The Effect of Interchannel Time Difference on Localisation in Vertical Stereophony

Listening tests were conducted in order to analyse the localisation of band-limited stimuli in vertical stereophony. The test stimuli were seven octave bands of pink noise, with centre frequencies ranging from 125–8000Hz, as well as broadband pink noise. Stimuli were presented from vertically arranged loudspeakers either monophonically or as vertical phantom images, created with the upper loudspeaker delayed with respect to the lower by 0, 0.5, 1, 5 and 10ms (i.e. interchannel time difference). The experimental data obtained showed that localisation under the aforementioned conditions is generally governed by the so-called “pitch-height” effect, with the high frequency stimuli generally being localised significantly higher than the low frequency stimuli for all conditions. The effect of interchannel time difference was found to be significant on localisation judgments for both the 1000-4000Hz octave bands and the broadband pink noise; it is suggested that this was related to the effects of comb filtering. Additionally, no evidence could be found to support the existence of the precedence effect in vertical stereophony

Psychoacoustic Considerations in Surround Sound with Height

This paper presents recent research findings in the psychoacoustics of 3D multichannel sound recording and rendering. The addition of height channels in new reproduction formats such as Auro-3D, Dolby Atmos and 22.2, etc. enhances the perceived spatial impression in reproduction. To achieve optimal acoustic recording and signal processing for such formats, it is first important to understand the fundamental principles of how we perceive sounds reproduced from vertically oriented stereophonic loudspeakers. Recent studies by the authors in this field provide insights into how such principles can be applied for practical 3D recording and upmixing. Topics that are discussed in this paper include the interchannel level and time difference relationships in terms of vertically induced interchannel crosstalk, the effectiveness of the precedence effect in the vertical plane, the aspect of tonal coloration resulting from vertical stereophonic reproduction, the effect of vertical microphone spacing on envelopment, the effect of interchannel decorrelation, and the use of spectral cues for extending vertical image spread

Validation of the paediatric triage tape

Assessment of physiological parameters forms an essential part of the clinical assessment of an injured or ill child. However, the evidence base for the values that we currently accept and teach as "normal" ranges of heart rate and respiratory rate is poor. This thesis studied 1109 healthy, resting schoolchildren aged four to 16 years in Plymouth, England, and derived reference ranges of heart rate and respiratory rate from this sample. A study was then undertaken in a deprived area of Cape Town, South Africa, to examine the heart and respiratory rates of 346 healthy, resting schoolchildren aged five to 16 years. This sample was similar by height and weight to the British sample, and their heart and respiratory rates were compared. There was no difference in median heart rate in the two groups, but a small statistically significant difference in respiratory rate. However, this difference was too small to be clinically significant, being less than one breath per minute. As there were no diferneces in physiology between the two countries, the validation of the Paeditric Triage Tape could take place in South Africa and the results be applied in the United Kingdom. The third stage of this thesis consisted of a Delphi study to derive consensus based criteria against which major incident triage tools may be tested, as the current testing standards (most commonly, the Injury Severity Score (ISS)) are not appropriate for use in a major incident setting. The criteria thus derived were used as part of the validation process for the Paediatric Triage Tape (PTT), a simple to use vinyl tape that is used for primary triage of children in major incident situations. The validation also proceeded against more typical measurement standards, including the The validation took place in Cape Town, against a prospective sample of 3461 injured children. The PTT was found to have very poor sensitivity (that is, it missed many of the seriously injured children and many of the children in need of immediate medical intervention), although it had excellent specificity. The overtriage and undertriage rates were within the limits currently held to be acceptable. The PTT was compared to other major incident triage tools and found to have similar performance to Careflight methodology. Both the START and JumpSTART algorithms performed very poorly and should be discontinued from use. The PTT needs redesigning and revalidating, or replacing by a more robust primary triage tool. In the meantime, all primary triage tools for children in this setting should be used with caution

Vertical Stereophonic Localisation in the Presence of Interchannel Crosstalk: the Analysis of Frequency- Dependent Localisation Thresholds

Listening tests were conducted in order to investigate the frequency dependency of localization thresholds in relation to vertical interchannel crosstalk. Octave band and broadband pink noise stimuli were presented to subjects as phantom images from vertically arranged stereophonic loudspeakers located directly in front of the listening position. With respect to the listening position the lower loudspeaker was not elevated; the upper loudspeaker was elevated by 30◦. Subjects completed a method of adjustment task in which they were required to reduce the amplitude of the upper loudspeaker until the resultant phantom image matched the position of the same stimulus presented from the lower loudspeaker alone. The upper loudspeaker was delayedwith respect to the lower by 0, 0.5, 1, 5, and 10 ms. The experimental data demonstrated that the main effect of frequency on the localization threshold was significant, with the low frequency stimuli (125 and 250 Hz) requiring significantly less level reduction (less than 6 dB) than the mid-high (1, 2, and 8 kHz) frequency stimuli (9–10.5 dB reduction). The main effect of interchannel time difference (ICTD) on the localization thresholds for each octave band was found to be non-significant. For all stimuli interchannel level difference (ICLD) was always necessary, indicating that the precedence effect is not a feature of median plane localization

The Emergency Management and Treatment of Severe Burns

Burn injuries continue to cause morbidity and mortality internationally. Despite international collaborations and preventative measures, there are still many cases reported in high- and low-income countries. The treatment of these patients is often protracted and requires extensive resources. The adequate resuscitation of these patients coupled with meticulous wound care can have a huge impact on their outcome. The authors present a simple guideline for the initial management of severe burns which is utilised by the South African Burn Society and is based on the guidelines of the American Burn Association and the Australian and New Zealand Burn Association

Exposure to daily trauma: The experiences and coping mechanism of Emergency Medical Personnel. A cross-sectional study

IntroductionTo investigate the experience and coping mechanisms used by Emergency Medical Services (EMS) personnel following exposure to daily or routine traumatic events.MethodsA total of 189 respondents from three EMS in the Cape Town Metropole completed a questionnaire, containing close-ended quantitative questions. This was followed up by a semi-structured interview in order to get greater insight from in-depth qualitative data.ResultsThe significant results of this study indicate that EMS personnel find dealing with seriously injured children most traumatic. They experience avoidance symptoms after exposure to a traumatic incident and apply emotion-focused coping to help them deal with their emotions. Very little or no training has been received to prepare them for the emotional effects of traumatic incidents or how to deal with the bereaved family, and there was consensus amongst the participants that their company debriefings and support structures are inadequate.ConclusionEMS personnel are exposed to critical incidents on a daily basis. Commonly used emotion-focused coping mechanisms are not effective in long-term coping. A key recommendation emanating from this finding is that integrated intervention programmes are needed to assist EMS personnel working in this sustained high-stress environment. The findings can assist health care educators in the design of co-curricular activities intended to help in the development of resilience and the psychological wellbeing of EMS personnel. Policy makers and EMS managers may find the results useful as they evaluate the effectiveness of their current debriefing and support structures