scholarly journals Directional Loudspeaker Using a Parametric Array

10.14311/862 ◽  
2006 ◽  
Vol 46 (4) ◽  
Author(s):  
A. Ritty
Keyword(s):  
Carrier Frequency ◽  
Nonlinear Acoustics ◽  
Finite Amplitude ◽  
Sound Beam ◽  
Sound Reproduction ◽  
Audible Sound ◽  
Parametric Array ◽  
Film Transducer

The theory for sound reproduction of parametric arrays is based on nonlinear acoustics. Due to the nonlinearity of the air, a finite amplitude ultrasound interacts with itself and generates audible secondary waves in the sound beam. A special feature of this loudspeaker is its sharper directivity compared to conventional loudspeakers of the same aperture size.This paper describes the basis of the theory used for parametric arrays, and presents the influence of the main parameters, e.g., carrier frequency. It also describes some signal pre-processing needed to obtain the desired audible sound. A PVDF (polyvinylidenefluoride) film transducer is also studied in order to produce a prototype to confirm the theory. 

scholarly journals An overview of directivity control methods of the parametric array loudspeaker

2014 ◽  
Vol 3 ◽  
Author(s):  
Chuang Shi ◽  
Yoshinobu Kajikawa ◽  
Woon-Seng Gan
Keyword(s):  
Wide Frequency Range ◽  
Control Methods ◽  
Long Distance ◽  
Sound Beam ◽  
Sound Reproduction ◽  
Reproduction System ◽  
Acoustic Array ◽  
Parametric Array ◽  
Processing Techniques ◽  
Signal Processing Techniques

A sound reproduction system usually consists of several types of loudspeakers to cater to sophisticated applications. The directivity of a loudspeaker is a measure of its efficiency in sending sounds to a particular direction instead of all directions. Demand to control the directivity of a sound reproduction system is gaining momentum with many new designs of directional loudspeakers, including the acoustic dome, horn loudspeaker, loudspeaker array, and parametric array loudspeaker (PAL). The PAL is an application of the parametric acoustic array in air, which generates a sound beam from the interaction of ultrasonic beams. The PAL has several desired features, such as its narrow beamwidth over a wide frequency range, low sound attenuation over a long distance, and ability to reproduce perceptually near sound images. The PAL is also advantageous in using a smaller driving unit to transmit an equally narrow sound beam as compared to the conventional loudspeaker and broadside loudspeaker array. An overview of directivity control methods of the PAL is presented in this paper. In particular, acoustic models and signal processing techniques in controlling the directivity of the PAL are emphasized.

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

2021 ◽  
Vol 263 (5) ◽  
pp. 1676-1682
Author(s):  
Shengqi Tao ◽  
Jing Ren ◽  
Chuang Shi
Keyword(s):  
Frequency Response ◽  
Carrier Frequency ◽  
Ultrasonic Transducer ◽  
Low Frequency ◽  
Consumer Electronics ◽  
Modulation Method ◽  
Sound Beam ◽  
Subjective Testing ◽  
Parametric Array

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.

A more general model equation of nonlinear Rayleigh waves and their quasilinear solutions

2016 ◽  
Vol 30 (08) ◽  
pp. 1650096 ◽  
Author(s):  
Shuzeng Zhang ◽  
Xiongbing Li ◽  
Hyunjo Jeong
Keyword(s):  
Rayleigh Waves ◽  
General Equation ◽  
Wave Motion ◽  
Numerical Solutions ◽  
Second Harmonic ◽  
Approximate Equation ◽  
Finite Amplitude ◽  
Sound Beam ◽  
Quasilinear Theory ◽  
Sound Beams

A more general two-dimensional wave motion equation with consideration of attenuation and nonlinearity is proposed to describe propagating nonlinear Rayleigh waves of finite amplitude. Based on the quasilinear theory, the numerical solutions for the sound beams of fundamental and second harmonic waves are constructed with Green’s function method. Compared with solutions from the parabolic approximate equation, results from the general equation have more accuracy in both the near distance of the propagation direction and the far distance of the transverse direction, as quasiplane waves are used and non-paraxial Green’s functions are obtained. It is more effective to obtain the nonlinear Rayleigh sound beam distributions accurately with the proposed general equation and solutions. Brief consideration is given to the measurement of nonlinear parameter using nonlinear Rayleigh waves.

Reflection of finite‐amplitude waves in a parametric array

1977 ◽  
Vol 62 (2) ◽  
pp. 271-276 ◽  
Author(s):  
T. G. Muir ◽  
L. L. Mellenbruch ◽  
J. C. Lockwood)
Keyword(s):  
Finite Amplitude ◽  
Parametric Array ◽  
Finite Amplitude Waves

QUALITATIVE ANALYSIS OF THE KHOKHLOV–ZABOLOTSKAYA–KUZNETSOV (KZK) EQUATION

2008 ◽  
Vol 18 (05) ◽  
pp. 781-812 ◽  
Author(s):  
ANNA ROZANOVA-PIERRAT
Keyword(s):  
Blow Up ◽  
Viscous Medium ◽  
Finite Amplitude ◽  
Mean Value ◽  
Nonlinear Propagation ◽  
Step Method ◽  
Fractional Step Method ◽  
Sound Beam ◽  
Kzk Equation ◽  
Zero Viscosity

The Khokhlov–Zabolotskaya–Kuznetzov (KZK) equation is considered as a model of nonlinear acoustic which describes the nonlinear propagation of a finite-amplitude focused sound beam which is essentially one-directional, in the thermo-viscous medium.1,7,8 The aim of this paper is the study of the existence, uniqueness, stability, regularity, continuous dependence on the initial value and blow-up of solution of the KZK equation in Sobolev spaces Hs of periodic on x functions and with mean value zero. Existence of shock waves for the model with zero viscosity is proved using S. Alinhac's method.2 Global existence in time of the beam's propagation in viscous media is established for small enough initial data. Existence result is proved by two methods: first by the fractional step method in the particular case ℝ3 and s = 3 to justify the numerical results of Thierry Le Pollès25 and second for the general case ℝn and s > [n/2] + 1 by the approach used in Refs. 12 and 13 for the Kadomtsev–Petviashvili (KP) equation.

Distortion and harmonic generation in the nearfield of a finite amplitude sound beam

1984 ◽  
Vol 75 (3) ◽  
pp. 749-768 ◽  
Author(s):  
Sigurd Ivar Aanonsen ◽  
Tor Barkve ◽  
Jacqueline Naze Tjo/tta ◽  
Sigve Tjo/tta
Keyword(s):  
Harmonic Generation ◽  
Finite Amplitude ◽  
Sound Beam

The transmission of finite amplitude sound beam in multi-layered biological media

2007 ◽  
Vol 362 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Xiaozhou Liu ◽  
Junlun Li ◽  
Chang Yin ◽  
Xiufen Gong ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Finite Amplitude ◽  
Sound Beam ◽  
Biological Media
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