In places of high ambient noise level there are situations where communication by electrical means is precluded. An aid to speech communication in these cases is a mechanical close-talking microphone which can be used in conjunction with ear defenders. This consists, on the outside of the ear cover, of a diaphragm (responding to the pressure gradient of the sound field), which is coupled mechanically to a second diaphragm on the inside of the cover. An acoustic filter system is associated with the air passage through the cover (necessary for the mechanical linkage) so that the attenuation provided by the cover is not impaired. Further improvement in the signal-to-noise ratio has been achieved by making the mechanical system resonant in the range of frequencies that are most important for speech intelligibility. Sentence intelligibility tests on 50 people showed, for example, that when the articulation index was zero for a nearby speech source the median subject obtained a score of 28% using ear covers alone and 84% with the sound transducer; the subjects with extreme scores improved from 0 to 14% and from 88 to 100%, respectively.