High-intensity focused airborne ultrasound fields are increasingly applied in various technical fields, for example, to generate haptic feedback during gesture interaction. Reliable measurement data of sound pressure levels are required to assess potential health hazards to users. Such ultrasound fields pose special challenges for a quantitative characterization. The high sound pressure levels in combination with the higher harmonics generated by nonlinear effects require both a high upper limit of the level linearity range and a wide bandwidth of the measuring chain. Furthermore, small wavelengths and the focusing result in spatially strongly varying sound fields. In the present case, a 40 kHz signal was focused on a single point using a transducer array. Different microphone types were investigated with respect to their suitability for measuring high-power airborne ultrasound fields. A spatial characterization of the ultrasound field in the focal region as well as around an artificial head in a simulated application situation was performed. The microphone measurements were supplemented by measuring the radiation force with a balance and were compared to an analytical model of the sound field distribution. The presented results can contribute to the improvement of measurement technology and support a first assessment of the exposure of potential users.

中文翻译：

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高强度聚焦机载超声场的实验表征

高强度聚焦的机载超声领域越来越多地应用于各种技术领域，例如在手势交互过程中产生触觉反馈。需要可靠的声压级测量数据来评估对用户的潜在健康危害。这样的超声场对于定量表征提出了特殊的挑战。高声压级与非线性效应产生的高次谐波相结合，既需要电平线性范围的高上限，又需要测量链的宽带宽。此外，小波长和聚焦导致空间上变化很大的声场。在当前情况下，使用换能器阵列将40 kHz信号聚焦在单个点上。研究了不同类型的麦克风在测量高功率机载超声场方面的适用性。在模拟应用情况下，对焦点区域以及人造头周围的超声场进行了空间表征。通过用天平测量辐射力来补充麦克风的测量值，并将其与声场分布的分析模型进行比较。提出的结果可有助于改进测量技术，并支持对潜在用户的暴露程度进行首次评估。通过用天平测量辐射力来补充麦克风的测量值，并将其与声场分布的分析模型进行比较。提出的结果可有助于改进测量技术，并支持对潜在用户的暴露程度进行首次评估。通过用天平测量辐射力来补充麦克风的测量值，并将其与声场分布的分析模型进行比较。提出的结果可有助于改进测量技术，并支持对潜在用户的暴露程度进行首次评估。