The transmission of speech by the usual microphone is almost impossible when the logarithm of the signal-to-noise ratio is negative. In order to obtain intelligible speech in such a case, it is possible to apply a method of speech transmission picking up directly the vibration of the articulatory organs using a vibration transducer which is insensitive to air-coupled noise. In this paper, it is experimentally confirmed that the speech spectrum on the forehead is the most similar to the airborne speech spectrum among the spectra obtained for the vibration of each part of the body. It is found that an articulation score of sixty percent is obtained using a vibration pickup on the forehead even when the signal-to-noise ratio is -35 dB, and furthermore the naturalness of the speech is improved with a compensating filter.