Evidence for proactive and retroactive temporal pattern analysis in simultaneous maskinga).

Amplitude modulation (AM) of a masker reduces its masking on a simultaneously presented unmodulated pure-tone target, which likely involves dip listening. This study tested the idea that dip-listening efficiency may depend on stimulus context, i.e., the match in AM peakedness (AMP) between the masker and a precursor or postcursor stimulus, assuming a form of temporal pattern analysis process. Masked thresholds were measured in normal-hearing listeners using Schroeder-phase harmonic complexes as maskers and precursors or postcursors. Experiment 1 showed threshold elevation (i.e., interference) when a flat cursor preceded or followed a peaked masker, suggesting proactive and retroactive temporal pattern analysis. Threshold decline (facilitation) was observed when the masker AMP was matched to the precursor, irrespective of stimulus AMP, suggesting only proactive processing. Subsequent experiments showed that both interference and facilitation (1) remained robust when a temporal gap was inserted between masker and cursor, (2) disappeared when an F0-difference was introduced between masker and precursor, and (3) decreased when the presentation level was reduced. These results suggest an important role of envelope regularity in dip listening, especially when masker and cursor are F0-matched and, therefore, form one perceptual stream. The reported effects seem to represent a time-domain variant of comodulation masking release.

Temporal integration contributes to the masking release by amplitude modulation.

Modulated maskers produce less amount of masking than unmodulated maskers, an effect referred to as masking release (MR). Both listening in the temporal dips and fast cochlear compression have been suggested as underlying mechanisms. We addressed the role of dip listening by measuring temporal integration in simultaneous masking using Schroeder-phase harmonic complexes (SPHC) with various phase curvatures. In an experiment with six normal-hearing listeners, SPHC masker and pure-tone target stimuli were covaried in duration at a high masker level. The MR increased with stimulus duration, suggesting integration of target information across multiple masker dips. The duration dependence of the MR was predicted by a physiology-inspired model based on the temporal envelope modulation strength in the auditory periphery. The modeling analysis suggested that listeners detect the presence of the target by a reduction in fluctuation strength that results primarily from a decline of F0-based response peaks, an effect known as synchrony capture. The detailed pattern of masked thresholds across various masker phase curvatures was not predicted by the model, suggesting that its phase response does not well fit the human phase response. Overall, temporal integration across neural envelope features associated with the masker dips seems to contribute to the MR with SPHCs.

Implementation of a health education program in Asia, comparing Thailand, Indonesia, and Japan.

BACKGROUND: The global community is faced with aging societies, which will result in increased health care costs. we have been introducing our International Organization for Standardization (ISO)-certified health education system in Thailand and Indonesia. OBJECTIVE: The purpose of this study was to collect data on the effects of this ISO-certified health education system, to extend the healthy life expectancy and to study the feasibility of implementing this program and in new social contexts. METHODS: We implemented the health education program recruiting 43, 114 and 119 participants, respectively, in Japan, Thailand and Indonesia. The participants' conditions before and after the program were determined through anthropometry, physical fitness tests, blood chemistry tests, brain function tests and pedometry. RESULTS: Regarding pedometry, the Japanese participants took the highest number of daily steps on average, followed by the Indonesian and Thai participants. In the 10-m obstacle walk, the Thai and Indonesian participants had significantly increased times. Furthermore, the differentiation reaction time, reverse differentiation reaction time, total number of "misses", total number of "mistakes" and total number of errors significantly improved. CONCLUSION: It is possible to implement a program of an ISO-certified health education system, but how to develop exercise habits is important.

The effectiveness of a Japanese style health program: comparison between Minowa, Japan and Rayong, Thailand.

AIM: This study aimed to appropriately establish a Japanese style healthcare program under the ISO9001:2008 (ISO: International Organization for Standardization) in Minowa, Japan and Rayong, Thailand to improve problem areas and inspect its effectiveness. Furthermore, we want to make this health promotion through ISO widely available in Asian countries and to make an international contribution. METHOD: We implemented a 6-month health program in the c Rayong city, Thailand, and a 12 month health program in the Minowa town, Japan. This study assessed findings from pedometry, anthropometry and blood pressure measurements, physical fitness, blood chemistry, and brain function tests. RESULTS: The comparisons were made using interaction effects between the participants in Rayong and Minowa. They showed significant differences in the 10-m obstacle walk, the 6-minute walk, HDL, the reverse and reverse differentiation time, the total number of forgets, the total number of mistakes, and the total number of brain function errors. CONCLUSIONS: To improve the brain function in participants from Rayong through this health education program, measures such as increasing the number of steps, adding muscular strength/stretching exercises, and home training every day is suggested.

Psychophysical and modeling approaches towards determining the cochlear phase response based on interaural time differences.

The cochlear phase response is often estimated by measuring masking of a tonal target by harmonic complexes with various phase curvatures. Maskers yielding most modulated internal envelope representations after passing the cochlear filter are thought to produce minimum masking, with fast-acting cochlear compression as the main contributor to that effect. Thus, in hearing-impaired (HI) listeners, reduced cochlear compression hampers estimation of the phase response using the masking method. This study proposes an alternative approach, based on the effect of the envelope modulation strength on the sensitivity to interaural time differences (ITDs). To evaluate the general approach, ITD thresholds were measured in seven normal-hearing listeners using 300-ms Schroeder-phase harmonic complexes with nine different phase curvatures. ITD thresholds tended to be lowest for phase curvatures roughly similar to those previously shown to produce minimum masking. However, an unexpected ITD threshold peak was consistently observed for a particular negative phase curvature. An auditory-nerve based ITD model predicted the general pattern of ITD thresholds except for the threshold peak, as well as published envelope ITD data. Model predictions simulating outer hair cell loss support the feasibility of the ITD-based approach to estimate the phase response in HI listeners.

The role of compression in the simultaneous masker phase effect.

Peripheral compression is believed to play a major role in the masker phase effect (MPE). While compression is almost instantaneous, activation of the efferent system reduces compression in a temporally evolving manner. To study the role of efferent-controlled compression in the MPE, in experiment 1, simultaneous masking of a 30-ms 4-kHz tone by 40-ms Schroeder-phase harmonic complexes was measured with on- and off-frequency precursors as a function of masker phase curvature for two masker levels (60 and 90 dB sound pressure level). The MPE was quantified by the threshold range [min/max difference (MMD)] across the phase curvatures. For the 60-dB condition, the presence of on-frequency precursor decreased the MMD from 10 to 5 dB. Experiment 2 studied the role of the precursor on the auditory filter's bandwidth. The on-frequency precursor was found to increase the bandwidth, an effect incorporated in the subsequent modeling. A model of the auditory periphery including cochlear filtering and basilar membrane compression generally underestimated the MMDs. A model based on two-step compression, including compression of inner hair cells, accounted for the MMDs across precursor and level conditions. Overall, the observed precursor effects and the model predictions suggest an important role of compression in the simultaneous MPE.

Comparative survey of go/no-go results to identify the inhibitory control ability change of Japanese children.

This research, conducted in 1998 and 2008, uses go/no-go data to investigate the fundamentals of cognitive functioning in the inhibitory control ability of Japanese children. 844 subjects from kindergarten to junior high school participated in go/no-go task experiments. Performance of go/no-go tasks, which are frequently used to investigate response inhibition, measures a variety of cognitive components besides response inhibition. With normal brain development, the ability to inhibit responses improves substantially in adolescence. An increase over time in the error rate during the go/no-go tasks of subjects of the same age indicates that these processes are not functioning properly. Comparisons between the 1998 and 2008 data revealed several differences in error rates. In 2008, there were increases in the number of errors in groups from each age range. The comparison also revealed that overall error rates peaked at later ages in the 2008 subjects. Taken together, these results show changing conditions in the inhibitory function of the prefrontal cortex. However, the reason for these changing conditions remains unclear. While a lifestyle questionnaire revealed several differences in factors such as bedtimes and hours spent watching TV, analysis did not reveal a significant correlation.

Effects of randomizing phase on the discrimination between amplitude-modulated and quasi-frequency-modulated tones.

This study investigated the bandwidth of phase sensitivity. Subjects discriminated amplitude-modulated tones (AM), and quasi-frequency-modulated tones (QFM) in a two-interval, forced-choice task. An adaptive threshold procedure was used to estimate the modulation depth needed to discriminate the stimuli as a function of carrier and modulation frequency. Non-monotonicities in threshold-bandwidth functions were often observed at higher modulation frequencies. The results are discussed in terms of two potential cues: (1) waveform envelope, (2) cubic distortion products. In order to degrade the information obtained from auditory distortions, the phase for the carrier frequency was randomly sampled from a uniform distribution, which diminished the non-monotonicities with minimal effect at lower modulation frequencies. Model simulations demonstrated that phase randomization degrades distortion product cues with only a modest effect on temporal cues. Final results show that maximum bandwidths for phase sensitivity (BW(max)) were not proportional to carrier frequencies.