A five-channel microphone system for detecting 3-D acoustic image sources
0
Citation
0
Reference
10
Related Paper
Abstract:
Measuring three-dimensional behavior of early reflections in a sound field has been an important issue in auditorium acoustics, since they are found to be strongly correlated with the subjective experience of spatial impression in rooms. A conventional way of detecting the direction and relative amplitude of reflections is to utilize a four-channel microphone system. This system, however, has the inherent possibility of missing some important reflections while exploring the early part of reflections. A new measurement system, which has five microphones on the apex of a tetrahedron and at the center of gravity, is proposed in the present work. The proposed system enables us to find more early reflections accurately, which previous four-channel microphone systems might miss. A peak detecting pair matching algorithm, which gives dominant peaks of impulse response automatically by typical iteration, was adopted, since we should find exact peak positions of measured impulse response in order to calculate source positions accurately. In the present paper, the theoretical backgrounds and features of the five-channel microphone system are presented. Also, some results from experiments using the system are discussed. Experimental results clearly show the advantage of the five-channel microphone system over the conventional four-channel microphone system. [Work supported by Korean Research Foundation Grant KRF-1999-1-310-004-3.]Keywords:
Impulse response
The authors present the result of their research on developing a hands-free voice communication system with a microphone array for use in an automobile environment. The goal of this research is to develop a speech acquisition and enhancement system so that a speech recognizer can reliably be used inside a noise automobile environment, for digital cellular phone application. Speech data have been collected using a microphone array and a digital audio tape (DAT) recorder inside a real car for several idling and driving conditions, and processed using delay-and-sum and adaptive beamforming algorithms. Performance criteria including signal-to-noise ratio and speech recognition error rate have been evaluated for the processed data. Detailed performance results presented show that the microphone array is superior to a single microphone.< >
Noise-canceling microphone
SIGNAL (programming language)
Cite
Citations (50)
Impulse responses of the piezoelectric photoacoustic (PA) signal have been measured by using the technique of cross correlation. Experimental impulse responses of aluminum model samples are in good agreement with theoretical prediction. It is shown that thermal diffusivities of opaque materials can be determined by measured zero-crossing times of PA impulse response. Cracks in aluminum samples are detected by measuring a one-dimensional image of the impulse response of the PA signal.
Impulse response
SIGNAL (programming language)
Photoacoustic effect
Cite
Citations (5)
This paper presents a study that uses only a single microphone for direction of arrival (DOA) estimation, as opposed to a microphone array. The proposed method utilises a circularly moving microphone; exploiting the Doppler effect produced by the motion along the circular path to find the DOA. Being inspired by a previous study which utilised a microphone array with circular sampling, the change in instantaneous frequency of the signal is estimated using the Centre of Gravity algorithm. The method is tested by both numerical simulations and practical experiments. A practical recording device that has a rotating disc with a microphone embedded was designed, developed, and utilised for the experiments. The results suggest the DOA can be estimated accurately when the frequency of the sound source is high.
Direction of arrival
SIGNAL (programming language)
Noise-canceling microphone
Cite
Citations (5)
Using spherical microphone arrays to form directed beams is becoming an important technology in sound field analysis, teleconferencing, and surveillance systems. Moreover, in scenarios for capturing musical content, the recording and post-production process could be simplified through flexible beamforming technology. Often, audio engineers favor the use of conventional recording microphones over spherical microphone arrays which might be due to the engineer's preference for distinct spatial and timbral characteristics of different microphone types and brands. We present an approach to create beamforming pattern using a 144 channel spherical microphone array, which aims to match the distinct spatial and timbral characteristics of classic microphones. For this, we first measured the spatial and timbral characteristics of several classic microphones types as well as the characteristics of our spherical microphone array in an anechoic chamber. Using a regularized least-square approach, these data were then used for computing the filters for the spherical microphone array that forms the desired beams. We show the results of several microphone-beam simulations and compare them with the impulse responses of the original classic microphones. Advantages and limitations of our approach will be discussed.
Noise-canceling microphone
Anechoic chamber
Impulse response
Cite
Citations (0)
Microphone arrays are becoming increasingly popular for conferencing applications and near-field speech recording. In this work, a 16-element cylindrical microphone array is designed for beamforming towards a nearby speaker, while reducing the influence of competing talkers. A two-stage approach is used to obtain the desired array directivity pattern, optimizing both microphone locations and filter weights. The positions of the microphones are optimized by using a hybrid optimization technique, taking into account the influence of the nearby acoustic environment. FIR filter coefficients for each microphone are derived from a regularized least-squares (LSQR) solution, combined with null-steering. The performance of the design is evaluated experimentally and compared with a classically used goose-neck microphone.
Noise-canceling microphone
Directivity
Cite
Citations (1)
In previous studies, the localisation accuracy and the spatial impression of 3-2 stereo microphone arrays were discussed. These showed that 3-2 stereo cannot produce stable images to the side and to the rear of the listener. An octagon loudspeaker array was therefore proposed. Microphone array design for this loudspeaker configuration was studied in terms of localisation accuracy, locatedness and sound image width. This paper describes an experiment conducted to evaluate the spaciousness of 10 different microphone arrays used in different acoustical environments. Spaciousness was analyzed as a function of sound signal, acoustical environment and microphone array’s characteristics. It showed that the height of the microphone array and the original acoustical environment are the two variables that have the most influence on the perceived spaciousness, but that microphone directivity and the position of sound sources is also important.
Directivity
Noise-canceling microphone
Impression
Cite
Citations (1)
The paper presents the acoustic source localization in a 2D rectangular room by using the measured acoustic impulse response. Two cases are considered: a corner of a room and a corridor. In each case, a theoretical analysis based on image source model is presented. To identify the source position, until some ambiguities, a single acoustic impulse response is required. To overcome these ambiguities, two additional impulse responses are needed. The three impulse responses can be obtained in the same time or by sequential measurements, two at a time. Experimental results obtained by real measurements which prove the theoretical ideas are presented.
Impulse response
Cite
Citations (1)
The capture of the spatial structure of a sound field and analysis is important in many fields including creating virtual environments, source localization and detection, noise suppression, and beamforming. Spherical microphone arrays are a promising development to help achieve such capture and analysis, and have been studied by several groups. We develop a practical spherical microphone array and demonstrate its utility in applications for sound capture, room measurement and for beamforming and tracking. To accommodate equipment failure and manufacturing imprecision we extend their theory to handle arbitrary microphone placement. To handle speech capture and surveillance we describe the development of a new sensor, the hemispherical microphone array. For each array the practical performance follows that predicted by theory. Future applications and improvements are also discussed. [Work supported by NSF.]
Noise-canceling microphone
Tracking (education)
Cite
Citations (1)
Many multi-microphone speech enhancement algorithms require the relative transfer function (RTF) vector of the desired speech source, relating the acoustic transfer functions of all array microphones to a reference microphone. In this paper, we propose a computationally efficient method to estimate the RTF vector in a diffuse noise field, which requires an additional microphone that is spatially separated from the microphone array, such that the spatial coherence between the noise components in the microphone array signals and the additional microphone signal is low. Assuming this spatial coherence to be zero, we show that an unbiased estimate of the RTF vector can be obtained. Based on real-world recordings experimental results show that the proposed RTF estimator outperforms state-of-the-art estimators using only the microphone array signals in terms of estimation accuracy and noise reduction performance.
Noise-canceling microphone
SIGNAL (programming language)
Cite
Citations (12)
Sound source localization using a microphone array embedded on an unmanned aerial vehicle has been studied to detect and localize people who need help in a disaster-stricken area. Because such sound source localization should work in outdoor environments, the design of the microphone array is crucial. We thus developed two types of microphone array; 16ch two-storied hexagonal and 12ch spherical microphone arrays. These two microphone arrays were evaluated via numerical simulation with discussions on the appropriate design of microphone arrays.
Noise-canceling microphone
Cite
Citations (1)