The Endevco microphone model EM40AO is a ½-inch precision reference microphone for laboratory use, e.g. in couplers, ear simulators, enclosures and at boundaries. It is a prepolarized pressure microphone with a large dynamic range and an extended frequency response. As a pressure microphone, the model EM40AO measures the sound pressure at the location of its diaphragm. It has a flat pressure-frequency response over its entire working frequency range (see Fig.1). In an open sound field, a pressure microphone will also include the disturbing effects of its presence in the sound field. These are minimal at low frequencies (wavelengths >> microphone size). At higher frequencies the effects of reflections and diffractions must be accounted for. Generally, they lead to an increase in the measured sound pressure and corrections have to be made. Fig.2 shows what these corrections are in a free field for various angles of incidence. Endevco Isotron® preamplifiers are also available for use with the model EM40AO, these are: ½-inch preamplifier model EM26CA ¼-inch preamplifier model EM26CB with the included adaptor All Endevco microphones comply with the specifications of IEC 1094: Measurement Microphones, Part 4: Specifications for working standard microphones. Non-corrosive, stainless materials are used in manufacturing these microphones to enable them to withstand rough handling and corrosive environments. All Endevco microphones are guaranteed for 5 years and are individually checked and calibrated before leaving the factory. An individual calibration chart is supplied with each microphone. Typical applications • Precision sound pressure measurements • Very high frequency measurements • Laboratory reference measurements • In couplers and ear simulators • Use with Endevco Isotron® preamplifiers Endevco® model EM40AO ½” Wide-frequency pressure microphone Description cmyk

Endevco® model EM40AO ½” Wide-frequency pressure microphone APPLIES TO CALIFORNIA FACILITY Continued product improvement necessitates that Endevco reserve the right to modify these specifications without notice. Endevco maintains a program of constant surveillance over all products to ensure a high level of reliability. This program includes attention to reliability factors during product design, the support of stringent Quality Control requirements, and compulsory corrective action procedures. These measures, together with conservative specifications have made the name Endevco synonymous with...