A new asymmetric directional microphone algorithm with automatic mode-switching ability for binaural hearing support devices.

For hearing support devices, it is important to minimize the negative effect of ambient noises for speech recognition but also, at the same time, supply natural ambient sounds to the hearing-impaired person. However, conventional fixed bilateral asymmetric directional microphone (DM) algorithms cannot perform in such a way when the DM-mode device and a dominant noise (DN) source are placed on the same lateral hemisphere. In this study, a new binaural asymmetric DM algorithm that can overcome the defects of conventional algorithms is proposed. The proposed algorithm can estimate the position of a specific DN in the 90°-270° range and switch directional- and omnidirectional-mode devices automatically if the DM-mode device and the DN are placed in opposite lateral hemispheres. Computer simulation and KEMAR mannequin recording tests demonstrated that the performance of the conventional algorithm deteriorated when the DM-mode device and the DN were placed in the opposite hemisphere; in contrast, the performance of the proposed algorithm was consistently maintained regardless of directional variations in the DN. Based on these experimental results, the proposed algorithm may be able to improve speech quality and intelligibility for hearing-impaired persons who have similar degrees of hearing impairment in both ears.

[1]  R K Surr,et al.  Comparison of benefits provided by different hearing aid technologies. , 2000, Journal of the American Academy of Audiology.

[2]  Benjamin W Y Hornsby,et al.  The Effects of Digital Noise Reduction on the Acceptance of Background Noise , 2006, Trends in amplification.

[3]  A. John Van Opstal,et al.  Contribution of Head Shadow and Pinna Cues to Chronic Monaural Sound Localization , 2004 .

[4]  David V. Anderson,et al.  Evaluating the Generalization of the Hearing Aid Speech Quality Index (HASQI) , 2013, IEEE Transactions on Audio, Speech, and Language Processing.

[5]  W. G. Gardner,et al.  HRTF measurements of a KEMAR , 1995 .

[6]  Herman J. M. Steeneken,et al.  Assessment for automatic speech recognition: II. NOISEX-92: A database and an experiment to study the effect of additive noise on speech recognition systems , 1993, Speech Commun..

[7]  Todd A Ricketts,et al.  Effects of Noise Source Configuration on Directional Benefit Using Symmetric and Asymmetric Directional Hearing Aid Fittings , 2007, Ear and hearing.

[8]  Mary T Cord,et al.  Field evaluation of an asymmetric directional microphone fitting. , 2007, Journal of the American Academy of Audiology.

[9]  Mary T Cord,et al.  Ear asymmetries and asymmetric directional microphone hearing aid fittings. , 2011, American journal of audiology.

[10]  W Soede,et al.  Assessment of a directional microphone array for hearing-impaired listeners. , 1993, The Journal of the Acoustical Society of America.

[11]  Albert S. Bregman,et al.  The Auditory Scene. (Book Reviews: Auditory Scene Analysis. The Perceptual Organization of Sound.) , 1990 .

[12]  Ruth A Bentler,et al.  Quantification of directional benefit across different polar response patterns. , 2004, Journal of the American Academy of Audiology.

[13]  W Soede,et al.  Development of a directional hearing instrument based on array technology. , 1993, The Journal of the Acoustical Society of America.

[14]  Andries P. Hekstra,et al.  Perceptual evaluation of speech quality (PESQ)-a new method for speech quality assessment of telephone networks and codecs , 2001, 2001 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.01CH37221).

[15]  James M. Kates,et al.  The Hearing-Aid Speech Quality Index (HASQI) , 2010 .

[16]  Mark E Lutman,et al.  Speech Recognition and Comfort Using Hearing Instruments with Adaptive Directional Characteristics in Asymmetric Listening Conditions , 2005, Ear and hearing.