| 摘要 |
A telephone, for example a cellular radio telephone, is provided with means for generating a ringing tone upon detection of an incoming call, the volume of the ringing tone being controlled depending on the level of ambient noise to ensure that the ringing tone volume is sufficient to be heard above the ambient noise while not being too loud to startle. This is achieved by using the telephone's microphone (1) to detect the ambient noise level, comparing this with reference values stored in the memory of the telephone's microprocessor (6) and providing a control signal to the telephone's loudspeaker (8) to produce a ringing tone of a suitable volume. <IMAGE>
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