基于简源声波理论的低频气流调制器发声特性研究

A Research on Sound Generation Characteristics for the Low-frequency Airflow Modulators Based on the Simple Sound Source Theory

采用简源声波理论研究低频气流调制器的发声特性。推导了方孔伸缩型、方孔转动型、圆孔转动型3种调制器的排气面积计算公式,采用简源声波理论计算了方孔转动型调制器占空比、气室体积、供气压力和流量这几个工况参数改变时的发声规律,对比了这3种调制器产生的简源声波特性。计算结果表明:方孔伸缩型调制器的失真最小;选择合适的占空比能实现最大声波强度和最小失真;气室体积、供气压力和供气流量越大,发声强度越大,但增加率在减小,失真度先增大后减小。该分析方法能简便快捷地预估低频气流调制器发声性能。

The sound generation characteristics for the low-frequency airflow modulators are studied based on the simple sound source theory in this paper.The calculation formulas for three types of airflow modulators,with flexing square hole,rotating square hole and rotating circular hole are deduced,respectively.The sound generation laws for the rotating square hole modulator due to the changes of the duty cycle,gas chamber volume,gas supply pressure and flow rate are calculated based on the simple sound source theory.The simple sound source characteristics of such three modulators are compared.The calculation results show that the distortion of the flexing square hole modulator is the minimum and the highest sound intensity and the minimum distortion can be realized by choosing proper duty cycle.The bigger the gas chamber volume,gas supply pressure and flow rate are,the higher the sound intensity is.but the incremental ratio is decreased and the distortion is augmented at first and then decreased.The comprehensive consideration of these factors is beneficial to the design and optimization of the airflow modulator.