Relative annoyance and loudness judgements of various simulated sonic boom waveforms

Effects of various simulated sonic boom waveforms on human subjective respons

Time-of-day Corrections to Aircraft Noise Metrics

The historical and background aspects of time-of-day corrections as well as the evidence supporting these corrections are discussed. Health, welfare, and economic impacts, needs a criteria, and government policy and regulation, are also reported

Relative effectiveness of several simulated jet engine noise spectral treatments in reducing annoyance in a TV-viewing situation

An experiment was conducted in order to determine the relative effectiveness of several hypothetical jet engine noise treatments and to test hypothesis that speech interference, at least in part, mediates annoyance in a TV-viewing situation. Twenty-four subjects watched television in a simulated living room. Recorded jet flyover noises were presented in such a way as to create the illusion that aircraft were actually flying overhead. There were 27 stimuli (nine spectra at three overall levels) presented at an average rate of approximately one flight every 2 minutes. Subjects judged the annoyance value of individual stimuli using either a category rating method or magnitude estimation method in each of two 1-hour sessions. The spectral treatments most effective in reducing annoyance were at 1.6 Khz and 800 Hz, in that order. The degree of annoyance reduction resulting from all treatments was affected by the overall sound level of the stimuli, with the greatest reduction at the intermediate overall sound level, about 88 to 89 db(A), peak value. The results are interpreted as supporting the hypothesis that speech interference, at least in part, mediates annoyance with aircraft noise in a TV-viewing situation

Sound attenuation apparatus

An apparatus is disclosed for reducing acoustic transmission from mechanical or acoustic sources by means of a double wall partition, within which an acoustic pressure field is generated by at least one secondary acoustic source. The secondary acoustic source is advantageously placed within the partition, around its edges, or it may be an integral part of a wall of the partition

Annoyance resulting from intrusion of aircraft sounds upon various activities

An experiment was conducted in which subjects were engaged in TV viewing, telephone listening, or reverie (no activity) for a 1/2-hour session. During the session, they were exposed to a series of recorded aircraft sounds at the rate of one flight every 2 minutes. Within each session, four levels of flyover noise, separated by dB increments, were presented several times in a Latin Square balanced sequence. The peak level of the noisiest flyover in any session was fixed at 95, 90, 85, 75, or 70 dBA. At the end of the test session, subjects recorded their responses to the aircraft sounds, using a bipolar scale which covered the range from very pleasant to extremely annoying. Responses to aircraft noises were found to be significantly affected by the particular activity in which the subjects were engaged. Not all subjects found the aircraft sounds to be annoying

Effects of three activities on annoyance responses to recorded flyovers

Human subjects participated in an experiment in which they were engaged in TV viewing, telephone listening, or reverie (no activity) for a 1/2-hour session. During the session, they were exposed to a series of recorded aircraft sounds at the rate of one flight every 2 minutes. At each session, four levels of flyover noise, separated by 5 db increments were presented several times in a Latin Square balanced sequence. The peak levels of the noisiest flyover in any session was fixed at 95, 90, 85, 75, or 70 db. At the end of the test session, subjects recorded their responses to the aircraft sounds, using a bipolar scale which covered the range from very pleasant to extremely annoying. Responses to aircraft noises are found to be significantly affected by the particular activity in which the subjects are engaged

Coupled Cluster Channels in the Homogeneous Electron Gas

We discuss diagrammatic modifications to the coupled cluster doubles (CCD) equations, wherein different groups of terms out of rings, ladders, crossed-rings and mosaics can be removed to form approximations to the coupled cluster method, of interest due to their similarity with various types of random phase approximations. The finite uniform electron gas is benchmarked for 14- and 54-electron systems at the complete basis set limit over a wide density range and performance of different flavours of CCD are determined. These results confirm that rings generally overcorrelate and ladders generally undercorrelate; mosaics-only CCD yields a result surprisingly close to CCD. We use a recently developed numerical analysis [J. J. Shepherd and A. Gr\"uneis, Phys. Rev. Lett. 110, 226401 (2013)] to study the behaviours of these methods in the thermodynamic limit. We determine that the mosaics, on forming the Brueckner Hamltonian, open a gap in the effective one-particle eigenvalues at the Fermi energy. Numerical evidence is presented which shows that methods based on this renormalisation have convergent energies in the thermodynamic limit including mosaic-only CCD, which is just a renormalised MP2. All other methods including only a single channel, namely ladder-only CCD, ring-only CCD and crossed-ring-only CCD, appear to yield divergent energies; incorporation of mosaic terms prevents this from happening.Comment: 9 pages, 4 figures, 1 table. Comments welcome: [email protected]

The incidence and risk factors for new onset atrial fibrillation in the PROSPER study

Aims Atrial fibrillation/flutter (AF) is the most common arrhythmia in older people. It associates with reduced exercise capacity, increased risk of stroke, and mortality. We aimed to determine retrospectively whether pravastatin reduces the incidence of AF and whether any electrocardiographic measures or clinical conditions might be risk factors for its development. Methods and results The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) was a randomized, double-blind controlled trial that recruited 5804 individuals aged 70-82 years with a history of, or risk factors for, vascular disease. A total of 2891 were allocated to pravastatin and 2913 to placebo; mean follow-up was 3.2 years. Electrocardiograms (ECGs), which were recorded at baseline, annually thereafter, and at run-out, were processed by computer and reviewed manually. In all, 264 of 2912 (9.1%) of the placebo group and 283 of 2888 (9.8%) of the pravastatin-treated group developed AF [hazard ratio 1.08 (0.92,1.28), P = 0.35)]. Multivariate analysis showed that PR and QTc intervals, age, left ventricular hypertrophy, and ST-T abnormalities were related to development of AF after adjustment for many variables including alcohol consumption, which itself was univariately predictive of developing AF. Previous myocardial infarction on the ECG was not a risk factor. A history of vascular disease was strongly linked with developing AF but not diabetes and hypertension. Conclusion Pravastatin does not reduce the incidence of AF in older people at risk of vascular disease, at least in the short-medium term. Risk factors for AF include older age, prolongation of PR or QTc intervals, left ventricular hypertrophy, and ST-T abnormalities on the EC

Broad band sound from wind turbine generators

Brief descriptions are given of the various types of large wind turbines and their sound characteristics. Candidate sources of broadband sound are identified and are rank ordered for a large upwind configuration wind turbine generator for which data are available. The rotor is noted to be the main source of broadband sound which arises from inflow turbulence and from the interactions of the turbulent boundary layer on the blade with its trailing edge. Sound is radiated about equally in all directions but the refraction effects of the wind produce an elongated contour pattern in the downwind direction

Torsion of a Wandering Spleen: Report of a Case

A CAJM article on causes of abdominal pain in an African girl in the rural Southern Rhodesia of the 1950's.The acute abdomen in the African is full of the unexpected, and any surgeon attacking the abdomen must be prepared for whatever he finds. This is especially difficult for the district government medical officers in the more isolated stations, where no ancillary services are at hand and no second opinion can be sought. The case reported here is one of torsion of a wandering spleen which was found lying in the right iliac fossa and pelvis adjacent to the uterus and right fallopian tube