Traveling wave generation using acoustic black holes

This work examines the effectiveness of acoustic black holes in generating non-reflective traveling waves from a single excitation source across a wide frequency range. This is inspired by similar observations in the basilar membrane of the mammalian inner ear. An aluminum beam is machined to introduce a gradual, asymmetric power-law taper at one of its ends. This tapered termination was then partially covered by viscoelastic tape to enhance the acoustic black hole effect in the system. This setup is then used to validate a model developed based on the Euler-Bernoulli beam theory. Given good agreement between the model and the experimental results over the frequency range [1 kHz , 10 kHz ], the model is used to conduct a parametric study to investigate the effects of different variables on the system’s response. This study revealed the effectiveness of acoustic black holes in sustaining traveling waves over a wide frequency range. By optimizing parameters, such as the power-law order, one can significantly enhance this effect. This is especially noticeable towards the lower-frequency end.