Aiming at scientific understanding of color association after listening to vowel sounds, cross-modal association characteristics was investigated using parameters directly extracted from speech and color. A perceptual experiment was conducted by employing five Japanese vowel sounds produced by multiple male and female native speakers differing in spectral characteristics. For color description, three attributes (hue, saturation and value) of 153 color tips of Practical Color Coordinate System (PCCS) selected after listening to vowel speech were employed. To enable scientific interpretation, acoustic features of vowel sounds (F0, pitch range, intensity, F1, F2, F3, F4) were used. Regression analyses were carried out between these speech and color parameters. From the results using multiple linear regression and neural networks, significant correlations could have observed between F1, pitch range & F2 and hue, F0 & F2 and value of color. These experimental findings can exactly and clearly show vowel-color association characteristics which have been partially studied in phonetics and cognitive science fields mainly using speech and color categories. These precise parametric correlations between color and speech can provide scientific knowledge for further investigations of cross-modal correlations in multiple research fields which will give the new possibilities for multi-modal information expression.

Statistical, geometrical, or wave-based acoustics are used as the basis for sound field analysis of buildings. As each technique has its own merits and limitations, it is imperative to select a suitable method for the target space and frequency. However, different techniques can be combined to obtain a precise wideband solution. Herein a hybrid technique, which combines the calculated results using the back-tracing method and the finite-difference time-domain (FDTD) method, is proposed to realize a wideband impulse response. Additionally, the required filters and corrections to properly combine the results are discussed. Then the effectiveness of the hybrid technique is evaluated from the viewpoints of required memory and computational time. Compared to the back-tracing method alone, the hybrid technique significantly improves the time and frequency response results, especially at low frequencies. Finally, the appropriate crossover frequency for hybrid analysis is discussed.

The interaural time difference (ITD) plays an important role in spatial hearing, particularly in azimuthal localization of sound images. Although the ITD is essentially determined by the geodesic distance between two ears, researchers have reported that the ITD is greater for lower frequencies. However, the origin of this frequency-dependence has not been revealed. This study investigates how the ITD is physically characterized to have a frequency-dependent nature by conducting measurements and numerical simulations. Dummy head measurements show that the ITD varies with frequency because the apparent propagation time to the ipsilateral ear decreases for low frequency. Dummy head simulations confirmed this phenomenon and revealed that the apparent propagation time decreases because of a sound pressure phase shift due to reflections from the head. Circular plate simulations revealed that the circular profile including its lateral surface and edge produces reflections that are relevant to the phase shift, yielding the frequency-dependence of the apparent propagation time. Furthermore, rigid sphere simulations showed that such reflections are produced even by smooth convex surfaces without clear-cut edges. These results strongly suggest that a major factor in the production of the frequency-dependence of ITDs is backscatter diffractions from convex surfaces of the head and the pinna.

Many have spun a coin or other disk on a table, observing — and listening! — that — while its motion comes to rest, the angular velocity of the contact point and the frequency of the emitted sound raise in a striking way. This dynamical system is known as the "Euler disk," and its physics is theoretically understood as a "finite time singularity" in form of an inverse power law. Various dissipation mechanisms lead to different exponents in the power law. The present investigation is about different configurations of the Euler disk using acoustical and mechanical data. We present results for the well-known Euler disk toy, well in accord with a model of viscous air dissipation. This is the first measurement using the acoustical signal for the dynamics of the Euler disk. Moreover, we present new cases where other dissipation mechanism must be dominant. Experiments are carried out with simple means and using a smartphone for recording and analysing data. This and interesting physics of the Euler disc make it a good candidate e.g. for undergraduate lab-work courses or research projects, which can spark students interest in acoustics, and more generally in applying physics to phenomena of everyday life.