Planar projection methods have been shown to rapidly relate fields between two planes. Such an approach is particularly useful for characterizing transducers, since only a single plane needs to be measured in order to characterize an entire field. The present work considers the same approach in the presence of an arbitrary dispersion relation. Unlike traditional methods that use Fourier solutions of the time-domain wave equation, the approach starts from a frequency-domain Helmholtz equation for waves in a dispersive medium. It is shown that a transfer function similar to that derived from time domain equations can be utilized. Both the forward- and backward-projection behaviors are examined and it is demonstrated that the approach is invariant to propagation direction.
To examine how the perceptibility of environmental sounds is affected by listening to music through earphones, the hearing thresholds for pure tones presented through a loudspeaker were measured. Under the condition that the listener wore canalphones, thresholds were considerably higher than those under the condition that the listener’s ears were open. When pseudo-music signals were presented through the canalphones at the A-weighted sound pressure level of 70 dB, the hearing threshold at 2 kHz was almost 70 dB higher than the absolute threshold. How environmental noise affects the listener’s comfortable level of music played on portable audio devices was also examined. The mean comfortable listening levels (A-weighted) under a quiet condition were between 65 dB and 69 dB and those under a noisy condition ranged between 73 dB and 76 dB. It was indicated that when listening to music through canalphones at a comfortable level on a busy street, many environmental sounds would be inaudible.
In this study, we conducted a comparative experiment on emotion perception among different cultures. Emotional components were perceived by subjects from Japan, the United States and China, all of whom had no experience living abroad. An emotional speech database without linguistic information was used in this study and evaluated using three- and/or six-emotional dimensions. Principal component analysis (PCA) indicates that the common factors could explain about 60% variance of the data among the three cultures by using a three-emotion description and about 50% variance between Japanese and Chinese cultures by using a six-emotion description. The effects of the emotion categories on perception results were investigated. The emotions of anger, joy and sadness (group 1) have consistent structures in PCA-based spaces when switching from three-emotion categories to six-emotion categories. Disgust, surprise, and fear (group 2) appeared as paired counterparts of anger, joy and sadness, respectively. When investigating the subspaces constructed by these two groups, the similarity between the two emotion groups was found to be fairly high in the two-dimensional space. The similarity becomes lower in 3- or higher dimensional spaces, but not significantly different. The results from this study suggest that a wide range of human emotions might fall into a small subspace of basic emotions.
This Technical Report describes air conduction hearing thresholds measured for pure tones at conventional audiometric frequencies and extended high frequencies using apparatus and procedure in accordance with relevant ISO and IEC standards. The subjects were otologically normal Japanese high-school students aged 15–17 years. Descriptive statistics of their threshold levels are presented in graphical and tabular forms. Analyses of the measured data showed that the median threshold levels did not significantly deviate from the reference level of 0 dB and that they differed depending on the earphones used: supra-aural or circumaural earphones. These measurement results might be used effectively for revision of ISO 7029:2000, which describes the method for calculating the estimated hearing sensitivity decline as a function of age.