Improvements in Speech Intelligibility using Innovative Noise Reduction Techniques

Advanced noise reduction techniques are required to improve intelligibility and reduce noise in ANR headsets employed by U.S. Army personnel. Intercommunication headsets currently employed by tank crewmen expose wearers to unacceptably high levels of background noise when the communication system microphone is keyed and a person is talking. This noise induces fatigue in the wearers, decreases job performance and efficiency, increases perceived operational workload, and could lead to permanent hearing loss. This noise also masks incoming speech and other non-verbal audio signals essential to mission success and crew safety. Our proposed research introduces new technology that will significantly reduce noise and improve intelligibility using a combination of modular hardware components and advanced noise reduction signal processing techniques. These include: 1) an adaptive beamforming multi-microphone array that will increase the speech SNR and reduce noise entering the headset through the voice input, 2) an optimized ANR earphone, which will increase the ANR attenuation bandwidth to include higher portions of the speech range, 3) improved passive earcups and seals made from low-frequency passive sound absorbing materials, which will decrease low-frequency noise entering the system through the earcups and seals, and 4) improved speech filtering using wavelet transforms, spectral subtraction, or others, which will improve speech signal extraction from noise. The overall benefit to the U.S. Army from this combined approach will be modular hardware and software components that can be readily integrated into a variety of headset applications to reduce noise-induced fatigue, reduce hearing loss, improve operational performance, increase comfort and above all, improve the safety of U.S. Army personnel. These benefits aptly apply to other headset wearers as well. BENEFITS: These technologies can be applied to improve intelligibility and reduce noise in commercial and military aviation headsets, commercial and military industrial hearing protection devices, and commercial personal hearing reduction headsets (i.e., for use on board a plane, in other noisy vehicles, or around noisy yard equipment, etc.). They