The present study has two purposes. One is to examine a simulation method for localizing a sound image. The authors propose a parametric HRTF model to simulate vertical sound localization. The parametric HRTF is recomposed only of the spectral peaks and notches extracted from the measured HRTF, and the spectral peaks and notches are expressed parametrically with center frequency, level, and sharpness. The other purpose is to clarify the contribution of each spectral peak and notch as a spectral cue. Localization tests were carried out in the upper median plane using the subjects’ own measured HRTFs and the parametric HRTFs with various combinations of spectral peaks and notches. The results show that the parametric HRTF recomposed using the first and second notches (N1 and N2) and the first peak (P1) provides almost the same localization accuracy as the measured HRTFs. Observations of the spectral peaks and notches indicate that N1 and N2 change remarkably as the source elevation changes, whereas P1 does not depend on the source elevation. In conclusion, N1 and N2 can be regarded as spectral cues, and the hearing system could utilize P1 as the reference information to analyze N1 and N2 in ear-input signals.

Dependence of superconducting transition temperature on the thickness of Nb films deposited upon several kinds of substrates by means of rf sputtering was studied in search of rudimental data necessary in fabricating variable thickness microbridge type Josephson junctions. The transition temperature was found to lower with the decrease of Nb film thickness. The lowering characteristics of the transition temperature were found to vary in accordance with whether the substrate surface was amorphous or crystalline. The cause of the variance was studied on thin films with the aid of x-ray diffraction pattern analysis and measurement of film resistance.

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A general polymer, poly­(methyl methacrylate) (PMMA) is utilized as a unique templating agent for forming crack-free mesoporous TiO2 films by a sol–gel method. The pore morphologies were found to be controllable by varying the amount of PMMA. The PMMA-mediated mesoporous TiO2 layer has been applied for the first time to perovskite solar cells exhibiting a best power conversion efficiency of ≥14%, which is ca. three times higher than that using a TiO2 layer prepared by the same sol–gel method without the polymer addition (5.28%). Remarkably, it was superior to the reference device with mesoporous TiO2 layer prepared with conventional nanoparticle paste (13.1%). Such mesostructure-tuned TiO2 layers made by the facile sol–gel technique with a commercially available polymer additive has the great potential to contribute significantly toward the development of low-cost, highly efficient perovskite solar cells as well as other functional hybrid devices.

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