Sound field reproduction using multilayer equivalent source method
Time: 6:00 am
Author: Xi Hong
Abstract ID: 1438
Sound field reproduction aims to create or reproduce a desired sound environment, where both the audio content and the spatial property of the sound field are preserved. For a practical reproduction system which is usually placed in a real listening room, acoustic transfer function measurement of the loudspeaker array is a time consuming work. The equivalent source method is an option to interpolate loudspeaker array acoustic transfer functions over the target region in reverberant sound field and has been implemented in the preceding researches. However, the selection of the optimized distances of the equivalent sources remains a challenging problem, especially considering the complex acoustic environment in reverberant room. In this work, we apply a multilayer equivalent source method. A simulation is conducted in virtual listening rooms with different reverberation conditions to investigate the reproduction performance of the proposed method. The comparison with the conventional single layer equivalent source method is provided.
A two-zone sound field reproduction based on the region energy control
Time: 6:20 am
Author: Bokai Du
Abstract ID: 1442
Multizone sound field reproduction aims to create different acoustical environments in regions without physical isolation. For a real reproduction system, it is always expected to improve system performance and reduce measurement effort. In this paper, a two-zone sound field reproduction is investigated with a proposed region control method. Conventional multipoint method only controls sound field at limited number of measurement points. However, the proposed method tries to control the sound field energy over the whole region. Considering the systems diverse work environment, different interpolation methods are applied in the proposed method. Simulations are conducted under free field and reverberation condition in order to deeply compare with conventional method and another harmonic domain method. Simulation results show that the proposed method achieves better performance than the conventional multipoint method in free field and reverberant environment. On the other hand, the region control method proposed in this paper is free from microphone array geometry requirement, which means the method is more convenient for the practical application.
Upper hemisphere sound image control with horizontal-arranged loudspeakers based on parametric head-related transfer functions
Time: 7:00 am
Author: Syumpei Miura
Abstract ID: 1749
The 22.2 multichannel sound system has been developed for an ultra high-definition television system. This system consists of twenty two loudspeakers and two sub-woofers called low frequency effects, and can reproduce three-dimensional sound image appropriate to the ultra high-definition television system. However, this system has a problem of high cost to install. On the other hand, the multichannel sound system with horizontal-arranged loudspeakers has lower cost to install than full scale one. However, this system cannot reproduce an upper sound image. Therefore, in this paper, we propose the upper sound image control with horizontal-arranged loudspeakers based on the parametric head-related transfer functions. The proposed method generates binaural signals to control the sound image elevationally based on the parametric head-related transfer functions in the median plane. Also, the proposed system uses the interaural level difference to control the sound image of binaural signals azimuthally. Finally, the proposed method generates output signals for horizontal-arranged loudspeakers from binaural signals by designing a multichannel inverse system based on multi-input / output inverse theorem. The experimental results show that the proposed method can control the sound image to elevation angle with the same accuracy as binaural lreproduction. The 22.2 multichannel sound system has been developed for an ultra high-definition television system. This system consists of twenty loudspeakers and two sub-woofers called low frequency effects, and can reproduce three-dimensional sound image appropriate to the ultra high-definition television system. However, this system has a problem of high cost to install. On the other hand, the multichannel sound system with horizontal-arranged loudspeakers has lower cost to install than full scale one. However, this system cannot reproduce an upper sound image. Therefore, in this paper, we propose the upper sound image control with horizontal-arranged loudspeakers based on the parametric head-related transfer functions. The proposed method generates binaural signals to control the sound image elevationally based on the parametric head-related transfer functions in the median plane. Also, the proposed system uses the interaural level difference to control the sound image of binaural signals azimuthally. Finally, the proposed method generates output signals for horizontal-arranged loudspeakers from binaural signals by designing a multichannel inverse system based on multi-input / output inverse theorem. The experimental results show that the proposed method can control the sound image to elevation angle with the same accuracy as binaural reproduction.
3-D sound field reproduction with reverberation control on surround sound system by combining parametric and electro-dynamic loudspeakers
Time: 2:20 pm
Author: Yuna Harada
Abstract ID: 1751
Recently, with the development of video technology, 3-D sound field reproduction systems that can provide a high presence have attracted attention. Conventional systems with electro-dynamic loudspeakers have a problem that the sound image lacks sharpness when constructing a narrow sound image. To solve this problem, we utilize a parametric array loudspeaker which has sharp directivity by the straightness of ultrasounds. Parametric array loudspeakers can produce sharper sound images due to the sharper directivity and lower reverberation compared with electro-dynamic loudspeakers. However, it is difficult to represent reverberation by parametric array loudspeakers. In this paper, we propose a method for 3-D sound field reproduction to achieve both the sharp images and reverberation presence by combing parametric array loudspeakers and electro-dynamic loudspeakers in surround sound system. In the proposed method, sharp sound images are rendered by parametric array loudspeakers and the reverberation presence is provided by electro-dynamic loudspeakers, emitting reverberation signals synthesized with a reverberation control filter. The reverberation control filter is adaptively designed to reproduce the reverberation time and the direct-to-reverberation ratio of the target sound field in other environments. The experimental results show that the proposed method can achieve the reproducing the sharp sound image with some reverberation presence.
Head related transfer function measurements of common PPE
Time: 8:20 pm
Author: Megan Ewers
Abstract ID: 2134
Due to COVID 19, personal protective equipment (PPE) is now used in everyday life. Such PPE affects communication and perception. This paper provides an overview of the impact of PPE on Head Related Transfer Functions (HRTFs). Spatial acoustic effects of common PPE on human hearing can be documented to improve and inform field worker safety and communication. After a general description of the measurement process and required tools, we focus on a few methods which contribute significantly to the accuracy and analysis of PPE-based HRTF data. The dedicated setup allows measuring a full 360 degree map in automated fashion. It includes a special ring setup with 25 speakers, and a precise turn table that is used to adjust the angle of the device under test with respect to the ring. Binaural measurements were performed on a set of common PPE items on a Head And Torso Simulator (HATS) system, including hard hats, safety glasses, hearing protection, and various face masks. An overview of the data is presented.
Comparative study of loudspeaker position optimization techniques for multizone sound field reproduction
Time: 6:40 am
Author: Sipei Zhao
Abstract ID: 2150
Mutlizone sound field reproduction aims to generate personal sound zones in a shared space with multiple loudspeakers. Conventionally, loudspeakers are placed to form a regular pattern such as circular, arc or linear array, which are empirical rather than optimal mainly for the convenience of physical placement. Recently, several algorithms have been proposed to select a fixed number of loudspeaker locations from a large set of candidate positions, such as the sparse regularization methods (i.e. Lasso and Elastic Net), the Constrained Match Pursuit method, the Gram-Schmidt Orthogonalization method . Most of these methods were investigated for single-zone rather than mulit-zone sound field reproduction based on the pressure matching techniques. This paper compares the performance of the state-of-the-art techniques for loudspeaker position optimization in a multizone sound field reproduction system in terms of reproduction error, acoustic contrast and array effort. Both single tone and broadband sound signals are used and the effect of the distance between the bright and dark zones on the performance of the algorithms are investigated.
Precision of inertial measurement unit sensors in head-tracking systems used for binaural synthesis
Time: 3:20 pm
Author: Kristian Jambrosic
Abstract ID: 2190
Binaural synthesis is the most used sound system for diverse virtual and augmented reality systems nowadays, given its simplicity of implementation and the need of using only two audio channels. It is widely used in computer games, auralization and even audio production. To achieve the most natural sound field recreation, systems used for binaural synthesis must include a head-tracking sensor to dynamically calculate the binaural signal for the head orientation at any given moment. This is done by inertial measurement unit (IMU) sensors, specifically the triaxial accelerometers, gyroscopes, and magnetometers. Simpler systems, e.g., Arduino or other embedded systems, provide only raw sensor data, and the orientation is calculated by a processing unit. Other, more complex systems such as smartphones or VR headsets already calculate their position from the raw data using complex sensor integration algorithms. In this paper, a measurement procedure for measuring the precision of IMU sensors is presented. The need of absolute orientation calibration is addressed, and challenges of sensor data drift are discussed. Measurement results for simple embedded systems and complex systems found in smartphones are presented, and an estimation of IMU sensor quality for binaural synthesis is made.
Regularized spherical harmonics-domain spatial active noise cancellation in a reverberant room
Time: 2:40 pm
Author: Shoken Kaneko
Abstract ID: 2820
Active Noise Cancellation (ANC) at a target area in an open space, as opposed to cancellation in the ears through headphones, can lead to future applications. For instance, a personal acoustic environment in an airplane seat or inside a car, or a quiet zone in a noisy shared workspace can be possible using such open-space ANC without any uncomfortable on-body audio equipment. Recent advancements reinforce the practicality of such systems. However, regularization of the cancellation signal has been a crucial challenge in open-space ANC as it causes amplification of noise at locations away from the target area. This work presents a spherical harmonics-domain feed-forward spatial ANC method with a room-wide global cost function to address this issue. This room-wide global cost function is used for optimizing the set of regularization hyperparameters, while at run time only local information captured by a microphone array surrounding the target listening zone is required. Numerical experiments applying the proposed method in a simulated reverberant room show the effectiveness of the proposed method in creating a specific zone of silence with low to moderate noise amplification in the rest of the room.
Head tracker using webcam for auralization
Time: 3:00 pm
Author: William D'Andrea Fonseca
Abstract ID: 2956
Binaural rendering is a technique that seeks to generate virtual auditory environments that replicate the natural listening experience, including the three-dimensional perception of spatialized sound sources. As such, real-time knowledge of the listener's position, or more specifically, their head and ear orientations allow the transfer of movement from the real world to virtual spaces, which consequently enables a richer immersion and interaction with the virtual scene. This study presents the use of a simple laptop integrated camera (webcam) as a head tracker sensor, disregarding the necessity to mount any hardware to the listener's head. The software was built on top of a state-of-the-art face landmark detection model, from Google's MediaPipe library for Python. Manipulations to the coordinate system are performed, in order to translate the origin from the camera to the center of the subject's head and adequately extract rotation matrices and Euler angles. Low-latency communication is enabled via User Datagram Protocol (UDP), allowing the head tracker to run in parallel and asynchronous with the main application. Empirical experiments have demonstrated reasonable accuracy and quick response, indicating suitability to real-time applications that do not necessarily require methodical precision.