| 摘要 |
In further development of U.S. Pat. No. 6,310,540 B1, an audible signal device comprising of a microprocessor or microcontroller and a sounder element, or a microprocessor or microcontroller in conjunction with electronic circuitry such as discrete components, inductors, or IC's with a sounder element where the resulting sound pressure level is controlled by changing the drive signal's frequency, size, shape, and/or duty cycle.
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