Acoustic pulse reflectometry is a relatively recent technique which allows the non-invasive measurement of human airways. The technique consists of guiding an acoustic impulse through the subject's mouth and into the airway. Suitable analysis of the resulting reflection (the 'echo') allows a reconstruction of the area-distance function. The non-invasive nature of the technique offers significant advantages over the established methods of x-ray cephalometry and CT scanning, and makes it very attractive for the investigation of ENT problems and sleep apnoea, and in the anaesthetic management of patients. This paper describes the theory and limitations of acoustic reflectometry, discusses previous work, and suggests some modifications: it is currently being implemented clinically.
They wept like anything to seeSuch quantities of sand.“If this were only cleared away,”They said, “it would be grand.”It would be, and if those young airmen of whom we heard in the February Gazette had not spent so much lost endeavour in weaving ropes of this sand, perhaps they would not now be in such need of the help which we are so eager to give them. For although the seven-times-seven mops of our teaching committees have been sweeping for far more than half a year, there is no doubt that school Arithmetic is still cumbered with a lot of stuff that is of no use outside the class-room. In spite of the fact that teachers mostly teach so well, and pupils learn so well, we must confess that children going out into the world often cannot do the calculations that they need, that Training College lecturers find that many students have to learn Arithmetic all over again (though we camouflage it as “Method”), and that intelligent well-educated folk seem to delight in telling anyone whom they suspect of mathematical leanings that “they never could do Arithmetic”. Surely it is the Arithmetic that is wrong, not the teachers or taught.
A LEED-Gold certified government building includes six floors of open-plan office space that are equipped with electronic sound masking delivered from a raised floor having under-floor air distribution (UFAD). Results of user polling show mixed results for acoustic satisfaction, with significant complaints about speech privacy, and noise from the systems interfering with users’ ability to work. This research focuses on this dissatisfaction, the general conflict between speech privacy ease of verbal communication, and acceptance of noise-generating treatments. Little research has been done on masking delivered via UFAD, so it was also desired to further the understanding of this design as part of a larger research program by the Federal government on Green Buildings. Specific objectives were to develop and test possible remedies for this system, and improve planning of future facilities that may have masking via UFAD. On-site measurements of masking and HVAC spectra, as well as noise reduction and observations for various conditions, were made. Post-measurement data analysis was conducted, and experimental remedies were developed and tested. The results and recommendations will be presented.
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