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Theoretical considerations and experimental evidence suggest that otoacoustic emission parameters may be used to reveal early cochlear damage, even before it can be diagnosed by standard audiometric techniques. In this work, the statistical distributions of a set of otoacoustic emission parameters chosen as candidates for the early detection of cochlear damage (global and band reproducibility, response level, signal-to-noise ratio, spectral latency, and long-lasting otoacoustic emission presence) were analyzed in a population of 138 ears. These ears have been divided, according to a standard audiometric test, in three classes: (1) ears of nonexposed bilaterally normal subjects, (2) normal ears of subjects with unilateral noise-induced high-frequency hearing loss, and (3) their hearing impaired ears. For all analyzed parameters, a statistically significant difference was found between classes 1 and 2. This difference largely exceeds the difference observed between classes 2 and 3. This fact suggests that the noise exposure, which was responsible for the unilateral hearing loss, also caused subclinical damage in the contralateral, audiometrically normal, ear. This is a clear indication that otoacoustic emission techniques may be able to early detect subclinical damages.

The purpose of this study was to assess differences in sound spectra of crying of term newborns in relation to different pain levels. Fifty-seven consecutively born neonates were evaluated during heel-prick performed with different analgesic techniques.Crying was recorded and frequency spectrograms analyzed. A pain score on the DAN (Douleur Aiguë du Nouveau-né) scale was assigned to each baby after the sampling. Three features were considered and correlated with the corresponding DAN scores: 1) whole spectral form; 2) the fundamental frequency of the first cry emitted (F 0 ); and 3) root mean square sound pressure normalized to its maximum. After emission of the first cry, babies with DAN scores Ͼ8, but not with DAN scores Յ8 (p Ͻ 0.001), showed a pattern ("siren cry") characterized by a sequence of almost identical cries with a period on the order of 1 s. A statistically significant correlation was found between root mean square (r 2 ϭ 89%, p Ͻ 0.01), F 0 (r 2 ϭ 32%, p Ͻ 0.05), siren cry (r 2 ϭ 68.2%, p ϭ 0.02), and DAN score. F 0 did not show significant correlation with DAN score in the subset of neonates with DAN scores Յ8 (r 2 ϭ 1.4%, p ϭ 0.94), and babies with a DAN score Ͼ8 had a significantly higher F 0 than those with lower DAN scores (p ϭ 0.016). An alarm threshold exists between high (Ͼ8) and low (Յ8) DAN scores: crying has different features in these two groups. When pain exceeds a DAN score of 8, usually a first cry at a high pitch is emitted, followed by the siren cry, with a sound level maintained near its maximum. Crying is simultaneously a sign, symptom, and signal (1). It is the infant's earliest form of communication, but the significance and meaning of neonatal crying are still unclear (2) because different crying features do not reflect different causes (e.g. hunger, pain, and fussiness) (3), but different degrees of distress (4 -6), so that gradations of crying may help a listener to narrow down the range of possible causes, but only with the help of contextual information (4, 6 -9). In the last few years, pain scales have been developed to discriminate levels of pain suffered by newborns (10 -15), but when analyzing crying, the level of the pain that provoked it is rarely considered (16). The aim of this study was to investigate to what extent crying features vary with the level of pain. To achieve this goal, we studied cry frequency spectrograms at different pain levels expressed by a validated pain scale. METHODS SubjectsThis report is based on analysis of a cohort of 57 newborns extrapolated from a previous study (17) consisting of 120 healthy term infants who underwent heel-prick for neonatal screening. Inclusion criteria were Apgar score at least 9 at 5 min, gestational age 38 -41 wk, age more than 48 h, and more than 2 h since last meal. During heel-prick, different analgesic procedures were used, namely SS, SS without oral sugar, oral sugar, sucking, and oral sugar plus sucking. These analgesic procedures were chosen to assess whether SS, a multisensorial stimulation consisting of m...

The input/output functions of the different-latency components of human transient-evoked and stimulus-frequency otoacoustic emissions are analyzed, with the goal of relating them to the underlying nonlinear dynamical properties of the basilar membrane response. Several cochlear models predict a cubic nonlinearity that would yield a correspondent compressive response. The otoacoustic response comes from different generation mechanisms, each characterized by a particular relation between local basilar membrane displacement and otoacoustic level. For the same mechanism (e.g., reflection from cochlear roughness), different generation places would imply differently compressive regimes of the local basilar membrane dynamics. Therefore, this kind of study requires disentangling these contributions, using suitable data acquisition and time-frequency analysis techniques. Fortunately, different generation mechanisms/places also imply different phase-gradient delays, knowledge of which can be used to perform this task. In this study, the different-latency otoacoustic components systematically show differently compressive response, consistent with two simple hypotheses: (1) all emissions come from the reflection mechanism and (2) the basilar membrane response is strongly compressive in the resonance region and closer to linear in more basal regions. It is not clear if such a compressive behavior also extends to arbitrarily low stimulus levels.

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A nonlinear and non-local cochlear model has been efficiently solved in the time domain numerically, obtaining the evolution of the transverse displacement of the basilar membrane at each cochlear place. This information allows one to follow the forward and backward propagation of the traveling wave along the basilar membrane, and to evaluate the otoacoustic response from the time evolution of the stapes displacement. The phase/frequency relation of the response can be predicted, as well as the physical delay associated with the response onset time, to evaluate the relation between different cochlear characteristic times as a function of the stimulus level and of the physical parameters of the model. For a nonlinear cochlea, simplistic frequency-domain interpretations of the otoacoustic response phase behavior may give inconsistent results. Time-domain numerical solutions of the underlying nonlinear and non-local full cochlear model using a large number (thousands) of partitions in space and an adaptive mesh in time are rather time and memory consuming. Therefore, in order to be able to use standard personal computers for simulations reliably, the discretized model has been carefully designed to enforce sparsity of the matrices using a multi-iterative approach. Preliminary results concerning the cochlear characteristic delays are also presented.

A study to quantify the UV exposure of vineyard workers was carried out using polysulphone dosimetry. The study took place in Tuscany (Italy) involving 32 vineyard workers, covering three different stages of the vine's growth. The level of personal exposure expressed as a function on the available ambient UV radiation was determined. We also assessed skin reflectance parameters, pre and post exposure. It was found that during spring backs received between 53% and 87% of ambient exposure and arms between 30% and 60%. During summer, the workers received on the back between 36% and 77% of ambient exposure and between 19% and 43% of ambient exposure on the arm. The comparison with the occupational UV exposure limit showed that all subjects received UV exposures in excess of the limit. The exposure of back of neck exceeded 10 SED (assumed as a threshold level of sun-adapted skin for Mediterranean subjects) in spring, which means that in the case of non sun-adapted skin and without sun protection, erythema can be induced in this targeted population. The cumulative exposure was also estimated under specific assumptions of UV exposure giving values in some cases higher than previous studies.