| 摘要 |
PURPOSE:To make excellent the directivity of radiated sound, by fitting a foamed body of silicate and silicic alkali in front of the speaker. CONSTITUTION:When a porous silicate foamed material 1 is filled in the speaker sound outlet and bonded on the disphragm 7, the resonance and split oscillation are suppressed with the foamed filler, and flat frequency characteristics and excellent directivity can be obtained over the broad band. Lighter bulk specific gravity gives better foamed filler, and the directivity of sound is good with greater number in pores and smaller pore diameter. It is suitable the porosity of 85-95% and pore diameter of 3mm. or less, and the strength is insufficient with the porosity of 95% or more and excessive output is required with the porosity of 85% or less. Further, the directivity is bad with the pore diameter of 3mm. or more. Since the foamed body of silicate and silic alkali has no water-resistance, water-proof treatment with vinyl chloride solution, etc. coated is required. |
