The ATM41a is a cardioid dynamic vocal microphone.
Features
Field-proven performance for close-up vocals
Low-mass diaphragm and high-efficiency magnetic circuit
Tailored response provides natural, full-range reproduction
Excellent off-axis rejection for minimum feedback
Superior internal shock mounting
What a Microphone Does
Like phono cartridges, headphones, and loudspeakers, the microphone is a transducerÖin other words, an energy converter. It senses acoustic energy (sound) and translates it into equivalent electrical energy. Amplified and sent to a loudspeaker or headphone, the sound picked up by the microphone transducer should emerge from the speaker transducer with no significant changes.
About Dynamic Microphones
Comparison of microphone types to loudspeakers may help you more readily understand their operation. Dynamic microphones can be considered as similar to conventional loudspeakers in most respects. Both have a diaphragm (or cone) with a voice coil (a long coil of wire) attached near the apex. Both have a magnetic system with the coil in its gap. The difference is in how they are used. With a speaker, current from the amplifier flows through the coil. The magnetic field created by current flowing through the voice coil interacts with the magnetic field of the speaker's magnet, forcing the coil and its attached cone to move back and forth, producing sound output.
A dynamic microphone operates like a speaker "in reverse." Changing sound pressure moves the diaphragm. This moves the coil, which causes current to flow as lines of flux from the magnet are cut. So, instead of putting electrical energy into the coil (as in a speaker) you get energy out of it. In fact, many intercom systems use small speakers with lightweight cones as both speaker and microphone, by simply switching the same transducer from one end of the amplifier to the other. A speaker doesn't make a great microphone, but it's good enough for that application.
Dynamic microphones are renowned for their ruggedness and reliability. They need no batteries or external power supplies. They are capable of smooth, extended response, or are available with "tailored" response for special applications. Output level is high enough to work directly into most microphone inputs with an excellent signal-to-noise ratio. They need little or no regular maintenance, and with reasonable care will maintain their performance for many years.
A Word about Audio-Technica
Audio-Technica has been dedicated to advancing the art and technology of electro-acoustic design and manufacturing since 1962. From a beginning in state-of-the-art phono cartridges, A-T has expanded over the years into high-performance headphones, microphones, mixers, and electronic products for home and professional use. In each new area the goal has been to create innovative, problem-solving products. The results of these engineering and production efforts can be seen in the effective use of A-T products in a broad spectrum of applications.
Audio-Technica microphones, for example, are found in daily use in major broadcast and recording studios, and relied upon by top touring musicians. A-T mics are chosen for important installations and major events, such as the US House of Representatives, the US Senate, the Super Bowl, World Cup Soccer, and the Olympics. Whether in the home, or in schools and universities, boardrooms, council chambers, or places of worship, Audio-Technica products are providing superior performance and exceptional value worldwide.
Technical Info
Element: Dynamic
Impedance: 250 ohms
Polar Pattern: Cardioid
Weight: 11.6 oz (328 g)
Frequency Response: 50 - 16,000 Hz
Output Connector: XLRM-type
Open Circuit Sensitivity: -56 dB (1.5 mV) re 1V at 1 Pa
Accessories Furnished: AT8406 stand clamp; protective pouch
Because this item is used at your mouth or ear, it cannot be returned once opened due to health reasons. 
