| 摘要 |
PURPOSE:To display unnecessary reverberation suppressing effect regardless of the thickness and uniformity of an adhesive layer for a piezoelectric oscillator and a back absorber by equalizing the acoustic impedance of the adhesive layer nearly to that of the back absorber. CONSTITUTION:For example, an epoxy adhesive and metallic tungsten or tungsten oxide powder are mixed properly into an adhesive to that the acoustic impedance of the adhesive layer 50 after curing is equal to that of the back absorber 10. The adhesive having the acoustic impedance adjusted as mentioned above is used to adhere the piezoelectric oscillator 20 and sound absorber to each other. The adhesive after adhesion curing forms the adhesive layer 50. Consequently, the influence of the thickness, uniformity, acoustic impedance, etc., of the layer 50 is eliminated to suppress unnecessary reverberation effectively. |
