| 摘要 |
PURPOSE:To measure sound field automatically under a suitable sound volume by controlling a variable attenuator with a speaker to which an output signal is supplied from a variable attenuator and a microphone collecting the loudspeaking sound from the speaker so as to make the measured sound volume coincident to the cuitable sound volume. CONSTITUTION:The sound field is measured by placing right/left speakers 9L, 9 9R as shown in Fig. and the microphone 10 at a desired position in a listening room LRM. A noise signal from a noise oscillator 4 is fed to one of the speakers 9L, 9R through a route of variable attenuator 6 - line-out amplifier 7 -output amplifier 8, a noise is outputted in the listening room LRM, and the attenuation of the variable attenuator 6 is decreased from the maximum attenuation by, e.g., 1dB each. The sound volume is measured by a sound volume measuring means 23 and a microprocessor 18. The sound volume of the sound collection signal is increased gradually attended with the reduction in the attenuation of the variable attenuator 6 and when the measured sound volume reaches a suitable level, the attenuation of the variable attenuator 6 is fixed to the attenuation at that point and the sound field is measured by controlling a sound field measuring means 24. |
