| 摘要 |
PURPOSE:To obtain a natural preferable hearing sensation state with simple constitution and operation by varying the frequency characteristics of a power amplifier with a switch associated with a changeover switch for switching between connection terminals of an internal and an external speaker. CONSTITUTION:The switch S2 associated with the switch S1 which switches the output to the external speaker and external speaker selectively is provided, and the power amplifier 17 has the frequency characteristics varied with the switch S2. This switch S2 changes connections of capacitors of the feedback circuit of the amplifier 17 and operates associatively with the switch S1. When the switch S1 is placed at a side A, the switch S2 is also at a side C and connected to a capacitor C1 to drive the internal speaker. When the switch S1 is at a side B, on the other hand, the switch S2 is at a side D and a capacitor C is connected to drive the external speaker.
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