Archives of Acoustics

This study explores the localization of virtual sound sources reproduced by a crosstalk cancellation system under different reflective conditions in virtual rooms, analyzing the results with binaural cues. Binaural room impulse responses were generated using the high-order image source method. By modifying the acoustic parameters of the virtual room to manipulate reflection intensity and temporal structure, psychoacoustic experiments were conducted using headphone reproduction. Results show that variations in reflection intensity within a certain range, achieved by altering the room reverberation time (RT), do not significantly affect virtual source localization. However, increasing the loudspeaker–listener distance (altering the temporal structure of reflections) deteriorates localization performance. The main difference between changes in loudspeaker–listener distance and RT lies in whether the reflection’s temporal structure changes. The study highlights the critical role of reflection temporal structure in virtual source localization. Binaural cue analysis shows that even in reverberant environments, interaural time difference (ITD) remains more consistent with localization accuracy than interaural level difference (ILD).

When evaluating speech intelligibility (SI) in automotive cabins, binaural measurements typically employ a fixed dummy head. However, the impact of listener head positions on SI in nonuniform cabin sound fields remains unclear. This study analyzed SI under various listener head positions in an automotive cabin. An artificial mouth was regarded as the speaker, which was placed in three passenger positions. Binaural room impulse responses were measured using a dummy head in the driver’s seat with various head positions. The results show that head position significantly affects SI, with variations of up to 7 dB in octave band magnitudes, more than one just-noticeable difference in the speech transmission index, and shifts of up to 2.5 dB in the speech-reception threshold. SI variability depends on the speaker’s location. Directivity patterns play a crucial role in the front-passenger position, while seat occlusion affects SI at the back-right position, causing substantial decreases below a certain height threshold. At the back-left position, head positions close to the headrest enhance SI due to distance and reflections. Minor head displacements (4 cm apart) generally have insignificant effects on SI, except near seat obstructions or reach critical thresholds.

While acoustic vector sensors (AVS) are well-established for detection and direction-of-arrival (DOA) estimation using co-located pressure and particle motion (PM) measurements, their potential for passive range estimation remains largely unexplored. This paper introduces a novel single-AVS method for passive range estimation to an acoustic monopole source by exploiting the fundamental near-field dominance of PM energy. We derive the frequency and distance dependent ratio (ξ) of kinetic to potential acoustic energy density – a key near-field signature inaccessible to conventional hydrophones. By leveraging simultaneous AVS pressure and PM velocity measurements, our method estimates ξ, inverts the monopole near-field model to obtain the Helmholtz number, and directly computes the range. Crucially, we demonstrate that PM sensors offer a potential signal-to-noise ratio (SNR) advantage over pressure sensors within the near-field (>7.8 dB). Validation under simulated noise conditions shows accurate range estimation (RMSE <10%) for low-frequency sources (<100 Hz) within 8–25 m ranges at 0 dB SNRs, with performance degrading as frequency increases or SNR decreases. Critically, robustness is confirmed using recorded basin noise profiles, overcoming the isotropic Gaussian noise assumption. This technique extends AVS functionality beyond DOA, enabling single-sensor passive ranging without arrays, environmental priors, or reference signals where conventional methods fail.