Individual differences in the sensitivity to pitch direction

It is commonly assumed that one can always assign a direction-upward or downward-to a percept of pitch change. The present study shows that this is true for some, but not all, listeners. Frequency difference limens (FDLs, in cents) for pure tones roved in frequency were measured in two conditions. In one condition, the task was to detect frequency changes; in the other condition, the task was to identify the direction of frequency changes. For three listeners, the identification FDL was about 1.5 times smaller than the detection FDL, as predicted (counterintuitively) by signal detection theory under the assumption that performance in the two conditions was limited by one and the same internal noise. For three other listeners, however, the identification FDL was much larger than the detection FDL. The latter listeners had relatively high detection FDLs. They had no difficulty in identifying the direction of just-detectable changes in intensity, or in the frequency of amplitude modulation. Their difficulty in perceiving the direction of small frequency/pitch changes showed up not only when the task required absolute judgments of direction, but also when the directions of two successive frequency changes had to be judged as identical or different.     

Disturbance of sleep by noise: Individual differences

The literature on the effects of noise on sleep is searched for evidence on individual differences along the dimensions of age, sex, occupation, personality, neuroticism, and mental health. With the exception of age, little firm evidence is found. Thus there remains a need to establish at better than the anecdotal level whether or not real individual differences exist.     

Individual differences in noise annoyance and the uncomfortable loudness level

Uncomfortable loudness levels were measured for two groups of subjects with either high or low scores on a noise annoyance questionnaire. The study was conducted in two stages. In the first stage scores of noise annoyance, general annoyance and locus of control were obtained from 122 respondents. Two groups of responders on the noise annoyance questionnaire attended the laboratory for the second stage involving a determination of the uncomfortable loudness level (ULL) by two methods (Békésy and analogue adjustment) and for two types of sound source (white noise and a 1 kHz tone). The key findings from the first stage were that (i) noise annoyance scores were not bimodal, showing no significant deviation from normality, (ii) females showed higher noise annoyance and (iii) both general annoyance and locus of control scales showed significant positive correlations with noise annoyance. Findings from the second stage showed that (i) Békésy determinations gave higher ULL's than those from the analogue adjustment method, (ii) based on annoyance scores, noise-annoyed subjects produced significantly higher ULL's than their less annoyed counterparts but only with the analogue determination with a 1 kHz tone, (iii) females produced markedly lower ULL's than males and (iv) deactivation, locus of control and extroversion were identified as mediating factors in the setting of the ULL. The results were further discussed in terms of methodological differences between this and earlier studies.     

An exploratory study into the prediction of low frequency traffic noise

An exploratory study whose main aim was to develop equations for the prediction of low frequency traffic noise scales (from traffic parameters) is described. Summaries of noise and traffic measurement procedures are documented and the results of data analysis presented.The equations developed are shown to be accurate, but will require development to cater for more variable site conditions. The equations also indicate the large contribution made to low frequency noise levels by heavy vehicles. The implication of this for ‘lorry nuisance’ is discussed. Broad-band scales are shown to be reasonable surrogates for most, but not all, narrow-band low frequency effects. A method for determining low frequency scales using simple instrumentation is described.This paper is the first of three based on work carried out with the assistance of the Greater London Council (Scientific Branch) and which deal with the prediction of low frequency traffic noise scales and their relevance to vibration disturbance, lorry nuisance and building vibration.     

A Dutch study on railroad traffic noise

This paper is about a Dutch study on the community response to noise. The set-up of the study is described broadly. Some details are given about the comprehensive sound level measurement programme. Some preliminary results from the social survey are given. A major finding is that annoyance is caused less by the sound of trains running through than by other sounds from the track.     

An empirical model for the noise propagation in open cast mines - A case study

Data obtained from 312 measurement stations of sound propagation in panel 48 of the Tuncbilek open cast mine, Western Lignite Corporation, Turkey have been used to create an empirical model for such propagation. As well as the noise level recorded at these stations, atmospheric conditions were recorded also by the meteorological station located at the same panel. A total of 95,000 noise values were recorded at these stations. In addition the distances of the measurement stations to the effective source of noise and to the working slope, the meteorological effects and the number of noise sources were defined for each of 312 measurement stations. Using these data, the proposed model was tested against the noise measurements.     

Responses to an increase in road traffic noise

Results are presented of a small longitudinal study of community response to road traffic noise following an increase in traffic along a residential street. A total of 20 respondents were surveyed and they showed no evidence of adaptation to the increased noise over the period between 7 and 19 months after the increase in traffic. Respondents' assessments of annoyance with the before-change conditions, made retrospectively after the change, were quite different from the assessments of annoyance that they made before the change occurred, though most of this difference was contributed by 8 of the 20 respondents. This small data set, when put together with other evidence on response to changed conditions, suggests that response bias is present in steady state assessments of annoyance and of a magnitude which would significantly affect the validity of self-reports of annoyance.     

A categorization method applied to the study of urban road traffic noise

The present work summarizes a study of the hypothesis that urban noise can be stratified by measuring street noise according to a prior classification of a town's streets according to their use in communicating the different zones of the town. The method was applied to five medium-sized Spanish towns (Vitoria-Gasteiz, Salamanca, Badajoz, Cáceres, and Mérida) with populations ranging from 218 000 down to 50000 and with different socio-economic characteristics, climate, etc. As the initial hypothesis of the work was that traffic is the main source of urban noise and is also the principal cause of the variability of the sound levels measured in urban settings, the study focused only on the five nonpedestrian categories of streets. The continuous equivalent sound level (Leq) was employed in the statistical analysis as it is commonly used as a general noise index, and other noise indicators such as L(DN) or L(DEN) are calculated from it. It was found that, although differences between the medians were not statistically significant in some of the towns for certain pairs of adjacent categories, the differences between pairs of nonadjacent categories were always significant, indicative of the stratification of noise in these five towns. Further studies on other medium-sized towns and on large towns and small villages would be needed to test whether the present definition of street categories is extensible elsewhere without modification.     

Predicting community response to road traffic noise

Several problems related to identifying the potential future impacts of road traffic noise on residential areas require for their solution the ability to predict subjective response to road traffic noise. The main difficulty in using existing regression equations relating subjective response and traffic noise for such predictions is that there has been no reported test of whether or not the data used meet the assumptions of the regression model. If the assumptions are not met, the replicability of the results and hence the reliability of the predictions, as measured by confidence limits or standard errors, cannot be established, because such inference rests on the statistical assumptions. Investigation of the data collected in a traffic noise impact study in southern Ontario indicates that such data meet the assumptions necessary for inference from regression analysis. Consequently, valid estimates of the reliability of predictive equations derived from regression analysis can be made using the standard errors of the regression parameters. This stronger inferential base also permits comparisons among different noise measures oramong different response measures. It appears that several noise measures (L_eq, L₁₀, L_dn) are all equally good predictors of subjective response. It also appears that different indicators of subjective response yield significantly different regression parameters.     

An empirical study of common traffic congestion features based on traffic data measured in the USA,the UK,and Germany

Based on real traffic data measured on American, UK and German freeways, we study common features of traffic congestion. We have found that traffic features [J] and [S] defining traffic phases “wide moving jam” (J) and “synchronized flow” (S) in Kerner’s three-phase theory are indeed common spatiotemporal traffic features observed in the UK, the USA and Germany. For the testing of Kerner’s “line J”, representing the propagation of the wide moving jam’s downstream front, four different methods for a study of moving jam propagation in empirical data are studied and compared for each congested traffic situation occurring in the three countries. A statistical study of velocities of wide moving jam fronts is presented, which has been performed through the analysis of database containing more than 280.000 min of observed wide moving jams measured on about 1200 km long freeway network in Hessen (Germany) during more than two years.     

Parametric study of EEG sensitivity to phase noise during face processing

Background

The zitter (zi/zi) rat, a loss-of-function mutant of the glycosylated transmembrane protein attractin (atrn), exhibits widespread age-dependent spongiform degeneration, hypomyelination, and abnormal metabolism of reactive oxygen species (ROS) in the brain. To date, the mechanisms underlying these phenotypes have remained unclear.

Results

Here, we show differentiation defects in zi/zi oligodendrocytes, accompanied by aberrant extension of cell-processes and hypomyelination. Axonal bundles were relatively preserved during postnatal development. With increasing in age, the injured oligodendrocytes in zi/zi rats become pathological, as evidenced by the accumulation of iron in their cell bodies. Immunohistochemical analysis revealed that atrn expression was absent from an oligodendrocyte lineage, including A2B5-positive progenitors and CNPase-positive differentiated cells. The number and distribution of Olig2-positive oligodendrocyte progenitors was unchanged in the zi/zi brain. Furthermore, an in vitro differentiation assay of cultured oligodendrocyte progenitors prepared from zi/zi brains revealed their normal competence for proliferation and differentiation into mature oligodendrocytes. Interestingly, we demonstrated the accelerated recruitment of ED1-positive macrophages/microglia to the developing zi/zi brain parenchyma prior to the onset of hypomyelination. Semiquantitative RT-PCR analysis revealed a significant up-regulation of CD26 and IL1-β in the zi/zi brain during this early postnatal stage.

Conclusion

We demonstrated that the onset of the impairment of oligodendrocyte differentiation occurs in a non-cell autonomous manner in zi/zi rats. Hypomyelination of oligodendrocytes was not due to a failure of the intrinsic program of oligodendrocytes, but rather, was caused by extrinsic factors that interrupt oligodendrocyte development. It is likely that macrophage/microglial activation in the zi/zi CNS leads to disturbances in oligodendrocyte differentiation via deleterious extrinsic factors, such as the cytokine IL1-β or ROS. Atrn might be involved in the activation of brain macrophages/microglia by suppressing excessive migration of monocytes into the CNS, or by accelerating the transformation of brain monocytes into resting microglia. Understanding the pathogenesis of the zi/zi rat may provide novel insights into the developmental interaction betweens macrophages/microglia and cells of an oligodendrocyte lineage.     

Vertical distribution of traffic noise—A preliminary study

This paper examines the effect of flight on the sound radiated by a high frequency source embedded in a constant area jet pipe in the presence of flow. Ray acoustics theory and classical results for sound transmission at an interface of relative motion are used. The diffraction of sound at the nozzle lips, the inhomogeneity and irregularity of the interface and the possibility of instability waves being triggered by the incident sound are neglected. Some of the waves characterized by wave-fronts pointing upstream are shown to be convected downstream by the flow and to illuminate the forward arc after refraction at the jet interface. The amount of energy emitted by the source, which is trapped inside the flow, depends only on internal jet pipe conditions. However, the portion of the forward arc which is illuminated by this energy, is a function of flight speed. The radiation into the ambient atmosphere at rest of a basically omnidirectional source peaks at the edge of the downstream zone of silence and falls off rapidly when the observation angle is increased. The flight to static comparison reveals an interesting forward arc amplification due to flight but this occurs in a range of angles where the radiation is basically rather feeble.     

Honking noise corrections for traffic noise prediction models in heterogeneous traffic conditions like India

In developing countries like India, the nature of the composition of traffic is heterogeneous. A heterogeneous traffic flow consists of vehicles that have different sizes, speeds, vehicle spacing and operating characteristics. As a result of the widely varying speeds, vehicular dimensions, lack of lane disciplines, honking becomes inevitable. In addition, it changes the urban soundscape of developing countries. In heterogeneous traffic conditions, horn events increase noise level (L_den) by 0.5–13 dB(A) as compared to homogenous traffic conditions. Therefore, the traffic prediction models that are used for homogenous traffic conditions are not applicable in heterogeneous traffic conditions. To increase the accuracy of noise prediction models, in depth understanding of heterogeneous traffic noise is required. Understanding the real traffic noise characteristics requires quantification of some of the basic traffic flow characteristics such as speed, flow, Level Of Service (LOS) and density. In a given roadway, the noise level changes with density and LOS on the road. In this paper, a new factor for horn correction is introduced with respect of Level Of Service (LOS). The horn correction values can be incorporated in traffic noise models such as CRTN, FHWA, and RLS 90, while evaluating heterogeneous traffic conditions.     

Community reactions to noise from freely flowing traffic,motorway traffic and congested traffic flow

Responses to a social survey were collected from residents of 27 different sites in the Greater Manchester area. The sites were exposed to noise emanating from (a) freely flowing traffic on urban roads, or (b) motorway traffic, or (c) congested or disturbed traffic flow on urban roads. Existing noise indices were tested on this general sample of traffic flow situations to determine their efficacy in the prediction of community dissatisfaction to traffic noise. No existing index could handle adequately all the traffic flow conditions. When the indices were combined with measures of traffic volume flow between midnight and 6 a.m. a marked improvement in their predictive capability was noted. In particular, extended indices based on L₁₀ (18 hour) and L_eq appeared to be useful predictors of community response to all of the traffic flow situations studied in this project.     

Long term sleep disturbance due to traffic noise

This contribution to the evaluation of the effects of traffic noise on sleep disturbance is focused on the responses of people living near a main road. Experiments were carried out in the homes of subjects who had habitually been exposed to noise for periods of more than four years. The chronic changes in overall sleep patterns and the temporary sleep responses to particular noise events caused by traffic are demonstrated. Young people show mainly stage 3 and 4 deficits whilst older people show REM sleep deficits. The cardiac response to noise during sleep was also examined. These results highlight that both long term average and peak levels are important in assessing sleep disturbance. The threshold levels, measured inside the bedroom and above which sleep quality starts to become impaired, are 37 L_eq(A) and 45 dB (A)L_{p max}, respectively. For the type of traffic studied these two levels are coherent and it is therefore possible that a single noise index, L_eq(A), is sufficient to scale sleep disturbance.