Vocal tract resonances and the sound of the Australian didjeridu (yidaki) II. Theory.

The didjeridu (didgeridoo) or yidaki of the Australian Aboriginal people consists of the narrow trunk of a small Eucalypt tree that has been hollowed out by the action of termites, cut to a length of about 1.5 m, smoothed, and decorated. It is lip-blown like a trumpet and produces a simple drone in the frequency range 55 to 80 Hz. Interest arises from the fact that a skilled player can make a very wide variety of sounds with formants rather like those of human vowels, and can also produce additional complex sounds by adding vocalization. An outline is given of the way in which the whole system can be analyzed using the harmonic-balance technique, but a simpler approach with lip motion assumed shows easily that upper harmonics of the drone with frequencies lying close to impedance maxima of the vocal tract are suppressed, so that formant bands appear near impedance minima of the vocal tract. This agrees with experimental findings. Simultaneous vibration of the player's lips and vocal folds is shown to generate multiple sum and difference tones, and can be used to produce subharmonics of the drone. A brief discussion is given of player preference of particular bore profiles.

Acoustic impedance measurements-correction for probe geometry mismatch.

The effect of evanescent mode generation, due to geometrical mismatch, in acoustic impedance measurements is investigated. The particular geometry considered is that of a impedance probe with an annular flow port and a central microphone, but the techniques are applicable to other geometries. It is found that the imaginary part of the measured impedance error is proportional to frequency, and that the sign of the error is positive for measurements made on tubes with diameter much larger than that of the inlet port, but negative for tubes with diameter close to that of the inlet. The result is a distortion of the measured frequencies of the impedance minima of the duct while the maxima are largely unaffected. There is, in addition, a real resistive component to the error that varies approximately as the square root of the frequency. Experiment confirms the results of the analysis and calculations, and a calibration procedure is proposed that allows impedance probes that have been calibrated on a semi-infinite tube of one diameter to be employed for measurements on components with an inlet duct of some very different diameter.

Rotational aerophones.

Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates slat rotation frequency to slat width and velocity through the air. Analysis shows that sound production is due to generation of an oscillating-rotating dipole across the slat, the role of the vortices shed by the slat being relatively minor. Apparent discrepancies between the behavior of a bullroarer slat and a slat mounted on an axle in a wind tunnel are shown to be due to viscous friction in the bearings of the wind-tunnel experiment.

Bell clapper impact dynamics and the voicing of a carillon.

The periodic re-voicing of the bell clappers of the Australian National Carillon in Canberra provided an opportunity for the study of the acoustic effects of this operation. After prolonged playing, the impact of the pear-shaped clapper on a bell produces a significant flat area on both the clapper and the inside surface of the bell. This deformation significantly decreases the duration of the impact event and has the effect of increasing the relative amplitude of higher modes in the bell sound, making it "brighter" or even "clangy." This effect is studied by comparing the spectral envelope of the sounds of several bells before and after voicing. Theoretical analysis shows that the clapper actually strikes the bell and remains in contact with the bell surface until it is ejected by a displacement pulse that has traveled around the complete circumference of the bell. The contact time, typically about 1 ms, is therefore much longer than the effective impact time, which is only a few tenths of a millisecond. Both the impact time and the contact time are reduced by the presence of a flat on the clapper.

Blowing pressure, power, and spectrum in trumpet playing.

Measurements of sound output as a function of blowing pressure are reported for a group of experienced trumpet players. The study identifies several common features, namely (1) a threshold blowing pressure approximately proportional to the frequency of the note being played, (2) an extended region in which the sound output rises by about 15 dB for each doubling of blowing pressure, and (3) a saturation region in which sound output rises by only about 3 dB for a doubling of blowing pressure. Some players are able to blow with maximum pressures as high as 25 kPa, which is significantly greater than normal systolic blood pressure. A simple theory is presented that provides a physical explanation for the acoustical behavior, but a detailed treatment requires solution of the nonlinear coupled equations both for the lip-valve mechanism and for nonlinear wave propagation in the instrument tube. Frequency analysis of the sound shows a basic spectral envelope determined by the resonance properties of the mouthpiece cup and the radiation behavior of the bell, supplemented by an extension to increasingly high frequencies as the blowing pressure is increased. This high-frequency behavior can be attributed to nonlinear wavefront steepening during sound propagation along the cylindrical bore of the instrument.

Borderline personality. A review of recent research.

Borderline personality has been, for many years, a discredited diagnostic concept. In 1979 a review of the literature concluded that its validity status was very uncertain. The authors have reviewed research conducted since then and discuss it in terms of the Robins & Guze (1970) criteria. In spite of existing unclear issues, the balance is tipping in favour of the validity of borderline personality, as diagnosed with new research criteria. This development is taking place in the context of a growing interest in the area of personality disorders.

Minor psychiatric morbidity and general practice consultation: the West London Survey.

Data from a large-scale (N greater than 3000) community survey (the 'West London Survey') were used to examine the effect of minor psychiatric morbidity on the probability of contact with primary medical care, and factors which influenced this effect. The presence of such morbidity was found to double the probability of consulting, and about one-fifth of consultations could be attributed to it. Logistic analysis was used to investigate the joint effect on general practice consultation of minor psychiatric morbidity, three other health-related variables and five sociodemographic variables. It was found, as expected, that the health variables exerted much more influence on consulting than the sociodemographic variables, but that the relationship was characterized by complex interactions between health and sociodemographic variables. In particular, sex, socioeconomic status and minor psychiatric morbidity interacted in their effect on the probability of general practitioner consultation. The findings are interpreted in the context of previous theoretical and empirical work.

Sensitivity to noise in a community sample: I. Measurement of psychiatric disorder and personality.

A sample of 77 women of high and low noise sensitivity, living in areas of high and low exposure to aircraft noise drawn from the 1977 West London Survey, were interviewed in the community in 1980. Women of high, intermediate and low noise sensitivity in 1980 were compared for measures of psychiatric disorder, personality and reactivity to the other sensory stimuli. In addition, the noise sensitivity measures defining the three groups in 1980 were compared with further measures of noise sensitivity. High noise sensitive women exhibited significantly more psychiatric symptoms, higher neuroticism scores, and greater reactivity to other sensory stimuli than intermediate and low noise sensitive women.

Sensitivity to noise in a community sample: II. Measurement of psychophysiological indices.

A sample of 77 women of high and low noise sensitivity in 1977, living in areas of high and low exposure to aircraft noise, were interviewed in the community in 1980. High, intermediate and low noise sensitive women were compared, using measures of blood pressure, heart rate, skin conductance, hearing threshold, uncomfortable loudness level and magnitude estimation of six tones. These physiological measures did not clearly distinguish different noise sensitivity groups, except that highly noise sensitive women had a consistently slower heart rate. Noise sensitivity was not related to auditory threshold. In the high aircraft noise area there were significantly more skin conductance responses than in the low aircraft noise area irrespective of noise sensitivity. This may be the result of chronic exposure to high aircraft noise.

'Borderline personality': diagnostic attitudes at the Maudsley Hospital.

About a quarter of the psychiatrists at the Maudsley Hospital use the diagnosis of 'borderline' personality. The description of the borderline patient obtained in this study does not overlap with any existing ICD personality disorder but has characteristics of the schizoid, paranoid, hysteric, explosive, anankastic and antisocial personalities. The item that discriminated best between borderlines and controls was 'brief, unsystematized , psychotic episodes', which is not included in the DSM-III definitions of borderline diagnoses. Items of the DSM-III 'schizotypal' set--e.g. 'suspiciousness' and 'ideas of reference'--discriminated better between borderline cases and controls, whereas items of the DSM-III 'borderline personality' set--e.g. 'impulsivity' or 'unpredictability'--scored more frequently in both groups. These are similar to American findings.

Self-assessment of health: an exploration of the effects of physical and psychological symptoms.

The clinician has no objective criteria of good health; he is likely to identify its presence only in the absence of disease and dysfunction. Yet the layman is able to give a global assessment of his own health as good, average or poor. The present paper explores the correlates of self-assessment of health in a large community sample and, by the use of two linear models, describes the effects of age, sex, reported symptoms, and long-standing illness on self-rated health status. It is suggested that global ratings are influenced by age and sex and by the experience of both physical and psychological symptoms, and that there are no interactive effects between symptoms and the demographic variables.

Psychiatric admissions and aircraft noise from London Airport: four-year, three-hospitals' study.

Nine thousand persons admitted to three large psychiatric hospitals, over a period of four years, were classified according to the aircraft noise exposure of their home address, using the Noise and Number Index. The analysis searched first for simple associations between exposure and admission rates, then for complex interactions with socio-economic characteristics of the area of residence. There was no common pattern of admissions across the three hospitals: in one case the rates decreased with aircraft noise; in the other two the rates increased with noise exposure. However, since in all cases the trends could be attributed to non-noise factors characteristic of the population, it was concluded that the effects of noise, if any, could only be small, weakly influencing other causal variables but not overriding them. Further analyses showed that positive associations between noise and admissions occurred in some groups and in some districts. People 45 years old and over exhibited higher admission rates than expected in the highest noise zone in one hospital. The districts where a positive trend between noise and admissions was evident were those with a higher proportion of one-person households, a higher proportion of immigrants, or a higher proportion of professionals and managers; however, these results were only found in one hospital with counterexamples in others. No strong, significant noise effect could be found. Limitations of the hospital records and specific difficulties in setting up the data for these studies are discussed.

Factors affecting the consumption of psychotropic drugs.

This paper presents some results from a survey conducted in West London in 1977. The 2-week prevalence of psychotropic drug consumption was found to be 10.9% and almost identical figure to that obtained in an earlier survey conducted 8 years previously. The reasons for the absence of the expected rise in prevalence of consumption are discussed. Consumption was found to be strongly associated with various measures of health, and there was a marked sex difference in drug consumption (females greater than males) which was independent of health.

Aircraft noise and mental health: II. Use of medicines and health care services.

A domiciliary survey (sample size circa 6000) was conducted in areas of different aircraft noise exposure affected by London (Heathrow) Airport. Respondents were urban dwellers aged 16+. Their use of medicines, general practitioner services, hospital facilities and community services were investigated in relation both to the level of aircraft noise and to the degree of annoyance it causes. None of the indicators showed higher uptake in the high noise areas. The relationships between health indicators, noise and annoyance were not uniform. In areas exposed to high noise the use of non-prescribed drugs was significantly higher among 'very annoyed' than among 'less annoyed' respondents. The uptake of psychotropic drugs, and the use of general practice and out-patient services, tended to increase with increasing annoyance both in high- and low-noise areas, but the differences were not in all cases statistically significant. Parallels were drawn between these results and those of earlier analyses of the same survey related to the prevalence of acute and chronic symptoms. Suggestions for the analysis and interpretation of health effects of noise are put forward.

Aircraft noise and mental health: I. Prevalence of individual symptoms.

A domiciliary survey (sample size circa 6000) was conducted in areas of different aircraft noise exposure affected by London (Heathrow) Airport. Respondents were urban dwellers age 16+. Since no differences were found in the prevalence of manifest psychiatric disorders, the frequency of 27 individual acute and chronic symptoms was investigated. Many acute symptoms showed an increase with noise, and this was particularly evident for waking at night, irritability, depression, difficulty in getting to sleep, swollen ankles, burns/cuts/minor accidents, and skin troubles. Two chronic symptoms, tinnitus and ear problems, showed evidence of an increase with noise, while most other chronic symptoms were more common in low noise conditions. Results are controlled for the effects of age, sex and other standard epidemiological variables. Irrespective of their association with noise, most symptoms, chronic and acute, were more frequent among those respondents who also reported high annoyance. Suggestions for the analysis of surveys of health effects by noise are put forward.