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.     

The optimal therapy of calcineurin inhibitors for pregnancy in kidney transplantation

We investigated the effects of pregnancy and delivery on renal function in transplant recipients and the relationship between doses of immunosuppressants and blood drug levels during pregnancy in 75 women with 88 deliveries. Significant serum creatinine elevation (> 0.5 mg/dL) was found in eight deliveries. In the remaining 80 cases, serum creatinine was reduced by an average of 0.14 mg/dL and returned to pre‐pregnant levels after delivery. Tacrolimus was used in 28 deliveries and cyclosporine in others. Tacrolimus blood trough level declined from 5.8 ± 2.8 ng/mL 12 months before delivery to 4.2 ± 1.8 ng/mL at second trimester; therefore, drug dose was increased from 4.1 ± 1.9 mg/d at first trimester to 5.5 ± 2.5 mg/d at delivery. Similarly, cyclosporine levels were 125.1 ± 65.1 ng/mL 12 months before delivery and 75.4 ± 35.0 ng/mL at second trimester resulting in dose elevation from 183.0 ± 71.8 mg/d at first trimester to 225.4 ± 85.1 mg/d at delivery. Renal function in female kidney transplant recipients improved slightly during pregnancy and returned to pre‐pregnant level after delivery. The dose elevation of calcineurin inhibitor by approximately 20–25% should be considered during gestational period to maintain optimal blood drug level.