269 research outputs found
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Extraordinary Emergencies: Reproducing Moral Discourses of the Child in Institutional Interaction
This report uses audio recorded telephone calls and textual data from an emergency medical services call center to examine the interactional practices through which speakers produce what we call “extraordinary emergencies”, treating the events concerned as requiring moral, as well as medical, attention. Since one of the overarching institutional aims of emergency call centers is to facilitate the efficient provision of medical services, call-takers typically treat reported emergencies as routine events. However, in some instances speakers produce practices that do not contribute toward the institutional agenda of providing medical assistance, thereby treating them as extraordinary cases. These practices occurred recurrently in calls involving reports of emergencies relating to child sexuality, including sexual assaults against children and obstetric emergencies where the mother was particularly young. We discuss the implications of these findings for the situated reproduction of particular moral norms, especially with respect to the category of the child in society
Extraordinary emergencies : reproducing the sacred child in institutional interaction.
This research report examines telephonic and written data from an emergency medical services centre
in the Western Cape and seeks to uncover the language practices that speakers use in order to create
what I term “extraordinary emergencies”. Since one of the overarching institutional aims of the
emergency call centre is that of “preservation of life”, the majority of emergencies are reproduced by
emergency call-takers as routine events, specifically for the purpose of managing them most
efficiently and thus working towards the institutional aim of preserving life. However, in certain
instances, this institutional agenda is temporarily halted or abandoned in favour of a competing
agenda, what I have termed the “personal” agenda enacted by the speaker. This personal agenda
works to the reproduction of particular norms and values, and speakers are seen as morally
accountable for reproducing them. This research report makes use of discursive analytic practices,
specifically conversation analysis, as a method by which to highlight subtle and delicate moments in
the interaction that recreate the shared value of the “sacred child” in real-time interaction.
Keywords: emergency, childhood, sexual assault, conversation analysis, institution
Spatial sampling and beamforming for spherical microphone arrays
Spherical microphone arrays have been recently studied for spatial sound
recording, speech communication, and sound field analysis for room acoustics
and noise control. Complementary theoretical studies presented progress in
spatial sampling and beamforming methods. This paper reviews recent results in
spatial sampling that facilitate a wide range of spherical array
configurations, from a single rigid sphere to free positioning of microphones.
The paper then presents an overview of beamforming methods recently presented
for spherical arrays, from the widely used delay-and-sum and Dolph-Chebyshev,
to the more advanced optimal methods, typically performed in the spherical
harmonics domain
Zones of quiet in a broadband diffuse sound field
The zones of quiet in pure-tone diffuse sound fields have been studied
extensively in the past, both theoretically and experimentally, with the well
known result of the 10\,dB attenuation extending to about a tenth of a
wavelength. Recent results on the spatial-temporal correlation of broadband
diffuse sound fields are used in this study to develop a theoretical framework
for predicting the extension of the zones of quiet in broadband diffuse sound
fields. This can be used to study the acoustic limitations imposed on local
active sound control systems such as an active headrest when controlling
broadband noise. Spatial-temporal correlation is first revised, after which
derivations of the diffuse field zones of quiet in the near-field and the
far-field of the secondary source are presented. The theoretical analysis is
supported by simulation examples comparing the zones of quiet for diffuse
fields excited by tonal and broadband signals. It is shown that as a first
approximation the zone of quiet of a low-pass filtered noise is comparable to
that of a pure-tone with a frequency equal to the center frequency of the
broadband noise bandwidth
Bearing-only acoustic tracking of moving speakers for robot audition
This paper focuses on speaker tracking in robot audition for human-robot interaction. Using only acoustic signals, speaker tracking in enclosed spaces is subject to missing detections and spurious clutter measurements due to speech inactivity, reverberation and interference. Furthermore, many acoustic localization approaches estimate speaker direction, hence providing bearing-only measurements without range information. This paper presents a probability hypothesis density (PHD) tracker that augments the bearing-only speaker directions of arrival with a cloud of range hypotheses at speaker initiation and propagates the random variates through time. Furthermore, due to their formulation PHD filters explicitly model, and hence provide robustness against, clutter and missing detections. The approach is verified using experimental results
Rendering Binaural Room Impulse Responses from Spherical Microphone Array Recordings Using Timbre Correction
The technique of rendering binaural room impulse responses from spatial data captured by spherical microphone arrays has been recently proposed and investigated perceptually. The finite spatial resolution enforced by the microphone configuration restricts the available frequency bandwidth and, accordingly, modifies the perceived timbre of the played-back material. This paper presents a feasibility study investigating the use of filters to correct such spectral artifacts. Listening tests are employed to gain a better understanding of how equalization affects externalization, source focus and timbre. Preliminary results suggest that timbre correction filters improve both timbral and spatial perception
Optimal model-based beamforming and independent steering for spherical loudspeaker arrays
Spherical loudspeaker arrays have been recently studied for directional sound
radiation, where the compact arrangement of the loudspeaker units around a
sphere facilitated the control of sound radiation in three-dimensional space.
Directivity of sound radiation, or beamforming, was achieved by driving each
loudspeaker unit independently, where the design of beamforming weights was
typically achieved by numerical optimization with reference to a given desired
beam pattern. This is in contrast to the methods already developed for
microphone arrays in general and spherical microphone arrays in particular,
where beamformer weights are designed to satisfy a wider range of objectives,
related to directivity, robustness, and side-lobe level, for example. This
paper presents the development of a physical-model-based, optimal beamforming
framework for spherical loudspeaker arrays, similar to the framework already
developed for spherical microphone arrays, facilitating efficient beamforming
in the spherical harmonics domain, with independent steering. In particular, it
is shown that from a beamforming perspective, the spherical loudspeaker array
is similar to the spherical microphone array with microphones arranged around a
rigid sphere. Experimental investigation validates the theoretical framework of
beamformer design
Study of speaker localization with binaural microphone array incorporating auditory filters and lateral angle estimation
Speaker localization for binaural microphone arrays has been widely studied
for applications such as speech communication, video conferencing, and robot
audition. Many methods developed for this task, including the direct path
dominance (DPD) test, share common stages in their processing, which include
transformation using the short-time Fourier transform (STFT), and a direction
of arrival (DOA) search that is based on the head related transfer function
(HRTF) set. In this paper, alternatives to these processing stages, motivated
by human hearing, are proposed. These include incorporating an auditory filter
bank to replace the STFT, and a new DOA search based on transformed HRTF as
steering vectors. A simulation study and an experimental study are conducted to
validate the proposed alternatives, and both are applied to two binaural DOA
estimation methods; the results show that the proposed method compares
favorably with current methods
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