The Quantification of Strike Pitch and Pitch Shifts in Church Bells

The primary objective of the work reported in this thesis was to quantify how the pitch or strike note of a bell is determined by the frequencies of its partials. Pitches of bells are generally virtual pitch or missing fundamental effects, generated in the ear rather than present as a frequency in the radiated sound. The exact pitch is shifted from that expected for the missing fundamental by changes in the frequency of various partials. This can cause bells whose partials are in theory tuned precisely, to sound out of tune by considerable fractions of a semitone. The pitch shifts were quantified at frequencies across the audible spectrum by a set of experiments carried out on 30 subjects. Subsidiary experiments established which partials create a bell’s pitch or pitches at different frequencies, and showed that partial amplitude does not significantly affect bell pitch. A simple model of pitch shift was devised from the test results which gave good agreement with the stretch tuning in a number of peals of bells. Stretch tuning has not previously been satisfactorily explained. The pitch shifts were also compared against Terhardt’s algorithm for virtual pitch, which did not predict the shifts seen in practice. To prepare for these experiments, a comprehensive investigation was done of the partial frequencies of over 2,000 bells with a wide range of dates, weights and founders. An unexpected and straightforward relationship was found between the frequencies of the upper partials which generate virtual pitches, which seems to apply to all bronze and steel bells of Western shape. The relative frequencies of these partials are in turn determined by the thickness of the bell’s wall near the rim. This relationship between the partials has not been previously reported, and explains previous failed attempts by bellfounders to tune these partials independently. The modified version of Chladni’s law proposed by Perrin and Rossing for these partial frequencies was found not to give as good a fit to their frequencies as the relationship discovered in this research. The work presented in this thesis is important for at least two reasons: • It provides new practical guidance for the design and tuning of bells • The shifts in virtual pitches observed as a result of upper partial changes support current research into pitch generation mechanisms in the human ear

Virtual Pitch and Pitch Shifts in Church Bells

It is well established that musical sounds comprising multiple partials with frequencies approximately in the ratio of small integers give rise to a strong sensation of pitch even if the lowest or fundamental partial is missing—the so-called virtual pitch effect. Experiments on thirty test subjects demonstrate that this virtual pitch is shifted significantly by changes in the spacing of the constituent partials. The experiments measured pitch by comparison of sounds of similar timbre and were automated so that they could be performed remotely across the Internet. Analysis of the test sounds used shows that the pitch shifts are not predicted by Terhardt’s classic model of virtual pitch. The test sounds used were modelled on the sounds of church bells, but a further experiment on seventeen test subjects showed that changes in partial amplitude only had a minor effect on the pitch shifts observed, and that a pitch shift was still observed when two of the lowest frequency partials were removed, so that the effects reported are of general interest

Partial frequencies and Chladni’s law in church bells

The rim partials of a church bell (those with an antinode at the soundbow) generate the strike pitch or perceived note of the bell. The spacing in frequency of the higher rim partials has an important effect on the tonal quality of the bell. Investigations into the partial frequencies of 2752 bells, both bronze and steel, of a wide variety of dates, founders and sizes, show a simple and unexpected relationship between the frequencies of the rim partials. This relationship explains why attempts to tune the higher rim partials independently have failed. A modified version of Chladni’s law provides insight into the musical relationship of the partials, and predicts the partials of individual bells well, but fails to give a simple model of the spacing between the partials seen in bells with different profiles

CareTrack Australia: assessing the appropriateness of adult healthcare: protocol for a retrospective medical record review

Introduction: In recent years in keeping with international best practice, clinical guidelines for common conditions have been developed, endorsed and disseminated by peak national and professional bodies. Yet evidence suggests that there remain considerable gaps between the care that is regarded as appropriate by such guidelines and the care received by patients. With an ageing population and increasing treatment options and expectations, healthcare is likely to become unaffordable unless more appropriate care is provided. This paper describes a study protocol that seeks to determine the percentage of healthcare encounters in which patients receive appropriate care for 22 common clinical conditions and the reasons why variations exist from the perspectives of both patients and providers. Methods/design: A random stratified sample of at least 1000 eligible participants will be recruited from a representative cross section of the adult Australian population. Participants' medical records from the years 2009 and 2010 will be audited to assess the appropriateness of the care received for 22 common clinical conditions by determining the percentage of healthcare encounters at which the care provided was concordant with a set of 522 indicators of care, developed for these conditions by a panel of 43 disease experts. The knowledge, attitudes and beliefs of participants and healthcare providers will be examined through interviews and questionnaires to understand the factors influencing variations in care.Tamara D Hunt, Shanthi A Ramanathan, Natalie A Hannaford, Peter D Hibbert, Jeffrey Braithwaite, Enrico Coiera, Richard O Day, Johanna I Westbrook, William B Runcima

Non-Standard Errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Photographs and Poems from the Outer Hebrides

Stornaway Girl, Storm at the Braighe, Side Slipping, On yacht \u27Solus\u27 bound for Rhenish Point, Mussel Raft, Loch Roag, Johina Macleod does her washing. Shawbost, Lewis 1992, Sea wall at the Braighe, Pilot Whale stranding at Dalbeg, HOGMANAY, HARRIS FESTIVAL, IN STORNOWAY, OFF ARDGLAS, SINGING IN THE ASH-HEAP, A\u27CHLIAT

Assessing the appropriateness of prevention and management of venous thromboembolism in Australia : a cross-sectional study

Objectives: The prevention and management of venous thromboembolism (VTE) is often at variance with guidelines. The CareTrack Australia (CTA) study reported that appropriate care (in line with evidence-based or consensus-based guidelines) is being provided for VTE at just over half of eligible encounters. The aim of this paper is to present and discuss the detailed CTA findings for VTE as a baseline for compliance with guidelines at a population level. Setting: The setting was 27 hospitals in 2 states of Australia. Participants: A sample of participants designed to be representative of the Australian population was recruited. Participants who had been admitted overnight during 2009 and/or 2010 were eligible. Of the 1154 CTA participants, 481(42%) were admitted overnight to hospital at least once, comprising 751 admissions. There were 279 females (58%), and the mean age was 64 years. Primary and secondary outcome measures: The primary measure was compliance with indicators of appropriate care for VTE. The indicators were extracted from Australian VTE clinical practice guidelines and ratified by experts. Participants' medical records from 2009 to 2010 were analysed for compliance with 38 VTE indicators. Results: Of the 35 145 CTA encounters, 1078 (3%) were eligible for scoring against VTE indicators. There were 2–84 eligible encounters per indicator at 27 hospitals. Overall compliance with indicators for VTE was 51%, and ranged from 34% to 64% for aggregated sets of indicators. Conclusions: The prevention and management of VTE was appropriate for only half of the at-risk patients in our sample; this provides a baseline for tracking progress nationally. There is a need for national and, ideally, international agreement on clinical standards, indicators and tools to guide, document and monitor care for VTE, and for measures to increase their uptake, particularly where deficiencies have been identified.8 page(s

Towards the delivery of appropriate health care in Australia

4 page(s