Analysis of a wooden specimen's mechanical properties through acoustic measurements in the very near field.

This paper presents the method for prediction of some basic mechanical parameters of a wood specimen by using simple instrumentation. The standard acoustic method for assessment of modulus of elasticity using the impulse excitation is extended by using a recording in the very near field. In this way, visualization of vibration patterns of the analyzed sample was accomplished for all modes below 5 kHz. This enables detection of signals with a good signal-to-noise ratio over a wide frequency range which is then used for loss factor assessment.

Hair tension influence on the vibroacoustic properties of the double bass bow.

The possibility of identifying vibration modes of a double bass bow, with a non-contact measurement of sound pressure in the Very Near Field (VNF) was investigated. This paper shows the application of this cost-effective method for vibroacoustic testings of the bow. The spectra of generated tones do not give sufficient information about a particular bow, but its vibroacoustical behavior provides additional properties. The visualization for all vibration modes below 4000 Hz was achieved by using sound pressure scanning in a VNF. Differences in the vibroacoustical properties of a double bass bow with different hair tension were analyzed.