equals 2 X 1 O'.
Mendeley saves you time finding and organizing research
There are no full text links
Choose a citation style from the tabs below