The beyerdynamic MM1 is a measurement microphone which has been designed specifically for measuring sound reinforcement and PA-systems. It is designed to work with spectrum analyzers for measuring frequency response and sound pressure levels of loud speaker systems. The MM 1 is the ideal microphone for the measurement of audio signals in the research, development, for reverberation testings and other applications. The narrow tubular construction ensures that the microphone has negligible influence on the sound field so that an increase in sound pressure is avoided with high frequencies. A natural reproduction is achieved due to the linear frequency response.