| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent a large sound volume from being outputted when powered on. SOLUTION: When the power source is turned on, a set sound volume level Rs of a volume is detected (S1), and it is discriminated whether the current set sound volume level Rs is higher than a stored sound volume level Rm read out from a storage part or not (S2 and S3); and if the current set sound volume level Rs is higher than the stored sound volume level Rm, this state is reported by an indication on a display part and a message output from a headphone (S4), and the output sound volume is locked to the stored sound volume level Rm by a control part (S5). The volume is operated by later interrupt handling (S7), and the output sound volume is unlocked when the current set sound volume level Rs is reduced to the stored sound volume level Rm. |
