Supra-Segmental Changes in Speech Production as a Result of Spectral Feedback Degradation: Comparison with Lombard Speech

Perturbations to acoustic speech feedback have been typically localized to specific phonetic characteristics, for example, fundamental frequency (F0) or the first two formants (F1/F2), or affect all aspects of the speech signal equally, for example, via the addition of background noise. This paper examines the consequences of a more selective global perturbation: real-time cochlear implant (CI) simulation of acoustic speech feedback. Specifically, we examine the potential similarity between speakers’ response to noise vocoding and the characteristics of Lombard speech. An acoustic analysis of supra-segmental characteristics in speaking rate, F0 production, and voice amplitude revealed changes that paralleled the Lombard effect in some domains but not others. Two studies of speech intelligibility complemented the acoustic analysis, finding that intelligibility significantly decreased as a result of CI simulation of speaker feedback. Together, the results point to differences in speakers’ responses to these two superficially similar feedback manipulations. In both cases we see a complex, multi-faceted behavior on the part of talkers. We argue that more instances of global perturbation and broader response assessment are needed to determine whether such complexity is present in other feedback manipulations or if it represents a relatively rare exception to the typical compensatory feedback response.

Analysis of enamel surface damage after selective laser ablation of composite from tooth surfaces

Resin-based composites are used for many applications in dentistry. They are difficult to remove without damage to the underlying enamel since they adhere strongly and are color matched to the tooth. The objective of this study was to determine if an automated laser scanning system with spectral feedback could be used for selective removal of residual orthodontic composite from tooth surfaces with minimal damage to the underlying enamel.A COThe amount of enamel lost averaged between 20 and 25 μm for irradiation intensities from 3.8 to 4.2 J/cmResidual composite can be rapidly removed from tooth surfaces using a CO

THE LINEAR DEPENDENCE AND FEEDBACK SPECTRA BETWEEN STOCK MARKET AND ECONOMY

Geweke studied the measure of linear dependence and spectral feedback for grouped multivariate time series. This paper applies the measure of linear dependence and spectral feedback to examining the relationship between grouped variables of economy and stock market indices. Putting economic variables into one group and stock market variables into another, we examine the between-group relationship within the US, within Japan, and within the European Union. Using a self-developed computing program, the feedback spectra for grouped variables are calculated and displayed. Although risk might exist in that the significance levels for test may not be reliable because the feedback spectra are measured on possibly nonstationary variables in level, the patterns of the feedback spectra still provide information about the cyclical effect between the variable groups.