Stepped Standing-Wave Tube with Tapered Cross-Section

The acoustic dissonant properties of a stepped standing-wave tube with tapered cross-section (STTS) are studied. With the STTS, large-amplitude standing-wave fields are established by using an improved sound resource of loudspeaker under the excitations at the resonant frequencies of the 1st-order peak and trough. A large-amplitude standing-wave field of 185.9 dB is obtained at the resonant frequency of the 1st-order peak. Harmonic development are compared experimentally for the large-amplitude standing-wave fields obtained under the excitations at the resonant frequencies of the 1st- to 5th-order peak and trough. Meanwhile, waveform distortion of the fundamental waves are also compared experimentally. Under the same source-driving voltage, the SPLs of the fundamental wave excited at the resonant frequency of the 1st-order peak are much higher than the corresponding those excited at the resonant frequency of the 1st-order trough while for the waveform distortions, the opposite is true. The STTS provides a good approach to creating extremely nonlinear pure standing-wave field under the excitation at the resonant frequency of the 1st-order peak by using loudspeaker.