Buzzer has noise

When the sound which the buzzer generates is not a clear beep sound, we call it noise or broken sound. There are two possible ways to cause the noise.

Improperly used
 If the voltage we input is too high, the diaphragm will easily touch other components, which causes the noise.  When we set the wrong frequency instead of the rated frequency is easy to have noise. For example, if the rated frequency is 2730Hz, but the user input 2400Hz, the noise appears easily, especially within the range 10% ahead of the rated frequency.

Disqualified
 A diaphragm of the buzzer is just set on the braces not firmly attached. Therefore the external force will move the diaphragm and result in the noise.  When we assemble the buzzer, or in the process of user’s production line, if there are some iron chippings invade into the buzzer, the noise will also be caused.