Multisensor speech input for enhanced immunity to acoustic background noise

The aim of this work is to develop multisensor configurations of sensors for transducing speech in order to achieve enhanced immunity to acoustic background noise. We performed detailed measurements of the sound field in the vicinity of the mouth and neck during speech using pressure and pressure gradient microphones and an accelerometer. We investigated the properties of the measured signals from the various sensor types and positions through long-term and short-term spectral analyses and from articulation index scores computed assuming ambient noise typical of that in a fighter aircraft cockpit. From the results of this investigation, we developed a two-sensor configuration involving an accelerometer and a gradient microphone. Results from formal speech intelligibility and quality tests in simulated fighter aircraft cockpit noise show clearly that each of the two-sensor signals under test outperforms the signal from the gradient microphone alone and that the performance improvement generally increases with the noise level.