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J Ben-Arie

Publications and source records attributed to J Ben-Arie.

10 recordsLinked to original sources
PubMed1996

Optimal head related transfer functions for hearing and monaural localization in elevation: a signal processing design perspective.

Localization of sound sources by human listeners has been widely studied and theories and various models of the localization and hearing mechanism have been constructed. In the classical "duplex" theory, sound localization in azimuth is explained by interaural time or equivalently, phase differences at low frequencies, and by interaural amplitude differences at higher frequencies. Head related transfer functions (HRTF's) present a linear system approach to modeling localization by representing the direction-dependent transformation the sound undergoes at each ear. Localization in elevation is explained by directional differences in the HRTF's, which also explains monaural localization. We conjecture that the HRTF's evolved during the course of nature (due to the evolution of the shape and structure of the ear etc.) are optimal with respect to several physically realizable criteria. In this paper, we investigate the problem of defining the design constraints which when optimized yield a set of HRTF's for hearing and monaural vertical localization in an attempt to better understand, and if possible, duplicate nature's design. We pursue an engineer's design perspective and formulate a constrained optimization problem, where the desired set of HRTF's is optimized according to a cost function based on several criteria for localization, hearing and smoothness, and also by imposing physically realizable constraints on the HRTF's such as nonnegativity, energy etc. The value of the cost function for a candidate set of HRTF's is an indication of the similarity of that set of HRTF's with respect to the ideal solution (measured HRTF data). The final optimization results we present are similar to the actual HRTF's measured in human subjects, and the associated cost function values are found to be almost equal. This points to the fact that the optimization criteria defined are quite relevant. The significant outcome of this research is the identification of a relevant set of mathematical criteria that could be optimized in the human auditory system to facilitate good hearing and localization. These criteria along with the associated constraints represent the desirable characteristics of the HRTF's in an HRTF-based localization system, and could lead to a better understanding and modeling of the auditory system.

Algorithms↗
PubMed1993

[Hodgkin's disease in childhood--northern Israel cancer center experience, 1971-1990].

Records of children treated for Hodgkin's disease between 1971-1990 were analyzed retrospectively, and 102 cases of children younger than 18 years when diagnosed were reviewed. There were 54 boys and 48 girls, with male predominance in those younger than 10 years. 44 patients were of Arab ancestry and 58 were Jewish; the incidence was similar in both groups. Most common were the nodular sclerosing and mixed cellularity types, the latter more common in the younger age group. The outcome of various treatments was evaluated. At diagnosis, 64% were in stages I or II and 34% in stages III or IV. 20 of those in stages I-II received radiotherapy (RT) alone, 10 chemotherapy (CT) alone, and 35 combined CT and RT. Survival rates and median disease-free intervals were statistically similar with all 3 modalities. However, relapse rates were higher with either RT or CT alone (35% and 38%, respectively) than with combined therapy (14%). We conclude that combined CT and RT is superior to RT or CT alone.

Adolescent↗
PubMed1981

Spinal intradural metastases of extraneural origin.

Three cases of intradural extramedullary (spinal subdural) metastases, originating from outside the central nervous system, are presented. Two were located at the cervico-dorsal junction, and one was mid-dorsal. A breast ductus carcinoma, a cervical neuroblastoma, and an apoduma of unknown origin, were the primary neoplasms. All presented clinically with a short history typical of cancerous spinal cord compression. Plain X-rays of the spine did not show areas of destruction. Myelography in two cases clearly suggested that intradural location of the tumour. The relative frequency of these tumours and their pathogenesis are briefly reviewed. It is stressed that primary tumours are mainly in the breast or lung. Their metastases are mainly found in the cervico-dorsal region. It is assumed that they really are metastases of the dura mater itself, growing inward. The importance of the lymphatic and venous pathways in their spread into the dura mater is emphasized.

Adult↗
PubMedDate not supplied

An auditory localization model based on high-frequency spectral cues.

We present in this paper a connectionist model that extracts interaural intensity differences (IID) from head-related transfer functions (HRTF) in the form of spectral cues to localize broadband high-frequency auditory stimuli, in both azimuth and elevation. A novel discriminative matching measure (DMM) is defined and optimized to characterize matching this IID spectrum. The optimal DMM approach and a novel back-propagation-based fuzzy model of localization are shown to be capable of localizing sources in azimuth, using only spectral IID cues. The fuzzy neural network model is extended to include localization in elevation. The use of training data with additive noise provides robustness to input errors. Outputs are modeled as two-dimensional Gaussians that act as membership functions for the fuzzy sets of sound locations. Error back-propagation is used to train the network to correlate input patterns and the desired output patterns. The fuzzy outputs are used to estimate the location of the source by detecting Gaussians using the max-energy paradigm. The proposed model shows that HRTF-based spectral IID patterns can provide sufficient information for extracting localization cues using a connectionist paradigm. Successful recognition in the presence of additive noise in the inputs indicates that the computational framework of this model is robust to errors made in estimating the IID patterns. The localization errors for such noisy patterns at various elevations and azimuths are compared and found to be within limits of localization blurs observed in humans.

Ear↗