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

The Mass Growth and Stellar Ages of Galaxies: Observations versus Simulations

Using observed stellar mass functions out to $z=5$, we measure the main progenitor stellar mass growth of descendant galaxies with masses of $\log{M_{*}/M_{\odot}}=11.5,11.0,10.5,10.0$ at $z\sim0.1$ using an evolving cumulative number density selection. From these mass growth histories, we are able to measure the time at which half the total stellar mass of the descendant galaxy was assembled, $t_{a}$, which, in order of decreasing mass corresponds to redshifts of $z_{a}=1.28, 0.92, 0.60$ and $0.51$. We compare this to the median light-weighted stellar age $t_{*}$ ($z_{*} = 2.08, 1.49, 0.82$ and $0.37$) of a sample of low redshift SDSS galaxies (from the literature) and find the timescales are consistent with more massive galaxies forming a higher fraction of their stars ex-situ compared to lower mass descendants. We find that both $t_{*}$ and $t_{a}$ strongly correlate with mass which is in contrast to what is found in the EAGLE hydrodynamical simulation which shows a flat relationship between $t_{a}$ and $M_{*}$. However, the semi-analytic model of \citet{henriques2015} is consistent with the observations in both $t_{a}$ and $t_{*}$ with $M_{*}$, showing the most recent semi-analytic models are better able to decouple the evolution of the baryons from the dark matter in lower-mass galaxies.Comment: 6 pages, 3 figures, accepted for publication in ApJ

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/

“Inspiring Imps”: programme evaluation of a football intervention targeting mentally ill health services users through a professional football club

The Active People survey (2010) shows that only 6.5% of disabled individuals participate in sport and exercise 3 times per week, compared with 16.5% of able bodied adults in the UK. Individuals with recognised disabilities have long been excluded from mainstream society. Particularly in sport, disability athletes can be afforded minority status and are treated as such (Nixon, 2000: In Handbook of Sports Studies, edited by J. Coakley and E. Dunning. London: Sage). This stigmatisation can be particularly acute among participants with diagnosed mental or psychological disabilities. Previous research concluded that sport can have positive psychological and social benefits, including improved well-being, motivation and social confidence (Crone and Guy, 2008: International Journal of Mental Health Nursing. 17, 197-207.). The aim of the present study was to investigate the feasibility of a 6 week exercise programme targeting mental ill health service users aged 16+. A weekly 2 hour session of football was introduced to promote health and wellbeing in the target group. Partners included county Football Association and a professional football club. The project enhanced local partnerships and partnerships with other professional football clubs. The key remaining aim is to ensure a sustainable “legacy” is achieved to ensure the continuation delivery of the project. The feasibility of the present study will be assessed using programme evaluation. Programme evaluation uses programme theory to produce a structured framework for assessment of the project (Rossi et al 2004; Evaluation: A systematic Approach. London, Sage). This allows a clear and logical progression from planning to implementation. Participant attrition rates and attendance records will be collected. These data will be supplemented with semi-structured interviews with participants and project stakeholders to assess programme development. The expected overall project outcome is to produce shared learning practice on similar interventions nationwide

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

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