The Use of Airborne Ultrasonics for Generating Audible Sound Beams

JAES 01/1999; 47:726-731.
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    • "Conventional loudspeakers emit sound in a nondirectional way (Gan et al. 2012). However, ultrasonic parametric arrays transmit a highly directional sound beam much like a spotlight (Yoneyama et al. 1983, Pompei 1999, Gan et al. 2012). The beam starts out as a mixture of 2 ultrasonic frequencies. "
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    ABSTRACT: Pest avian wildlife is responsible for substantial economic damage every year in the United States. Previous technologies used to deter starlings have generally failed because birds quickly habituate to startle regimes. In this study, conducted from May to July 2013, we focused on altering the foraging behavior of the European starling (Sturnus vulgaris), a pest bird that is responsible for crop losses and also poses notable risk for bird–aircraft strikes. The goal of our project was to develop an effective system to limit starlings' use of a food patch. Using nonlinear ultrasonic parametric arrays, we broadcast a directional sound that overlapped in frequency with starling vocalizations and was contained in a specific area, creating a “net.” We hypothesized that the “sonic net” would disturb acoustic communication for starlings, causing them to leave and feed elsewhere. Using wild-caught starlings in a large aviary, we deployed the sonic net over one food patch while leaving another food patch unaltered, and assessed their presence and feeding for three consecutive days. The sonic treatment decreased starlings' presence at the treated food patch, on average by 46%. Additionally, we assessed whether the sonic net disrupted the birds' response to an alarm call. When under the sonic net, starlings did not respond to the alarm call, suggesting that the sonic net disrupted acoustic communication. The sonic net is a promising new method of decreasing foraging activity by pest bird species. © 2015 The Wildlife Society.
    Wildlife Society Bulletin 04/2015; DOI:10.1002/wsb.529 · 1.27 Impact Factor
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    • "They have attracted intensive interest since almost half century ago [1]. A great deal of achievements have been made in theory and practice [2]–[6]. Yoneyama et al. [7] first modulated ultrasonic signals with audio signals using double sided band amplitude modulation (DSBAM) and fed to parametric loudspeakers to produce audio sounds through the demodulation process provided by the nonlinearity of the air, which however, also generates harmonic distortion degrading the sound quality of the desired sounds. "
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    ABSTRACT: Recently, the general Volterra filter (VF) has been adopted for the modeling of parametric loudspeakers. However, the computation complexity of the VF is too high for real-time implementation. In this paper, a one-dimension Volterra filter (ODVF) with much lower complexity is introduced to model and compensate for the nonlinearity of parametric loudspeakers. A theoretical framework for ODVF model identification is established and a method of measuring the ODVF kernels using the exponential swept-sine signal is provided. The validity of modeling the nonlinearity of the parametric loudspeaker using the ODVF is verified theoretically and experimentally. Based on the established ODVF model, an inverse filter is designed to compensate for the 2nd harmonic distortion of the parametric loudspeakers. To further reduce the 3rd harmonic distortion, an improved compensation method is also proposed. Experimental results show that the performance of the ODVF-based compensation is comparable to that of the Volterra-filter based compensation.
    12/2014; 22(12):2169-2181. DOI:10.1109/TASLP.2014.2363414
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    • "Therefore, the single sideband amplitude modulation (SSBAM) was proposed to result in the same envelope function as the SRAM but with a relaxed bandwidth requirement [5]. Meanwhile, a double integral operator was introduced into the SRAM as an equalizer to further reduce harmonic distortions [6]. However, till now, the most widely applied preprocessing method is still the DSBAM [7]. "
    The 1st Joint Symposium on Signal Processing and Control Systems in CYCU and KU, Jungli, Taiwan; 06/2014
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