Complete tropism microphone: Magnetic, pottery and porcelain and be stationed in extremely microphone of form of characters or letters is complete tropism microphone, wait for a quantity to accept the sound of each direction namely. Current, halt extremely microphone of form of characters or letters is applied extensively at acoustics domain, it is to use the permanent polarization material of a kind of insulation to be made. Sound enters microphone, the density change of sound wave causes the vibration of thin metal diaphragm that carries negaive electricity, immediately is sound energy change mechanical energy, diaphragm vibration is in be stationed in pressure of the generation on airframe, deliver to halt extremely body backboard. Halt body backboard and diaphragm bottom are linked together with preamplifier of field effect transistor and extremely one terminal notifies outward department. When diaphragm is oscillatory, diaphragm and halt extremely the distance between body backboard and space produce a change, generation voltage, through securing the field effect transistor on microphone, mechanical energy change is electric energy, repass terminal passes amplifier. Be stationed in extremely microphone of form of characters or letters frequency noise is wide, sensitivity is tall and durable, and diaphragm is the part that it moves exclusively.
Directivity microphone: Will classify according to polarity form, right in front the sound response that transmits at the back of the acoustical signal to noise ratio that transmits is sensitive much. Directivity microphone has two mouth two end in diaphragm, at the same time. The oscillatory basis of diaphragm is phasic relation, depend on the pressure of two end is poor. After one close acoustics mesh has the front place of acoustical aperture delay time action, the sound that transmits from the back so but at the same time aperture of two sound after once upon a time arrives brace up film is quits, consequently the polarity graph of directivity microphone submits heart form.
