Effect of the ultrasonic emitter on the distortion performance of the parametric array loudspeaker

Shi, Chuang; Kajikawa, Yoshinobu

doi:10.1016/j.apacoust.2016.05.013

Cited by 7 publications

(3 citation statements)

References 26 publications

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“…Furthermore, the dual frequency PA needs to be produced as a special sound source to ensure that two high-frequency signals of strong output are collimated, while the broadband PA has the advantage of being a high-frequency sound source that can output a strong signal. Recently, studies have been conducted on a modulation technique of primary signal of broadband PA [ 29 , 30 , 31 ].…”

Section: Fundamental Principle Of the Parametric Arraymentioning

confidence: 99%

Comparative Experimental Investigation on Optimal Parametric Array Types

Jung

Song

Kim

et al. 2021

Sensors

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As a sound transmitting device that relies on the nonlinearity of a medium, a parametric array (PA) can generate high-directivity low-frequency signals using a small aperture transducer and high-frequency signals. Despite their relatively low source level, the PA is frequently used to measure the acoustic properties of materials in low-frequency regions owing to their high directivity in confined acoustic water tanks. Therefore, methods for improving the source level of secondary signals are of interest. Currently, there are two driving methods for PA: the dual-frequency PA and the broadband PA with amplitude modulation. In this study, we share the results of an elaborate and comparative experimental investigation of these two driving methods. Comparisons are made and discussed in terms of the intensity of the generated secondary signal and its characteristics in the frequency domain. Based on these factors, we confirmed that the broadband PA was more suitable as the sound source of the low-frequency characteristic measurement system of acoustic materials.

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Section: Fundamental Principle Of the Parametric Arraymentioning

confidence: 99%

Comparative Experimental Investigation on Optimal Parametric Array Types

Jung

Song

Kim

et al. 2021

Sensors

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“…Generally, the frequency response of the ultrasonic emitter is analogous to a triangle [15]. Conventionally, the PAL sets the carrier frequency at the vertex of the triangle to maximize the out power of the carrier wave, i.e.…”

Section: Carrier Frequency Optimizationmentioning

confidence: 99%

Virtual bass preprocessing and carrier frequency optimization for the parametric array loudspeaker

Tao¹,

Ren²,

Shi³

2021

inter noise

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The parametric array loudspeaker (PAL) is a novel type of loudspeaker that can project a directional sound beam. It is usually used in creating personal sound zone and projecting private messages to a targeted audience. However, the PAL has a very poor low-frequency response due to the inherent nonlinear acoustic principle generating sound from ultrasound in air. A psychoacoustic signal processing method known as the virtual bass (VB) has been proved to be an effective method to improve the bass quality of consumer electronics with miniature or flat loudspeaker unit. This paper proposes the VB processing based on the phase vocoder (PV) for the bass enhancement of the PAL that adopts a vestigial sideband modulation method. The harmonics generated by the VB processing are presented in the partial sideband, while the audio input without the bass component is embedded in the full sideband. A measure, namely the in-band peak flatness, is thereafter proposed in this paper to determine the optimal carrier frequency, given a practical uneven frequency response of the ultrasonic transducer. The subjective testing results validate that the proposed VB processing together with the optimal carrier frequency can finally realize the improvement of bass sound quality of the PAL.

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“…The square root is an inverse operator to the square function in the Berktay's far-field solution. Moreover, equalization of the ultrasonic emitter before the square root method is expected to improve the performance in practice [8]. A post equalization is usually carried out by the double integral to offset the high-pass filter in the Berktay's far-field solution [9].…”

Section: Introductionmentioning

confidence: 99%

Extended convolution model for computing the far-field directivity of an amplitude-modulated parametric loudspeaker

Shi¹,

Wang²,

Han³

et al. 2022

J. Phys. D: Appl. Phys.

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The convolution model of the parametric loudspeaker describes the far-field directivity of the difference-frequency wave by the product directivity of two ultrasonic primary frequencies convolved with Westervelt's directivity. This can be extended to the case when the primary wave is amplitude-modulated thus resulting in the harmonic distortion of the self-demodulated wave. This paper proposes the extended convolution model with Westervelt's directivity and Berktay's directivity respectively. The angle-dependent harmonic distortion of the parametric loudspeaker is thereafter investigated, which is a topic not often mentioned in previous literature but is of significance in practice. The measurement, numerical simulation and model results are compared for the case when the double sideband (DSB) modulation is adopted and the frequency response of the ultrasonic emitter is a known factor. The comparison validates that the extended convolution model provides accurate predictions that are consistent with the measurement results and the extended convolution model is a simpler way to compute the far-field directivity of an amplitude-modulated parametric loudspeaker as compared to the numerical simulation.

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Effect of the ultrasonic emitter on the distortion performance of the parametric array loudspeaker

Cited by 7 publications

References 26 publications

Comparative Experimental Investigation on Optimal Parametric Array Types

Comparative Experimental Investigation on Optimal Parametric Array Types

Virtual bass preprocessing and carrier frequency optimization for the parametric array loudspeaker

Extended convolution model for computing the far-field directivity of an amplitude-modulated parametric loudspeaker

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