Recent interest in high-resolution digital audio has been accompanied by a trend to higher and higher sampling rates and bit depths, yet the sound quality improvements show diminishing returns and so fail to reconcile human auditory capability with the information capacity of the channel. We propose an audio capture, archiving, and distribution methodology based on sampling kernels having finite length, unlike the "ideal" sinc kernel that extends indefinitely. We show that with the new kernels, original transient events need not become significantly extended in time when reproduced. This new approach runs contrary to some conventional audio desiderata such as the complete elimination of aliasing. The paper reviews advances in neuroscience and recent evidence on the statistics of real signals, from which we conclude that the conventional criteria may be unhelpful. We show that this proposed approach can result in improved time/frequency balance in a high-performance chain whose errors, from the perspective of the human listener, are equivalent to those introduced when sound travels a short distance through air.

Intermodulation distortion arises when a non-linearity causes two or more signals to interact. We investigated this distortion mechanism by measurement and listening tests using three models of high-quality loudspeaker. Our aim was to discover whether intermodulation distortion of ultrasonic (i.e., above 20 kHz) signal elements could lead to their detectability and confound listening tests or otherwise modify the listening experience. The paper concludes that while such distortion can be found and must be accounted for in some psychoacoustic threshold experiments, it is not pertinent to playback of current high-resolution recordings.

On the topic of high-performance audio, there remains disagreement over the ways in which sound quality might benefit from higher sample-rates or bit-depths in a digital path. Here we consider the hypothesis that if a digital pathway includes any unintended or undithered quantizations, then several types of errors are imprinted, whose nature will change with increased sampling rate and wordsize. Although dither methods for ameliorating quantization error have been well understood in the literature for some time, these insights are not always applied in practice. We observe that it can be rare for a performance to be captured, produced, and played back with a chain "flawless" in this regard. The paper includes an overview of digital sampling and quantization with additive, subtractive, and noise-shaped dither. The paper also discusses more advanced topics such as cascaded quantizers, fixed and floatingpoint arithmetic, and time-domain aspects of quantization errors. The paper concludes with guidelines and recommendations, including for the design of listening tests. SETTING THE SCENEIn [1] we suggested that "High Resolution" should be considered an attribute of a complete system in the analog domain (from microphone to loudspeaker)-rather than of the distributed signal or a specific technology.If the system includes a digital path, higher sample rates enable wider bandwidth and it has been questioned whether a listening preference for wider-bandwidth systems could result from the reproduction of signal frequencies above 20 kHz, or alternatively, whether it might arise as a side-effect of filtering in the chain, such as may be encountered when constraining bandwidth to meet a Nyquist criterion.In [3] and [4] we introduced a hierarchical method by which high resolution, defined as clear separation of temporal events, can be delivered efficiently. Prior to this there has been a tendency to describe resolution in the digital domain by the proxies of sample rate, bandwidth or data rate. We can't listen to a digital file without first converting it back to analog; this paper continues to consider the entire chain.A third frequency-domain hypothesis suggests that wider-band signals may cause misbehavior in playback systems (shown to be improbable in [5]).A fourth possibility, raised here, is that if a chain has defective quantizations in any part of a digital path, then the resulting errors (manifesting as distortion and/or modulation noise) also change with the inter-related variables of sampling rate and wordsize, with collateral consequences. Outline of This PaperThis paper is both a tutorial and call to action, reminding about some nowadays-overlooked fundamentals.Sec. 1 introduces the topic of modulation noise, a type of system error that can disturb or alter perception of background noise, or spatial or low-frequency elements.Sec. 2 reviews quantization distortion and in Sec. 3 we recap the properties of additive, subtractive, and noise-shaped dither, including maintaining linearity to levels well below the LSB (le...

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This paper takes a pragmatic approach to the design of a task analysis support tool. Instead of proposing a new approach to analysis, it looks at the common requirements for providing support to a wide range of task analysis practitioners, each applying their own style of analysis. The paper describes the range of activities undertaken when practicing what is commonly referred to as "task analysis". It is proposed that users will only tolerate a level of syntactical complexity in a tool that is sufficient to meet their task analysis needs. Further complexity becomes a barrier to use. Hierarchical Task Analysis (HTA) is selected as the method to be supported because it is a widely used, generic approach that is also the basis of a number of more specialized methods. A commercial tool supporting these requirements is described along with the benefits that may be accrued through its use.