A scientific approach to microphone placement for cymbals in live sound

Current practice regarding overhead microphone placement on drum kits at live events is largely informed by personal experience and industry-standard practice, where there seems to be a lack of scientific evidence supporting these placements. This research addresses this by first recordings from points around different cymbals which are struck by three types of drumsticks. The measurements are processed in MATLAB to produce visual representations of the auditory data. The work puts forward evidence that cymbal radiation patterns are dependent on shape, size, profile and striking method while the attack and sustain are primarily dependent on cymbal weight. Ideal overhead microphone placement diagrams are generated based on these results to give live sound engineers a quick reference guide for best practice at live events

Subjective evaluation of an emerging theory of low-frequency sound source localization in closed acoustic spaces

An earlier reported theory of low-frequency sound-source localization within closed acoustic spaces proposed that virtual image acuity is strongly dependent on sufficient inter-arrival time between a direct sound and its first reflection. This current study aims to test the theory’s predictions by subjective experiment where participants are required to indicate perceived sound source direction, but without knowledge of loudspeaker location. Test signals of frequencies 40 Hz to 115 Hz take the form of either windowed sine or square waves. Results confirm broad agreement with theoretical expectations and support the conjecture, contrary to common expectation, that low-frequency sound localization within the context of closed acoustic spaces is possible, although strongly dependent on system configuration and size of a listening space

Low-frequency sound source localization as a function of closed acoustic spaces

Further development of an emerging generalized theory of low-frequency sound localization in closed listening spaces is presented that aims to resolve the ambiguities inherent in previous research. The approach takes a robust set of equations based on source/listener location, reverberation time and room dimensions and tests them against a set of evaluation procedures to explore image location against theoretical expectations. Phantom imaging is germane to the methodology and its match within the theoretical framework is investigated. Binaural recordings are used to inspect a range of closed environments for localization clues each with a range of source-listener placements. A complementary series of small-scale listening tests are included for perceptual validation

Towards a generalized theory of low-frequency sound source localization

Low-frequency sound source localization generates considerable amount of disagreement between audio/acoustics researchers, with some arguing that below a certain frequency humans cannot localize a source with others insisting that in certain cases localization is possible, even down to the lowest audible of frequencies. Nearly all previous work in this area depends on subjective evaluations to formulate theorems for low-frequency localization. This, of course, opens the argument of data reliability, a critical factor that may go some way to explain the reported ambiguities with regard to low-frequency localization. The resulting proposal stipulates that low-frequency source localization is highly dependent on room dimensions, source/listener location and absorptive properties. In some cases, a source can be accurately localized down to the lowest audible of frequencies, while in other situations it cannot. This is relevant as the standard procedure in live sound reinforcement, cinema sound and home-theater surround sound is to have a single mono channel for the low-frequency content, based on the assumption that human’s cannot determine direction in this band. This work takes the first steps towards showing that this may not be a universally valid simplification and that certain sound reproduction systems may actually benefit from directional low-frequency content

Live sound subwoofer system performance quantification.

The general aim of live sound reinforcement is to deliver an appropriate and consistent listening experience across an audience. Achieving this in the subwoofer range (typically between 20 – 100 Hz) has been the focus of previous work, where techniques have been developed to allow for consistent sound energy distribution over a wide area. While this provides system designers with a powerful set of tools, it brings with it many potential metrics to quantify performance. This research identifies key indicators of subwoofer system performance and proposes a single weighted metric to quantify overall performance. Both centrally-distributed and left/right configurations are analyzed using the new metric to highlight functionality.N/

Analysis, modeling and wide-area spatiotemporal control of low-frequency sound reproduction

This research aims to develop a low-frequency response control methodology capable of delivering a consistent spectral and temporal response over a wide listening area. Low-frequency room acoustics are naturally plagued by room-modes, a result of standing waves at frequencies with wavelengths that are integer multiples of one or more room dimension. The standing wave pattern is different for each modal frequency, causing a complicated sound field exhibiting a highly position-dependent frequency response. Enhanced systems are investigated with multiple degrees of freedom (independently-controllable sound radiating sources) to provide adequate low-frequency response control. The proposed solution, termed a chameleon subwoofer array or CSA, adopts the most advantageous aspects of existing room-mode correction methodologies while emphasizing efficiency and practicality. Multiple degrees of freedom are ideally achieved by employing what is designated a hybrid subwoofer, which provides four orthogonal degrees of freedom configured within a modest-sized enclosure. The CSA software algorithm integrates both objective and subjective measures to address listener preferences including the possibility of individual real-time control. CSAs and existing techniques are evaluated within a novel acoustical modeling system (FDTD simulation toolbox) developed to meet the requirements of this research. Extensive virtual development of CSAs has led to experimentation using a prototype hybrid subwoofer. The resulting performance is in line with the simulations, whereby variance across a wide listening area is reduced by over 50% with only four degrees of freedom. A supplemental novel correction algorithm addresses correction issues at select narrow frequency bands. These frequencies are filtered from the signal and replaced using virtual bass to maintain all aural information, a psychoacoustical effect giving the impression of low-frequency. Virtual bass is synthesized using an original hybrid approach combining two mainstream synthesis procedures while suppressing each method‟s inherent weaknesses. This algorithm is demonstrated to improve CSA output efficiency while maintaining acceptable subjective performance

Three Models for Educating for Empathy and Humanization through Values Dialogue in Secondary School Classes

This thesis develops educable constructs of empathy and of humanization as well as a theory, a praxis, educational models, and measuring instruments of values dialogue that hypothetically can be used to foster and to measure changes in empathic and humanizing capacities among secondary school students. The theory and the praxis of values dialogue utilize a sample of Western epistemological philosophy, as well as some of the research and literature of the field of dialogic inquiry. This study then assembles educable constructs of empathy and of humanization by reviewing related research and scholarship. The empathy constructs consist of emotional literacy and of role-taking, while the humanizing construct consists of mutualities, the latter concept denoting ontological and epistemological elements, processes, understandings, and capacities that potentially can be shared among all human beings. This paper then establishes three educational models of values dialogue that can hypothetically foster the former constructs, each model nurturing one of them predominately. Next, this study outlines the procedures of the execution of the models and the assessments that double as potential instruments for testing for the presence of this study’s targeted empathic and humanistic capacities. Therefore, this study presents a testable hypothesis consisting of models of values dialogue which are intended to foster empathy and humanization. This hypothesis must be empirically tested to condone or to refute the merit of values dialogue

The effect of performance stages on subwoofer polar and frequency responses

Precise control of low-frequency energy is a common requirement at large-scale live events, whereby sound energy transmitted into performance areas and outside event grounds must be limited. Industry-standard sound system design and prediction software typically omits any acoustical effect a performance stage will have on the overall system response (both in terms of polar and frequency response).This research highlights the significant effect a stage can have on subwoofer performance, where in particularly poor cases directionality is lost and the frequency response is strongly colored by resonances. This work puts forward recommendations for subwoofer system configurations that avoid unwanted stage effects as much as possible to maintain the desired (and predicted) system performance