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Robert P Carlyon - One of the best experts on this subject based on the ideXlab platform.
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a re examination of the effect of masker phase curvature on non Simultaneous Masking
Jaro-journal of The Association for Research in Otolaryngology, 2017Co-Authors: Robert P Carlyon, Sheila Flanagan, John M DeeksAbstract:Forward Masking of a sinusoidal signal is determined not only by the masker’s power spectrum but also by its phase spectrum. Specifically, when the phase spectrum is such that the output of an auditory filter centred on the signal has a highly modulated (“peaked”) envelope, there is less Masking than when that envelope is flat. This finding has been attributed to non-linearities, such as compression, reducing the average neural response to maskers that produce more peaked auditory filter outputs (Carlyon and Datta, J Acoust Soc Am 101:3636–3647, 1997). Here we evaluate an alternative explanation proposed by Wotcjzak and Oxenham (Wojtczak and Oxenham, J Assoc Res Otolaryngol 10:595–607, 2009). They reported a masker phase effect for 6-kHz signals when the masker components were at least an octave below the signal frequency. Wotcjzak and Oxenham argued that this effect was inconsistent with cochlear compression, and, because it did not occur at lower signal frequencies, was also inconsistent with more central compression. It was instead attributed to activation of the efferent system reducing the response to the subsequent probe. Here, experiment 1 replicated their main findings. Experiment 2 showed that the phase effect on off-frequency forward Masking is similar at signal frequencies of 2 and 6 kHz, provided that one equates the number of components likely to interact within an auditory filter centred on the signal, thereby roughly equating the effect of masker phase on the peakiness of that filter output. Experiment 3 showed that for some subjects, masker phase also had a strong influence on off-frequency backward Masking of the signal, and that the size of this effect correlated across subjects with that observed in forward Masking. We conclude that the masker phase effect is mediated mainly by cochlear non-linearities, with a possible additional effect of more central compression. The data are not consistent with a role for the efferent system.
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effects of aspirin on human psychophysical tuning curves in forward and Simultaneous Masking
Hearing Research, 1996Co-Authors: Hazel A Beveridge, Robert P CarlyonAbstract:Psychophysical tuning curves (PTCs) at 4 kHz were measured in forward and Simultaneous Masking under two experimental conditions: 1 h after listeners had ingested three 320 mg capsules of aspirin every 6 h for 3 days (3.84 g/day), and after an identical schedule of placebo ingestion. Aspirin and placebo allocation was double-blind. In addition to raising thresholds at several audiometric frequencies, aspirin elevated the tips and reduced the slopes of the PTCs, indicating a reduction in frequency selectivity. The aspirin-induced reduction in PTC slopes did not differ significantly between forward and Simultaneous Masking, nor did the overall reduction differ significantly between the low- and high-frequency side. However, a separate analysis of the data obtained in Simultaneous Masking indicated that the broadening in tuning caused by aspirin was greatest on the high-frequency side of the PTC.
Sid P Bacon - One of the best experts on this subject based on the ideXlab platform.
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the effect of a steep high frequency hearing loss on growth of Masking functions in Simultaneous Masking for fm fs
Hearing Research, 2005Co-Authors: Rene H Gifford, Sid P BaconAbstract:Abstract In normal-hearing subjects, the slope of the growth-of-Masking (GOM) function obtained in Simultaneous Masking when the masker frequency (fm) is much less than the signal frequency (fs) often changes from a value near 2.0 to a value near 1.0 at high levels. The purpose of the present study was to evaluate whether this change in slope reflects a basal shift in the peak of the signal’s basilar-membrane vibration pattern. To discourage the use of basally shifted peak excitation, GOM functions were obtained in seven subjects with a precipitously sloping high-frequency hearing loss. The signal was located at the normal-hearing edge of the loss, and the masker was located 3 equivalent rectangular bandwidths below fs. In addition, GOM functions for an fs of 2000 Hz were obtained in four subjects with normal hearing, either “in quiet” or in the presence of a restrictor tone with a frequency of 2400 or 2600 Hz and a level of 90 dB SPL. Overall, the results generally are not consistent with the change in slope at high levels being due to a basal shift in the peak of the signal’s basilar-membrane vibration pattern. Instead, the results are consistent with a decrease in compression at high input levels at the place corresponding to fs.
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temporal effects in Simultaneous Masking with on and off frequency noise maskers effects of signal frequency and masker level
Journal of the Acoustical Society of America, 2004Co-Authors: Sid P Bacon, Sophie SavelAbstract:Temporal effects in Simultaneous Masking were measured as a function of masker level for an on-frequency broadband masker and an off-frequency narrow-band masker for signal frequencies of 750, 1730, and 4000 Hz. The on-frequency masker was 10 equivalent rectangular bandwidths (ERBs) wide and centered at the signal frequency; the off-frequency masker was 500 Hz wide and its lower frequency edge was 1.038 ERBs higher in frequency than the signal. The primary goal of the study was to determine whether previously observed differences regarding the effects of signal frequency and masker level on the temporal effect for these two different types of masker might be due to considerably different signal levels at threshold. Despite similar masked thresholds, the effects of signal frequency and masker level in the present study were different for the two masker types. The temporal effect was significant for the two highest frequencies and absent for the lowest frequency in the presence of the broadband masker, but was more or less independent of frequency for the narrow-band masker. The temporal effect increased but then decreased as a function of level for the broadband masker (at the two higher signal frequencies, where there was a temporal effect), but increased and reached an asymptote for the narrow-band masker. Despite the different effects of signal frequency and masker level, the temporal effects for both types of masker can be understood in terms of a basilar-membrane input–output function that becomes more linear during the course of masker stimulation.
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effects of signal delay on auditory filter shapes derived from psychophysical tuning curves and notched noise data obtained in Simultaneous Masking
Journal of the Acoustical Society of America, 2002Co-Authors: Sid P Bacon, Jennifer L Repovschduffey, Li LiuAbstract:Psychophysical tuning curves (PTCs) measured in Simultaneous Masking usually sharpen as a short duration signal is moved from the onset to the temporal center of a longer duration masker. Filter shapes derived from notched-noise maskers have not consistently shown this effect. One possible explanation for this difference is that the signal level is fixed in the PTC paradigm, whereas the masker level is usually fixed in the notched-noise paradigm. In the present study, the signal level was fixed at 10 dB SL in both paradigms. The signal was 20 ms in duration, and presented at the onset or temporal center of the 400-ms masker. The masker was a pure tone presented in quiet (PTC) or in the presence of a pure-tone “restrictor” intended to limit off-frequency listening (PTCr), or it was a noise with a spectral notch placed symmetrically or asymmetrically about the 2-kHz signal frequency. Filter shapes were derived from the PTC, PTCr, and notched-noise data using the roex (p, w, t) model. The effects of signal delay and Masking paradigm on filter bandwidth were analyzed with a two-factor repeated-measures ANOVA. There was a significant effect of signal delay (the filters sharpened with time) and Masking paradigm (the filters derived from the notched-noise data were significantly wider than those derived from either of the PTC measurements, which did not differ from one another). Although the interaction between delay and paradigm was not significant, the filter derived from the notched-noise data sharpened more with time than did the other filters, and thus the bandwidth of the filters from the three paradigms were more similar at the longer delay than at the shorter delay. It is likely that the tuning-curve and notched-noise paradigms measure the same underlying filtering, but that various other factors contribute differentially to the derived filter shapes.
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the influence of aspirin on temporal effects in Simultaneous Masking with noise and tonal maskers
Journal of the Acoustical Society of America, 2000Co-Authors: Sid P Bacon, Michelle L HicksAbstract:Temporal effects in Simultaneous Masking were measured before and during the administration of a moderate dose of aspirin that caused about 5–15 dB of temporary hearing loss. The 10‐ms, 4.0‐kHz signal was presented at the beginning or in the temporal center of a 400‐ms masker. The masker was either a broadband noise presented at a spectrum level of 10 or 20 dB SPL or a tone with a frequency of 5.2, 5.4, or 5.6 kHz presented at a level of 80 dB SPL. Consistent with previous results [D. McFadden and C. A. Champlin, J. Acoust. Soc. Am. 87, 2634–2642 (1990)], aspirin tended to reduce the temporal effect with the broadband masker (i.e., the overshoot) by decreasing the threshold for the signal at masker onset. Aspirin also tended to reduce the temporal effect in the presence of the tonal masker, but in this case by increasing the threshold for the signal in the temporal center and, to a lesser extent, at masker onset. This differential effect of aspirin suggests that the mechanisms underlying the two temporal effects may differ. [Work supported by NIDCD.]
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contributions of suppression and excitation to Simultaneous Masking effects of signal frequency and masker signal frequency relation
Journal of the Acoustical Society of America, 2000Co-Authors: Rene H Gifford, Sid P BaconAbstract:This study investigated the contributions of suppression and excitation to Simultaneous Masking for a range of masker frequencies both below and above three different signal frequencies (750, 2000, and 4850 Hz). A two-stage experiment was employed. In stage I, the level of each off-frequency Simultaneous masker necessary to mask a signal at 10 or 30 dB sensation level was determined. In stage II, three different forward-Masking conditions were tested: (1) an on-frequency condition, in which the signals in stage I were used to mask probes of the same frequency; (2) an off-frequency condition, in which the off-frequency maskers (at the levels determined in stage I) were used to mask the probes; and (3) a combined condition, in which the on- and off-frequency maskers were combined to mask the probes. If the off-frequency maskers Simultaneously masked the signal via spread of excitation in stage I, then the off-frequency and combined maskers should produce considerable forward Masking in stage II. If, on the other hand, they masked via suppression, they should produce little or no forward Masking. The contribution of suppression was found to increase with increasing signal frequency; it was absent at 750 Hz, but dominant at 4850 Hz. These results have implications for excitation pattern analyses and are consistent with stronger nonlinear processing at high rather than at low frequencies.
Matthew L Bolton - One of the best experts on this subject based on the ideXlab platform.
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a computationally efficient formal method for discovering Simultaneous Masking in medical alarms
Applied Acoustics, 2018Co-Authors: Matthew L Bolton, Judy Edworthy, Andrew D Boyd, Jiajun Wei, Xi ZhengAbstract:Abstract Numerous patient injuries and deaths have been caused by medical practitioners failing to respond to medical alarms. Simultaneous Masking, where concurrently sounding medical alarms result in one or more being unhearable, is partially responsible for this problem. In previous work, we introduced a computational formal method capable of proving (formally verifying) if Masking could occur in a modeled configuration of medical alarms. However, the scalability of the method limited the applicability and completeness of its analyses. In the work presented here, we show how we re-implemented the method to address these shortcomings. We evaluated the detection capabilities and scalability of the new version of the method with a series of realistic and synthetic case studies. Our results show that the new version of the method replicates and improves detection capabilities compared to the legacy method and does so with significant reductions in verification times. We discuss the patient safety implications of our results and explore directions for future research.
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a formal approach to discovering Simultaneous additive Masking between auditory medical alarms
Applied Ergonomics, 2017Co-Authors: Bassam Hasanain, Andrew D Boyd, Judy Edworthy, Matthew L BoltonAbstract:The failure of humans to respond to auditory medical alarms has resulted in numerous patient injuries and deaths and is thus a major safety concern. A relatively understudied source of response failures has to do with Simultaneous Masking, a condition where concurrent sounds interact in ways that make one or more of them imperceptible due to physical limitations of human perception. This paper presents a method, which builds on a previous implementation, that uses a novel combination of psychophysical modeling and formal verification with model checking to detect Masking in a modeled configuration of medical alarms. Specifically, the new method discussed here improves the original method by adding the ability to detect additive Masking while concurrently improving method usability and scalability. This paper describes how these additions to our method were realized. It then demonstrates the scalability and detection improvements via three different case studies. Results and future research are discussed.
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Using Model Checking to Detect Simultaneous Masking in Medical Alarms
IEEE Transactions on Human-Machine Systems, 2016Co-Authors: Bassam Hasanain, Andrew D Boyd, Matthew L BoltonAbstract:The ability of people to hear and respond to auditory medical alarms is critical to the health and safety of patients. Unfortunately, concurrently sounding alarms can perceptually interact in ways that mask one or more of them: making them impossible to hear. Because Masking may only occur in extremely specific and/or rare situations, experimental evaluation techniques are insufficient for detecting Masking in all of the potential alarm configurations used in medicine. Thus, a real need exists for computational methods capable of determining if Masking exists in medical alarm configurations before they are deployed. In this paper, we present such a method. Using a combination of formal modeling, psychoacoustic modeling, temporal logic specification, and model checking, our method is able to prove whether a modeled of a configuration of alarms can interact in ways that produce Masking. This paper provides the motivation for this method, presents its details, describes its implementation, demonstrates its power with a case study, and outlines future work.
Hidehiko Okamoto - One of the best experts on this subject based on the ideXlab platform.
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left hemispheric dominance during auditory processing in a noisy environment
BMC Biology, 2007Co-Authors: Hidehiko Okamoto, Henning Stracke, Bernhard Ross, Ryusuke Kakigi, Christo PantevAbstract:In daily life, we are exposed to different sound inputs Simultaneously. During neural encoding in the auditory pathway, neural activities elicited by these different sounds interact with each other. In the present study, we investigated neural interactions elicited by masker and amplitude-modulated test stimulus in primary and non-primary human auditory cortex during ipsi-lateral and contra-lateral Masking by means of magnetoencephalography (MEG). We observed significant decrements of auditory evoked responses and a significant inter-hemispheric difference for the N1m response during both ipsi- and contra-lateral Masking. The decrements of auditory evoked neural activities during Simultaneous Masking can be explained by neural interactions evoked by masker and test stimulus in peripheral and central auditory systems. The inter-hemispheric differences of N1m decrements during ipsi- and contra-lateral Masking reflect a basic hemispheric specialization contributing to the processing of complex auditory stimuli such as speech signals in noisy environments.
Christo Pantev - One of the best experts on this subject based on the ideXlab platform.
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left hemispheric dominance during auditory processing in a noisy environment
BMC Biology, 2007Co-Authors: Hidehiko Okamoto, Henning Stracke, Bernhard Ross, Ryusuke Kakigi, Christo PantevAbstract:In daily life, we are exposed to different sound inputs Simultaneously. During neural encoding in the auditory pathway, neural activities elicited by these different sounds interact with each other. In the present study, we investigated neural interactions elicited by masker and amplitude-modulated test stimulus in primary and non-primary human auditory cortex during ipsi-lateral and contra-lateral Masking by means of magnetoencephalography (MEG). We observed significant decrements of auditory evoked responses and a significant inter-hemispheric difference for the N1m response during both ipsi- and contra-lateral Masking. The decrements of auditory evoked neural activities during Simultaneous Masking can be explained by neural interactions evoked by masker and test stimulus in peripheral and central auditory systems. The inter-hemispheric differences of N1m decrements during ipsi- and contra-lateral Masking reflect a basic hemispheric specialization contributing to the processing of complex auditory stimuli such as speech signals in noisy environments.