Features Of Sound Fields Research Articles

Range estimation in a weakly range-dependent waveguide in the South China Sea using single hydrophone and multi-task trained deep neural network

In this paper, an underwater source range estimation method using a multi-task trained deep neural network is proposed. Unlike existing machine learning frameworks, in this case, the physical quantities utilized for the training and testing are not identical. The training data parameter is the phase of the complex sound pressure, which is independent of the source and receiver depth and can be generated easily by an acoustic propagation model with only a few environmental parameters, decreasing computational costs significantly. The testing data parameter is the realistically-measured complex sound pressure. Instead of simply using the range as the only supervision signal, two other parameters — the phase mode and the bottom sound speed — are applied as auxiliary labels during the training process, embedding additional information about the sound field into the deep model. The projection between the sound field features and the range extracted from the training data by the deep model is applied to range estimation task on testing data. The effectiveness of the proposed approach is verified for a weakly range-dependent waveguide in the South China Sea by localizing several upsweep signals within a frequency band of 20–200 Hz. Testing results illustrate that the proposed method outperforms the classical matched impulse response approach and deep-learning-based single-label trained models, with the mean absolute percentage error (MAPE) decreasing by 24.63% and 59.46%, respectively. The mechanism of promotion is explained by comparing visualized hidden features of the neural network using t-distributed stochastic neighbor embedding (t-SNE) between the single-task and multi-task approach, showing that the latter helps to construct a more reasonable data manifold in high-dimensional space and thus ensures better performance of the deep model. We also fine-tune the network with a few realistic samples and further improve the performance by up to 25.34% against the baseline.

Towards predicting immersion in surround sound music reproduction from sound field features

When evaluating surround sound loudspeaker reproduction, perceptual effects are commonly analyzed in relationship to different loudspeaker configurations. The presented work contributes to this by modeling perceptual effects based on acoustic properties of various reproduction formats. A model of immersion in music listening is derived from the results of an experimental study analyzing the psychological construct of immersive music experience. The proposed approach is evaluated with respect to the relationship between immersion ratings and sound field features obtained from re-recordings of the stimuli using a spherical microphone array at the listening position. Spatial sound field parameters such as inter-aural cross-correlation (IACC), diffuseness and directivity are found to be of particular relevance. Further, immersion is observed to reach a point of saturation with greater numbers of loudspeakers, which is confirmed to be predictable from the physical properties of the sound field. Although effects related to participants and musical pieces outweigh the impact of sound field features, the proposed approach is found to be suitable for predicting population-average ratings, i.e. immersion experienced by an average listener for unknown content. The proposed method could complement existing research on multichannel loudspeaker reproduction by establishing a more generalizable framework independent of particular speaker setups.

Directional sound field decay analysis in performance spaces

The analysis of the spatio-temporal features of sound fields is of great interest in the field of room acoustics, as they inevitably contribute to a listeners impression of the room. The perceived spaciousness is linked to lateral sound incidence during the early and late part of the impulse response which largely depends on the geometry of the room. In complex geometries, particularly in rooms with reverberation reservoirs or coupled spaces, the reverberation process might show distinct spatio-temporal characteristics. In the present study, we apply the analysis of directional energy decay curves based on the decomposition of the sound field into a plane wave basis, previously proposed for reverberation room characterization, to general purpose performance spaces. A simulation study of a concert hall and two churches is presented uncovering anisotropic sound field decays in two cases and highlighting implications for the resulting temporal evolution of the sound field diffuseness.

TARGET SEARCH AND NAVIGATION BY SPATIAL HEARING USING INTER-AURAL SIGNALS

In this paper, the feasibility of utilizing spatial hearing for robot's pose search is investigated, and a novel and robust robot location and orientation detection method for highly complex and noisy environment is proposed. Unlike traditional methods, the proposed method imitates the behavior of human or animals that utilize the experience of sound field features at different location and orientation in a normal environment to locate themselves. Since this method can provide global location and orientation detection, it is suitable to navigate the robot from the present location to the destination by adjusting its orientation.

Intensity and space-time characteristics of the sound field in the underwater sound channel of the Black Sea

Experimental data are presented on the intensity and space-time characteristics of the sound field generated by explosions in underwater and surface sound channels of the Black Sea. The fine field structure is studied as a function of distance and positions of the source and the receiver. The discreteness of the field structure governed by the deterministic nature of the waveguide is revealed, and the destruction of this structure under the effect of the instability of the waveguide parameters is demonstrated. The effect of the rough sea surface on the sound field in the surface channel is studied, and the diffraction-caused propagation loss is estimated. The mechanism of the forerunner formation is considered. The experimentally observed sound field features are compared with the calculations. A possibility for solving the inverse problem is indicated, and the main parameters that are used in the ray method of determining the source coordinates in the underwater channel (i.e., the method earlier proposed by the author on the basis of the intrinsic structure of the sound field) are pointed out.

Sound Field Features in the Coastal Zone of a Shallow Sea with an Airborne Source of Excitation

Sound Field Features in the Coastal Zone of a Shallow Sea with an Airborne Source of Excitation

Sound Field Features in the Coastal Zone of a Shallow Sea with an Airborne Source of Excitation

Features of the sound field in the coastal zone are theoretically investigated in the case of a moving airborne sound source. It is shown that two factors govern the drastic increase in the signal level measured at the observation point when the source moves near the shoreline: the directional property of the field transmitted from the air into the water and the structure of the normal wave in the wedge near the caustic. The magnitude of the increase in the sound field level depends on the depth of the reception point and, what is more essential, on the structure of the bottom.

Experimental measurements of three-dimensional underwater sound propagation over a variable bathymetry

There appear to be very few experimental measurements of the three-dimensional features of sound fields in the ocean, especially in shallow water where bottom interactions can have a dominant effect. One of the reasons for this lack of experimental data can be attributed to the difficulty in designing an experiment to identify three-dimensional propagation effects. Bathymetric refraction occurs, for the most part, on a very large scale and so to differentiate between local variability of the propagation and refraction by a bathymetric feature, measurements have to be carried out simultaneously over a large area. This is easier to achieve in the laboratory environment where repeatability of the experimental results is not an issue. This paper will describe a series of laboratory scale experiments which were carried out to identify the major features of underwater sound propagation over a realistic three-dimensional bathymetry. The model used is based on the bathymetry of the Santa Lucia Escarpment, but is not unlike bathymetry found in other coastal regions in different water depths if the correct scaling is used. A number of three-dimensional sound maps will be shown of the field from a point source. [Work supported by ONR.]