The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
D D Greenwood - One of the best experts on this subject based on the ideXlab platform.
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erratum and comments re Critical Bandwidth and consonance their operational definitions in relation to cochlear nonlinearity and combination tones hear res 54 209 246 1991
Hearing Research, 1992Co-Authors: D D GreenwoodAbstract:Abstract In a part of the paper cited above, it was suggested that detection of combination components might well determine the initial fall in signal threshold when an experimeter separates two bands of noise masking a signal centered between them-the notched-noise paradigm developed by Patterson (1976). Unfortunately, I mis-stated the Bandwidths of the noise bands used by Patterson despite his clear description of their widths and despite the fact that I have also generated noises in the same way. I erred by stating the Bandwidths to be half of what they were. Given this error, I calculated examples of the cochlear distribution of the combination components that would be produced by Patterson's noise bands, by themselves and in combination with the signal. The calculated combination-band frequency limits and their cochlear positions, using the wrong primary-noise Bandwidth, therefore do not apply to Patterson's experiment. Here the errors are corrected. The modified distribution is not affected in principle. However, for some readers it might seem less probable that detection of combination components in frequency regions lower than the lower band of masking noise could determine the initial fall in threshold (rather than detection of events created by the signal in a cochlear region given by the notch in the two-band masker). But in any case this is an empirical question requiring the direct study that was being urged by the reasoning and calculations presented. There is still reason to suspect that combination tones may have played a role in the two-band experiments, as is illustrated here by figures from Greenwood (1972b) and Krammer (1973) in which the masking stimuli were much narrower. In one figure, given a tone and noise-band masker, a wide array of separated combination bands is generated at lower frequencies, which can mask signals of external origin. They will also either mask, or fail to mask, signal-masker generated combination bands created when an external signal is added in the gap or notch within the two-part primary masker. If signal-masker combination bands are not absolutely everywhere masked by the two-part masker and its combination bands, the signal-masker bands may permit detection of the added signal's presence (thus lowering ‘signal’ threshold). If the masker bands are widened (as by the above corrections, with notch constant), the combination bands generated by them will join and overlap, to mask more uniformly in the lower frequencies, but their distribution will not be the same as if the notch were filled. Whether they will be able everywhere to mask also-wider signal-masker combination bands is the Critical question posed by these figures, which indicate that an experimental study, varying notch and Bandwidth parameters, would be of considerable interest whatever answer emerged.
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Critical Bandwidth and consonance in relation to cochlear frequency position coordinates
Hearing Research, 1991Co-Authors: D D GreenwoodAbstract:Abstract A recent paper (Greenwood, 1990) has reviewed some of the data in the literature on the frequency-position coordinates of the cochlear partition in a number of species and the degree to which they are fitted by empirical functions developed in 1961 (Greenwood, 1961b, 1974b). Continued confirmation by physiological data makes this frequency-position function more independent of non-physiological data and provides a more secure means of testing possible relations of psychoacoustic data to cochlear coordinates. The present paper reviews various sets of Critical band, or similar, data in humans and other species and finds that a considerable body of Bandwidth estimates correspond to equal distances along the cochlear partition (on this assumption), conforming also to an exponential function of distance. As shown in 1961. such a function would imply that the same set of Bandwidths is also a linear function of frequency. Some of the early Critical Bandwidth, and also 'consonant interval', estimates in man correspond to equal distances on the cochlear partition to a degree not generally recognized. Thus above about 300 to 500 Hz most of the Critical band data (of Zwicker and Gassier collated by Zwicker et al., 1957), correspond quite well to equal distances on the Bekesy-Skarstein cochlear map fitted by the frequency-position function, as opposed to the values published in the Critical band table or curve (which do not do so above 3 kHz). Consonant interval data tend to correspond closely to equal distances, from below 100 Hz to about 3 kHz. Certain post-1961 'Critical band' (ERB) estimates collated by Moore and Glasberg (1983) and extended by Moore et al. (1990) and Shailer et al. (1990) also correspond quite closely to constant distances calculated by the 1961 function. So too do some, but not all, of the frequency intervals shown by Plomp (1964) and Plomp and Mimpen (1968) to be required to resolve the components of a harmonic complex. Some Critical Bandwidth data from animal studies may also correspond approximately to equal distances. This survey of old and new results, plotted on a rational distance scale, may assist in explaining what potential mix of factors operates to determine the estimated Bandwidths when the values differ across experiments or in different frequency ranges. The correspondence, in the preponderance of cases, of Critical Bandwidth to a constant distance may facilitate an understanding of the operational definitions of Critical Bandwidth in different experiments and of the common underlying mechanisms. The correspondence is consistent with the basic explanation of Critical Bandwidth and consonance offered in Greenwood (1971, 1972b. 1974b) and Greenwood et al. (1976). The Critical Bandwidths measured in pure-tone masking (the masker-notch interval), two-tone masking, two-tone dissonance-consonance judgments. AM and Quasi-FM detection, narrow-band masking, and two-band (notchednoise) masking reflect a common pattern of nonlinear effects, related to approximately constant 'dimensions' of the region of cochlear nonlinear input-output functions and accelerated phase accumulation (Greenwood, 1974b, 1977), and are codetermined by combination tones and an asymmetrical pattern of suppression (Greenwood and Goldberg, 1970), the latter being incorporated in a gain control mechanism (Greenwood, 1986a, b, c; Greenwood, 1988).
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Critical Bandwidth and consonance their operational definitions in relation to cochlear nonlinearity and combination tones
Hearing Research, 1991Co-Authors: D D GreenwoodAbstract:A recent paper (Greenwood, 1990) reviewed cochlear coordinates in several species in relation to empirical frequency-position functions (Greenwood, 1961b, 1974b), one of which well fits the Bekesy-Skarstein human cochlear map (Bekesy, 1960; Kringlebotn et al, 1979). This increased the independence of the human function from the psychoacoustic data originally used to construct it and encouraged a second assessment of the relations of similar psychoacoustically significant Bandwidths to distance and position on the cochlear map. The companion paper (Greenwood, 1991, this issue), found that, among such Bandwidths, 'classical' Critical Bandwidth, and also 'constant interval', estimates in man correspond to equal distances to a closer extent than generally recognized, and over large parts of the frequency range they conform also to an exponential function of distance, as do most of the ERB estimates. This correspondence to almost constant and similar distances facilitates, and forms a part of, an explanation of the operational definitions of Critical Bandwidth in different experiments. The present account recapitulates the basic explanation of Critical Bandwidth and consonance offered in Greenwood (1971, 1972b, 1973b, 1974b) and Greenwood et al. (1976): by adding schematic details to the earlier account of Critical Bandwidth measurements in pure tone masking (the masker-notch interval), two-tone masking, narrow-band masking, and two-tone dissonance-consonance judgements and by outlining its applicability to AM and Quasi-FM detection and to two-band (nominally notched-noise) masking experiments. The measured Bandwidths derive from approximately uniform dimensions of traveling wave envelopes in the peak region and from the effects of the resulting spatial pattern of nonlinear interference among primary components. In this account, Critical Bandwidth in man corresponds to a distance of about 1 or 1.25 mm, depending upon the direction the interval projects from the stimulus frequency to which it is referenced. It is identified with the apical segment of the traveling wave displacement envelope, which in guinea pig and squirrel monkey appears to be about 2/3rds and 3/4ths of a millimeter, respectively and would be about 1.25 mm in man if these distances were scaled (Greenwood, 1962) among these three species (Greenwood, 1974b, 1977a). When reflected also in the basal direction, the upper end of the frequency interval, at a 1.065 mm distance, makes a total two-Critical-band distance, which corresponds with the region of nonlinear input-output functions that extends in both directions from the envelope peak and hence also with the frequency-dispersive region of accelerated phase accumulation (Greenwood, 1974b, 1977a).(ABSTRACT TRUNCATED AT 400 WORDS)
Prem C Pandey - One of the best experts on this subject based on the ideXlab platform.
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implementation of a digital hearing aid with user settable frequency response and sliding band dynamic range compression as a smartphone app
Intelligent Human Computer Interaction, 2016Co-Authors: Saketh Sharma, Nitya Tiwari, Prem C PandeyAbstract:Persons with sensorineural hearing loss suffer from degraded speech perception caused by frequency-dependent elevation of hearing thresholds, reduced dynamic range and abnormal loudness growth, and increased temporal and spectral masking. For improving speech perception by persons with moderate loss of this type, a digital hearing aid is implemented as an Android-based smartphone app. It uses sliding-band dynamic range compression for restoring normal loudness of low-level sounds without making the high-level sounds uncomfortably loud and for reducing the perceptible temporal and spectral distortions associated with currently used single and multiband compression techniques. The processing involves application of a frequency dependent gain function calculated on the basis of Critical Bandwidth based short-time power spectrum and is realized using FFT-based analysis-synthesis. The implementation has a touch-controlled graphical user interface enabling the app user to fine tune the frequency-dependent parameters in an interactive and real-time mode.
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a smartphone app based digital hearing aid with sliding band dynamic range compression
2016 Twenty Second National Conference on Communication (NCC), 2016Co-Authors: Nitya Tiwari, Prem C Pandey, Anurag SharmaAbstract:Listeners with sensorineural hearing loss have degraded speech perception due to frequency-dependent elevation of hearing thresholds, reduced dynamic range, and increased temporal and spectral masking. Signal processing in hearing aids for such listeners uses frequency-selective amplification and dynamic range compression for restoring normal loudness of low-level sounds without making the high-level sounds uncomfortably loud. Sliding-band compression has been reported earlier for reducing the temporal and spectral distortions generally associated with currently used single and multiband compression techniques. The paper presents implementation of sliding-band compression as a smartphone app for use as a hearing aid. The processing involves a frequency-dependent gain function calculated on the basis of Critical Bandwidth based short-time power spectrum and the specified hearing thresholds, compression ratios, and attack and release times. It is realized using FFT-based analysis-synthesis and can be integrated with other such techniques for computational efficiency.
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multi band frequency compression for improving speech perception by listeners with moderate sensorineural hearing loss
Speech Communication, 2012Co-Authors: Pandurangarao N Kulkarni, Prem C Pandey, Dakshayani S JangamashettiAbstract:In multi-band frequency compression, the speech spectrum is divided into a number of analysis bands, and the spectral samples in each band are compressed towards the band center by a constant compression factor, resulting in presentation of the speech energy in relatively narrow bands, for reducing the effect of increased intraspeech spectral masking associated with sensorineural hearing loss. Earlier investigation assessing the quality of the processed speech showed best results for auditory Critical Bandwidth based compression using spectral segment mapping and pitch-synchronous analysis-synthesis. The objective of the present investigation is to evaluate the effectiveness of the technique in improving speech perception by listeners with moderate to severe sensorineural loss and to optimize the technique with respect to the compression factor. The listening tests showed maximum improvement in speech perception for a compression factor of 0.6, with an improvement of 9%-21% in the recognition scores for consonants and a significant reduction in response times.
Wuchi Feng - One of the best experts on this subject based on the ideXlab platform.
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extending Critical Bandwidth allocation techniques for stored video delivery across best effort networks
International Journal of Communication Systems, 2001Co-Authors: Wuchi Feng, Ming LiuAbstract:In this paper, we propose two new techniques for the delivery of compressed prerecorded video streams across best-effort networks like the Internet. Current approaches for the delivery of stored video across best-effort networks typically alter the quality of the video frames, the frame rate delivered to the user, or a combination of both. By using network feedback, these algorithms continually adjust the video quality to fit within the available network resources. These approaches, however, do not take advantage of the a priori information available from stored video streams, namely the frame sizes that the movie consists of. We will show how monitoring the a priori information and actively monitoring a client-side buffer can help smooth the video frame rate delivered to the user, providing a more consistent quality of video. Copyright © 2001 John Wiley & Sons, Ltd.
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Critical Bandwidth allocation techniques for stored video delivery across best effort networks
International Conference on Distributed Computing Systems, 2000Co-Authors: Wuchi FengAbstract:We propose two new techniques for the delivery of compressed prerecorded video streams across best-effort networks like the Internet. Current approaches for the delivery of stored video across best-effort networks typically alter the quality of the video frames, the frame rate delivered to the user, or a combination of both. By using network feedback, these algorithms continually adjust the video quality to fit within the available network resources. These approaches, however do not take advantage of the a priori information available from stored video streams, namely the frame sizes that the movie consists of. We show how monitoring the a priori information and actively monitoring a client-side buffer can help smooth the video frame rate delivered to the user, providing a more consistent quality of video.
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an optimal Bandwidth allocation strategy for the delivery of compressed prerecorded video
Multimedia Systems, 1997Co-Authors: Wuchi Feng, Farnam Jahanian, Stuart SechrestAbstract:The transportation of prerecorded, compressed video data without loss of picture quality requires the network and video servers to support large fluctuations in Bandwidth requirements. Fully utilizing a client-side buffer for smoothing Bandwidth requirements can limit the fluctuations in Bandwidth required from the underlying network and the video-on-demand servers. This paper shows that, for a fixed-size buffer constraint, the Critical Bandwidth allocation technique results in plans for continuous playback of stored video that have (1) the minimum number of Bandwidth increases, (2) the smallest peak Bandwidth requirements, and (3) the largest minimum Bandwidth requirements. In addition, this paper introduces an optimal Bandwidth allocation algorithm which, in addition to the three Critical Bandwidth allocation properties, minimizes the total number of Bandwidth changes necessary for continuous playback. A comparison between the optimal Bandwidth allocation algorithm and other Critical Bandwidth-based algorithms using 17 full-length movie videos and 3 seminar videos is also presented.
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video on demand services efficient transportation and decompression of variable bit rate video
1996Co-Authors: Wuchi FengAbstract:Digital video compression techniques, such as the Motion-JPEG and MPEG compression standards, greatly reduce the network and storage requirements for digital video. These techniques, however, result in variable-bit-rate video which make the efficient handling and decompression of the video difficult. In this dissertation, we examine how variable-bit-rate digital video affects the ability to efficiently transport and decompress these videos. We introduce two new Bandwidth smoothing techniques that reduce the resource requirements for the transportation of compressed video across networks: the Critical Bandwidth allocation algorithm, which, given a fixed buffer size, creates a Bandwidth plan for the continuous playback of video that (1) requires no prefetching of data, (2) has the minimum number of Bandwidth increases, and (3) minimizes the peak Bandwidth requirements, and the optimal Bandwidth allocation algorithm, which minimizes the total number of Bandwidth changes required for continuous video playback. The use of Bandwidth smoothing techniques in video-on-demand services results in plans that are somewhat inflexible. To allow users to have VCR capabilities in Bandwidth smoothing environments, we analyze the utility of buffered video for decreasing the required interactions with the server. This buffered video, the VCR-window, allows users to have VCR capabilities within a limited without changing the Bandwidth allocation levels. For accesses that cannot be serviced through the smoothing buffer, we show how contingency channels can be used to quickly return users to their original Bandwidth allocation plans. Software video decompression algorithms have poor cache utilizations because of the long time between accesses to temporal data. We examine two techniques for reducing cache misses for software video decompression, reducing the working-set size and using software prefetching. To reduce the working-set size, we introduce several techniques that re-order the decompression algorithm to exploit the temporal accesses to data. These techniques reduce the cache miss rates by over 50% and can result in better performance. In addition, we examine the impact that software-controlled prefetching has on MPEG video decompression. Our results show that sufficient memory Bandwidth exists for prefetching to be beneficial and that miss rates can be reduced by as much as 80%.
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Critical Bandwidth allocation for the delivery of compressed video
Computer Communications, 1995Co-Authors: Wuchi Feng, Stuart SechrestAbstract:The transportation of compressed video data without loss of picture quality requires the network to support large fluctuations in Bandwidth requirements. These fluctuations can be smoothed, but straightforward approaches to smoothing can still suffer from excessive buffering requirements, poor buffer utilization and an excessive number of Bandwidth changes. This paper introduces Critical Bandwidth allocation, which reduces the number of Bandwidth changes to a very small number, and achieves the maximum effectiveness from clientside buffers. A comparison between Critical Bandwidth allocation algorithms and other smoothing algorithms is presented, the sensitivity of the algorithm to jitter is examined, and implications for the design of network services are discussed.
Dakshayani S Jangamashetti - One of the best experts on this subject based on the ideXlab platform.
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multi band frequency compression for improving speech perception by listeners with moderate sensorineural hearing loss
Speech Communication, 2012Co-Authors: Pandurangarao N Kulkarni, Prem C Pandey, Dakshayani S JangamashettiAbstract:In multi-band frequency compression, the speech spectrum is divided into a number of analysis bands, and the spectral samples in each band are compressed towards the band center by a constant compression factor, resulting in presentation of the speech energy in relatively narrow bands, for reducing the effect of increased intraspeech spectral masking associated with sensorineural hearing loss. Earlier investigation assessing the quality of the processed speech showed best results for auditory Critical Bandwidth based compression using spectral segment mapping and pitch-synchronous analysis-synthesis. The objective of the present investigation is to evaluate the effectiveness of the technique in improving speech perception by listeners with moderate to severe sensorineural loss and to optimize the technique with respect to the compression factor. The listening tests showed maximum improvement in speech perception for a compression factor of 0.6, with an improvement of 9%-21% in the recognition scores for consonants and a significant reduction in response times.
Pandurangarao N Kulkarni - One of the best experts on this subject based on the ideXlab platform.
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multi band frequency compression for improving speech perception by listeners with moderate sensorineural hearing loss
Speech Communication, 2012Co-Authors: Pandurangarao N Kulkarni, Prem C Pandey, Dakshayani S JangamashettiAbstract:In multi-band frequency compression, the speech spectrum is divided into a number of analysis bands, and the spectral samples in each band are compressed towards the band center by a constant compression factor, resulting in presentation of the speech energy in relatively narrow bands, for reducing the effect of increased intraspeech spectral masking associated with sensorineural hearing loss. Earlier investigation assessing the quality of the processed speech showed best results for auditory Critical Bandwidth based compression using spectral segment mapping and pitch-synchronous analysis-synthesis. The objective of the present investigation is to evaluate the effectiveness of the technique in improving speech perception by listeners with moderate to severe sensorineural loss and to optimize the technique with respect to the compression factor. The listening tests showed maximum improvement in speech perception for a compression factor of 0.6, with an improvement of 9%-21% in the recognition scores for consonants and a significant reduction in response times.