If the microphone connected to the computer, run the program mixer. On different operating systems she has various names and can be run various ways. Look at the sensitivity of the microphone. With it and reduce sensitivity.
If the microphone connected to the recorder, try to find it on a switch method to adjust the recording level (manual or automatic). If you find it possible, select it by manual adjustment of recording level. Then the appropriate regulator will reduce it. To do it by ear will fail, so follow the indications of the indicator (almost all tape recorders, in which manual adjustment of recording level is provided, have it).
Connected in series with the electret computer microphone variable resistor of about 10 kilo Ohm. Increasing the resistance can reduce the voltage of the built-in microphone amplifier circuit FET, thus lowering its sensitivity.
If you use a dynamic microphone (for a computer it is not necessary, but is used in karaoke systems), connect it via an attenuator, is also made of the variable resistor. The value of this resistor should be approximately ten times the resistance of the microphone. Common wire microphone and a cord going to the computer, connect to the left contact of the variable resistor, the output of the microphone to the right, the sound card input as an average.
To reduce the sensitivity of the microphone can be mechanically and wrapping it with several layers of fabric or other material. The number of layers, pick up empirically.
In the case that the device is designed for connection of a dynamic microphone, you can use them together with a microphone, the sensitivity of which is selectively changed depending on whether the source of the sound beside him and affects the membrane on one side more than the other, or is located at a distance affects both sides equally. In the second case the microphone is almost not perceived.