An analytical expression for the relationship between the direct-to-reverberant energy ratio (DRR) and the coherence estimation function between coincident pressure and particle velocity component is derived. The analytical solution is first validated with simulated room impulse responses and then used to estimate the DRR in five octave bands for several receiver positions measured in a total of 11 rooms of vastly different sizes and acoustic characteristics. The accuracy is evaluated by comparison with the DRR estimated directly from the room impulse response. The difference is typically 5 dB. For two rooms, the variation of the DRR estimate with source-to-receiver position is also shown. The method is blind in the sense that it is virtually independent of the signal generated by a single sound source.

Sound propagation in enclosed spaces is characterized by reflections at the boundaries of the enclosure. Reflections can be wanted in the case when they support the direct sound or give a feeling of envelopment or they can be unwanted when they lead to echoes and colouration. When measuring multiple impulse responses in an enclosed space along an array the reflections can be mapped to the reflecting objects. Similar to seismic exploration, medical diagnostics, and underwater acoustics, an image of the reflecting objects is obtained in terms of reflected energy. The imaging process is based on inverse wave field extrapolation with the Kirchhoff–Helmholtz and Rayleigh integrals. The inverse of the imaging process recreates the measured impulse responses from the image and it allows one to remove or alter reflecting objects in the image and investigate their influence on the wave field in the enclosed space in a physically correct way. This can be verified by reimaging the altered wave field. Preliminary results from listening tests for the perceptual evaluation are presented. They indicate that the influence of a reflecting object can only be perceived in its close proximity.

Background: The effectiveness of worksite interventions to reduce smoking is debatable. Objectives: Acomprehensive smoking cessation intervention was implemented in a community of more than 17,000 employees at three different health care companies. The primary endpoint was abstinence at 24 months (self-reported and confirmed by exhaled carbon monoxide ≤6 parts per million). Predictors of long-term abstinence were analysed by multivariable regression analysis. Methods: The study was designed as an investigator-initiated and investigator-driven, open, multicentre, cohort study; 887 smokerswere enrolled in the programme. The intervention included intensive individual counselling as well as nicotine replacement and/or bupropion according to individual preferences. Re-interventions for relapse were offered during the 24-month follow-up. Results: The abstinence rate was 37% at 24 months and did not differ among the various medication groups (p > 0.05 for all). Predictors of successful cessation were higher age (odds ratio, OR 1.47, 95% confidence interval, CI 1.08-2.00, p < 0.01), breathlessness on exertion (OR 2.26, 95% CI 1.1-4.9, p = 0.03), and a higher educational level (OR 1.81, 95% CI 1.06-3.09, p = 0.03). Higher Fagerström (OR 0.76, 95% CI 0.59-0.97, p < 0.01) and craving scores (OR 0.75, 95% CI 0.63-0.89, p < 0.01), chronic sputum production (OR 0.52, 95% CI 0.31-0.87, p = 0.01) and use of antidepressants (OR 0.54, 95% CI 0.32-0.91, p = 0.02) were associated with ongoing smoking. Conclusion: Acomprehensive smoking cessation intervention at the workplace achieves high, stable, long-term abstinence rates. Elderly, well-educated employees with breathlessness on exertion have higher odds of quitting smoking. In contrast, those with high physical dependency and more intense craving, and those reporting use of antidepressant medication or sputum production have poorer chances to quit.

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Spatial correlation and coherence functions in reverberant sound fields are relevant to the acoustics of enclosed spaces and related areas. Theoretical expressions for the spatial correlation and coherence functions between signals representing the pressure and/or the components of the particle velocity vector in a reverberant sound field are established in the literature and most of these have also been corroborated with measurements [F. Jacobsen, J. Acoust. Soc. Am. 108, 204-210 (2000)]. In the present paper, these expressions are generalized to microphones of first-order directivity, whereby the directivity can be expressed in terms of pressure and pressure gradient. It is shown that the resulting spatial correlation and coherence functions can be expressed in terms of the established spatial correlation and coherence functions. The derived theoretical expression for the spatial coherence function is validated with a modeled diffuse sound field. Further, it is compared with the experimental coherence obtained from the reverberant tails of room impulse responses measured with two common surround sound microphone setups in a concert and a lecture hall.