The Research On The Directivity Of Sound Field Of Loudspeaker Array

Parametric loudspeaker array is a new directional sound field equipment. Its beat frequency sound field has a strong directivity so be called the Audio Spotlight. Parametric loudspeaker array is different from traditional speakers that it is composed of ultrasonic transducer. The basic principle depends on modulating ultrasound carrier and audio signal and the self-demodulation in a nonlinear medium. Because of the strong directivity of ultrasonic, the audio signal can be directional dissemination.In 20-20KHz frequency range, we have the same conclusion about the loudspeaker array directivity. But the parametric array loudspeaker technology research has no uniform conclusion. This paper discuss the feasibility and influencing factors of parametric array from the principle and the result of simulation. It provides the theoretical support for the industrial design and production of parametric loudspeaker. The main purpose to make these is that there is little paper to discuss these articles, so I hope to use the most simple graphic to verify the relevant theoretical knowledge.In this paper, firstly through analysis of the principles of traditional speaker systems, it derives the directional formula including the point source, the line source, the line array and matrix array. It discusses frequency, array element and array to the influence of the directivity.Secondly the paper introduces the basic principle of parametric array. With the introduction of the nonlinear acoustics, the paper derive the single parametric loudspeaker directivity formula. Then derive the parametric matrix array directivity formula.Finally, the paper use the Matlab simulate the loudspeaker, and discuss the sound wave frequency, the vibration transducer area, the number of array elements and array size and other factors influencing on the parameters array.