Near-field characteristics of the parametric loudspeaker using ultrasonic transducers

作者：Ju Hyeong Sick; Kim Yang Hann^*

来源：Applied Acoustics, 2010, 71(9): 793-800.

DOI：10.1016/j.apacoust.2010.04.004

• Parametric loudspeaker
• Near-field
• Directivity
• Attenuation
• Spurious signal

A parametric speaker is a device for generating and focusing highly directional sound beams. It is essentially a by-product that comes with the nonlinearity of ultrasound. It is noteworthy that this directional beam was controlled and utilized mostly for far-field applications in the past. We empirically study the directivity and attenuation characteristics of the parametric loudspeaker in the near-field where we desire to use it. Physical parameters for experiments are imported from a theoretical model based on the far-field approximation. The findings are that increases in aperture size and modulation frequency cause higher directivity, but have more than twice the beamwidth of the far-field approximation. The attenuation also does not obey the inverse-square law which describes far-field spreading from acoustic sources. The results conclusively explain a series of formation and attenuation of the virtual sound sources and define limitations of use in the near-field.

• 出版日期2010-9