Evaluation of an Algorithm for the Automatic Detection of Salient Frequencies in Individual tracks of Multi-track Musical Recording

This paper evaluates the performance of a salient frequency detection algorithm. The algorithm calculates each FFT bin maximum as the maximum value of that bin across an audio region and identifies the FFT bin maximum peaks with the highest five deemed to be the most salient frequencies. To determine the algorithm’s efficacy test subjects were asked to identify the salient frequencies in eighteen audio tracks. These results were compared against the algorithm’s results. The algorithm was successful with electric guitars but struggled with other instruments and in detecting secondary salient frequencies. In a second experiment subjects equalised the same audio tracks using the detected peaks as fixed centre frequencies. Subjects were more satisfied than expected when using these frequencie

An investigation into the efficacy of methods commonly employed by mix engineers to reduce frequency masking in the mixing of multitrack musical recordings

Studio engineers use a variety of techniques to reduce frequency masking between instruments when mixing multi-track musical recordings. This study evaluates the efficacy of three techniques, namely mirrored equalization, frequency spectrum sharing and stereo panning, against their variations to confirm the veracity of accepted practice. Mirrored equalisation involves boosting one instrument and cutting the other at the same frequency. Frequency spectrum sharing involves low pass filtering one instrument and high pass filtering the other. Panning involves placing two competing instruments at different pan positions. Test subjects used eight tools comprising a single unlabeled slider to reduce frequency masking in several two instrument scenarios. Satisfaction values were recorded. Results indicate subjects preferred using tools that panned both audio tracks

Exploring the Container Metaphor for Equalisation Manipulation

This paper presents the first stage in the design and evaluation of a novel container metaphor interface for equalisation control. The prototype system harnesses the Pepper's Ghost illusion to project mid-air a holographic data visualisation of an audio track's long-term average and real-time frequency content as a deformable shape manipulated directly via hand gestures. The system uses HTML 5, JavaScript and the Web Audio API in conjunction with a Leap Motion controller and bespoke low budget projection system. During subjective evaluation users commented that the novel system was simpler and more intuitive to use than commercially established equalisation interface paradigms and most suited to creative, expressive and explorative equalisation tasks

Audio interfaces should be designed based on data visualisation first principles

Audio mixing interfaces (AMIs) commonly conform to a small number of paradigms. These paradigms have significant shortcomings. Data visualisation first principles should be employed to consider alternatives. Existing AMI paradigms are discussed and concepts of image theory and elementary perceptual elements outlined. AMIs should be evaluated by usability experiments however performing these properly is time-consuming. There are many data visualisation options and combinations. Collaboration with others would enable a greater range to be explored. Better understanding data visualisation will benefit audio and music interface development in general

Novel Designs for the Audio Mixing Interface Based on Data Visualisation First Principles

Given the shortcomings of current audio mixing interfaces (AMIs) this study focuses on the development of alternative AMIs based on data visualisation first principles. The elementary perceptual tasks defined by Cleveland informed the design process. Two design ideas were considered for pan: using the elementary perceptual tasks ‘scale’ to display pan on either a single or multiple horizontal lines. Four design ideas were considered for level: using ‘length’, ‘area’, ‘saturation’ or ‘scalable icon’ for visualisation. Each level idea was prototyped with each pan idea, totalling eight novel interfaces. Seven subjects undertook a usability evaluation, replicating a 16 channel reference mix with each interface. Results showed that ‘scalable icons’, especially on multiple horizontal lines appear to show potential

Formal usability evaluation of audio track widget graphical representation for two-dimensional stage audio mixing interface

The two-dimensional stage paradigm (2DSP) has been suggested as an alternative audio mixing interface (AMI). This study seeks to refine the 2DSP by formally evaluating graphical track visualisation styles. Track visualisations considered were text only, circles containing text, individually coloured circles containing text, circles colour coded by instrument type with text, icons with text superimposed, circles with RMS related dynamic opacity and a traditional AMI. The usability evaluation focused on track selection efficiency and included user visualisation preference for this micro-task. Test subjects were instructed to click five randomly selected tracks for a six, sixteen and thirty-two track mix for each visualisation. The results indicate text only visualisation is best for efficiency however test subjects preferred icons and traditional AMI

LAMI: A gesturally controlled three-dimensional stage Leap (Motion-based) Audio Mixing Interface

Interface designers are increasingly exploring alternative approaches to user input/control. LAMI is a Leap (Motion-based) AMI which takes user’s hand gestures and maps these to a three-dimensional stage displayed on a computer monitor. Audio channels are visualised as spheres whose Y coordinate is spectral centroid and X and Z coordinates are controlled by hand position and represent pan and level respectively. Auxiliary send levels are controlled via wrist rotation and vertical hand position and visually represented as dial-like arcs. Channel EQ curve is controlled by manipulating a lathed column visualisation. Design of LAMI followed an iterative design cycle with candidate interfaces rapidly prototyped, evaluated and refined. LAMI was evaluated against Logic Pro X in a defined audio mixing task

Changes in acute hospital costs after employing clinical facilitators to improve stroke care in Victoria, Australia

BackgroundHospital costs for stroke are increasing and variability in care quality creates inefficiencies. In 2007, the Victorian Government (Australia) employed clinical facilitators for three years in eight public hospitals to improve stroke care. Literature on the cost implications of such roles is rare. We report changes in the costs of acute stroke care following implementation of this program.MethodsObservational controlled before-and-after cohort design. Standardised hospital costing data were compared pre-program (financial year 2006-07) and post-program (2010-11) for all admitted episodes of stroke or transient ischaemic attack (TIA) using ICD-10 discharge codes. Costs in Australian dollars (AUD) were adjusted to a common year 2010. Generalised linear regression models were used for adjusted comparisons.ResultsA 20% increase in stroke and TIA episodes was observed: 2624 pre-program (age>75years: 53%) and 3142 post-program (age>75years: 51%); largely explained by more TIA admissions (up from 785 to 1072). Average length of stay reduced by 22% (pre-program 7.3days to post-program 5.7days, pPeer reviewe

Variability in Demand for Special Education Teachers: Indicators, Explanations, and Impacts

After decades of growth, the number of special education teachers (SETs) has begun to decline. In 2009, U.S. schools employed 13% fewer SETs than in 2006. The number of annual new hires of SETs also dropped dramatically in some states. The onset of these declines predated the economic downturn of 2008 and resulted in part from a steady decline since 2005 in the number of students with disabilities (SWD) served. We consider factors that may be contributing to declining demand for SETs, among them the number of SWD, service delivery, the economic downturn, and present supporting evidence. We also consider the potential impact of reduced demand on SET supply, teacher education, equitable distribution of teachers, and, most importantly, outcomes for SWD. We call for vigilance and monitoring of SET employment data to assure that all students receive the appropriate education to which they are entitled