There is an odd contradiction about much of the empirical (experimental) literature: The data is analysed using statistical tools which presuppose that there is some noise or randomness in the data, but the source and possible nature of the noise are rarely explicitly discussed. This paper argues that the noise should be brought out into the open, and its nature and implications openly discussed. Whether the statistical analysis involves testing or estimation, the analysis inevitably is built upon some assumed stochastic structure to the noise. Different assumptions justify different analyses, which means that the appropriate type of analysis depends crucially on the stochastic nature of the noise. This paper explores such issues and argues that ignoring the noise can be dangerous.

Noise is a ubiquitous feature for all organisms growing in nature. Noise (defined here as stochastic variation) in the availability of nutrients, water and light profoundly impacts their growth and development. Not only is noise present as an external factor but cellular processes themselves are noisy. Therefore, it is remarkable that organisms can display robust control of growth and development despite noise. To survive, various mechanisms to suppress noise have evolved. However, it is also becoming apparent that noise is not just a nuisance that organisms must suppress but can be beneficial as low noise can facilitate the response of an organism to a sub-threshold input signal in a stochastic resonance mechanism. This review discusses mechanisms capable of noise suppression or noise leveraging that might play a significant role in robust temporal regulation of an organism’s response to their noisy environment.

While nonspeech communication and “metaphorical” silence (in opposition to voice) have benefited from a considerable academic attention, less is known about quiet environments and the intentional practice of silence. We theorize these silences as potential catalysts of internal and collective reflection. Such silences can strongly impact individual and organizational processes and outcomes, notably in the workplace. The meaning, valence, and effects of these silences are highly context- and perspective-dependent. By characterizing and studying these silences and their effects, we show how they are functional or dysfunctional to individuals or organizations. These silences can notably serve as emotion regulators and generate an environment favorable to individual and collective decision making. Examining what is lost by individuals and organizations due to a lack of these silence and what can be gained with a better harnessing of their power is promising.

English morphosyntactic agreement, such as determiner–noun agreement in These cabs broke down and noun–verb agreement in The cabs break down, has a few interesting properties that enable us to investigate whether agreement has a psycholinguistic function, that is, whether it helps the listener process linguistic information expressed by a speaker. The present project relies on these properties in a perception experiment, examines the two aforementioned types of English agreement, and aims at analyzing whether and how native English listeners benefit from agreement. The two types of agreement were contrasted with cases without any overtly agreeing elements (e.g. The cabs broke down). Native speakers of English with normal hearing heard short English sentences in quiet and in more or less intense white noise and were requested to indicate whether the second word of the sentence (e.g. These cabs broke down) was a singular or plural noun. Accuracy was entered as the response variable in the binomial logistic regression model. Results showed that overt determiner–noun agreement clearly increased response accuracy, while noun–verb agreement had at best marginal effects. The findings are interpreted against the background of functional aspects of linguistic structures in English, in the context of unfavorable listening conditions in particular.

Appropriate space allowances for animals are yet to be specifically determined for lairage. Space allowances that may be suitable for animals in lairage are suggested, based on reviewed studies of animals in transport, lairage and on farm. The longer animals are in lairage the more space they require, in order to be able to get up and lie down and lie undisturbed by congeners. Little work has been done on air quality and air flow characteristics in lairages. The range of ventilation must be sufficient to control levels of toxic or irritant gases such as carbon dioxide and ammonia and to remove excess heat and humidity; the latter being particularly relevant for pig lairages in hot weather. Intensities of sound measured in lairages often exceed 85 dB and there is evidence to suggest that such levels can be stressful especially for pigs; and human shouting appears particularly aversive to animals. Cattle vocalise in response to painful stimuli and to convey information to conspecifics that may be related to fear and distress. There is limited evidence that sheep adapt to continuous sound, provided it is not too loud, but respond to intermittent sounds such as gates banging and human shouting. Vocal communication between sheep may be less important than that between cattle and pigs. Levels of vocalisation are potential indices of animal welfare. Animals' prior experiences and factors such as sex, group size and constitution, pen design, and climatic or environmental conditions affect their welfare and responses to conditions in lairage.

Sounds in the laboratory and animal house environment were monitored for sound pressure levels over both low frequency (10Hz-l2.5kHz) and high frequency (12.5—70 kHz) ranges and were recorded for frequency analysis over the range 10Hz-100kHz. Forty sources of sound were investigated at 10 different sites. Sources included environmental control systems, maintenance and husbandry procedures, cleaning equipment and other equipment used near animals. Many of the sounds covered a wide frequency band and extended into the ultrasonic (> 20kHz) range. Sound levels produced by environmental control systems were generally at a low level. High sound pressure levels (SPLs) up to and exceeding 85dB SPL were recorded during cleaning and particularly high levels were recorded from the transport systems studied. Equipment such as a tattoo gun, a condensation extractor system, a high-speed centrifuge, and an ultrasonic disintegrator produced high levels of sound over a broad spectrum.

As many laboratory animals are much more sensitive to a wider range of sound frequency than humans, it seems likely that the levels of sound reported here could adversely affect animals through physiological or behavioural changes, or may even cause sensory damage in extreme cases. There appear to have been no studies on the minimal threshold levels for such adverse responses, or on the long-term effects of exposure to the types of sounds recorded here. It is not yet possible to set realistic exposure limits for laboratory animals.

A collaborative effort was undertaken to delineate underwater noise levels within holding enclosures at marine mammal facilities. Ambient noise levels were measured under normal operating conditions in the enclosures of 14 participating facilities. Facility habitats varied from ocean environments to fully enclosed pools. The means and standard errors of the noise pressure spectral densities measured across all pools were similar to those measured in natural coastal environments with relatively low presence of anthropogenic noise. Highest levels of noise in land-based pools were generally at frequencies < 2 kHz and primarily due to the operation of water treatment/filtration systems. Noise levels in land-based pools were comparable to or lower than semi-natural and natural systems at higher frequencies because of the presence of biological noise sources in these systems (eg snapping shrimp [Alpheus spp]). For odontocete enclosures, the whales themselves were often the greatest source of sound at frequencies where the whales have their best hearing (~40-100 kHz). The potential for facility ambient noise to acoustically mask odontocete communication signals and echolocation clicks appears to be low. In general, when noise was elevated it was at frequencies outside the typical frequency ranges of whistles and echolocation clicks, and where odontocetes have poor hearing sensitivity. Occasional noise issues were found; it is therefore recommended that facilities periodically assess enclosure noise conditions to optimise animal management and welfare.

This study assessed how sound affected fear- and maintenance-related behaviour in singly housed cats (Felis silvestris catus) in an animal shelter. Two daily 30-min observation sessions (morning and evening) were made for 98 cats from admittance for ten days or until the cat was removed. Cat behaviour and presence of sound (classified by the source) were recorded by instantaneous and one-zero sampling with 15-s intervals. Each 30-min observation session was classified as ‘quiet’ or ‘noisy’ if the one-zero score for presence of sound was above or below the median of sessions at that time of day. To ensure that cats had at least two complete days of comparable observations, statistical analysis was restricted to the 70 cats (30 females, 40 males) present for two or more weekdays. Cats varied widely in the amount of fear and maintenance behaviour they performed. Males showed less fear and maintenance behaviour than females. Morning sessions consistently had much more sound than evenings, and cats showed more fear behaviour and less maintenance behaviour in the mornings. Cats showed more fear behaviour in noisy morning sessions than quiet ones, with no comparable difference in maintenance behaviour. Where sessions included a pronounced transition in sound, fear-related behaviour was more common after a transition from quiet to noisy and less common after a transition from noisy to quiet The results show that shelter cats vary greatly in their responses and suggest that sound in shelter environments can substantially affect their behaviour. Lowering sound levels in shelters may help improve cat welfare.

Recent work has derived the optimal policy for two-alternative value-baseddecisions, in which decision-makers compare the subjective expected reward oftwo alternatives. Under specific task assumptions — such as linearutility, linear cost of time and constant processing noise — the optimalpolicy is implemented by a diffusion process in which parallel decisionthresholds collapse over time as a function of prior knowledge about averagereward across trials. This policy predicts that the decision dynamics of eachtrial are dominated by the difference in value between alternatives and areinsensitive to the magnitude of the alternatives (i.e., their summed values).This prediction clashes with empirical evidence showing magnitude-sensitivityeven in the case of equal alternatives, and with ecologically plausible accountsof decision making. Previous work has shown that relaxing assumptions aboutlinear utility or linear time cost can give rise to optimal magnitude-sensitivepolicies. Here we question the assumption of constant processing noise, infavour of input-dependent noise. The neurally plausible assumption ofinput-dependent noise during evidence accumulation has received strong supportfrom previous experimental and modelling work. We show that includinginput-dependent noise in the evidence accumulation process results in amagnitude-sensitive optimal policy for value-based decision-making, even in thecase of a linear utility function and a linear cost of time, for both single(i.e., isolated) choices and sequences of choices in which decision-makersmaximise reward rate. Compared to explanations that rely on non-linear utilityfunctions and/or non-linear cost of time, our proposed account ofmagnitude-sensitive optimal decision-making provides a parsimonious explanationthat bridges the gap between various task assumptions and between various typesof decision making.