The potential impact of literacy intervention on speech sound production in students with intellectual disability and communication difficulties.

A small body of research and reports from educational and clinical practice suggest that teaching literacy skills may facilitate the development of speech sound production in students with intellectual disabilities (ID). However, intervention research is needed to test the potential connection. This study aimed to investigate whether twelve weeks of systematic, digital literacy intervention enhanced speech sound production in students with ID and communication difficulties. A sample of 121 students with ID were assigned to four different groups: phonics-based, comprehension-based, a combination with both phonics- and comprehension-based intervention and a comparison group with teaching-as-usual. Speech sound production was assessed before and after the intervention. The results on the data without the imputed variable suggested a significant positive effect of systematic, digital literacy interventions on speech sound production. However, results from sensitivity analyses with imputed missing data was more ambiguous, with the effect only approaching significance (ps = .05-.07) for one of the interventions. Nonetheless, we tentatively suggest that systematic, digital literacy intervention could support speech development in students with ID and communication difficulties. Future research should be done to confirm and further elucidate the functional mechanisms of this link, so that we may have a better understanding and can improve instruction and the pivotal abilities of speech and reading.

Gekko gecko as a model organism for understanding aspects of laryngeal vocal evolution.

The ability to communicate through vocalization plays a key role in the survival of animals across all vertebrate groups. While avian reptiles have received much attention relating to their stunning sound repertoire, non-avian reptiles have been wrongfully assumed to have less elaborate vocalization types and little is known about the biomechanics of sound production and their underlying neural pathways. We investigated alarm calls of Gekko gecko using audio and cineradiographic recordings of their alarm calls. Acoustic analysis revealed three distinct call types: a sinusoidal call type (type 1), a train-like call type, characterized by distinct pulse trains (type 3), and an intermediary type, which showed both sinusoidal and pulse train components (type 2). Kinematic analysis of cineradiographic recordings showed that laryngeal movements differ significantly between respiratory and vocal behavior: during respiration, animals repeatedly moved their jaws to partially open their mouths, which was accompanied by small glottal movements. During vocalization, the glottis was pulled back, contrasting with what has previously been reported. In-vitro retrograde tracing of the nerve innervating the laryngeal constrictor and dilator muscles revealed round to fusiform motoneurons in the hindbrain-spinal cord transition ipsilateral to the labeled nerve. Taken together, our observations provide insight into the alarm calls generated by G. gecko, the biomechanics of this sound generation and the underlying organization of motoneurons involved in the generation of vocalizations. Our observations suggest that G. gecko may be an excellent non-avian reptile model organism for enhancing our understanding of the evolution of vertebrate vocalization.

The potential of acoustic monitoring of aquatic insects for freshwater assessment.

Aquatic insects are a major indicator used to assess ecological condition in freshwater environments. However, current methods to collect and identify aquatic insects require advanced taxonomic expertise and rely on invasive techniques that lack spatio-temporal replication. Passive acoustic monitoring (PAM) is emerging as a non-invasive complementary sampling method allowing broad spatio-temporal and taxonomic coverage. The application of PAM in freshwater ecosystems has already proved useful, revealing unexpected acoustic diversity produced by fishes, amphibians, submerged aquatic plants, and aquatic insects. However, the identity of species producing sounds remains largely unknown. Among them, aquatic insects appear to be the major contributor to freshwater soundscapes. Here, we estimate the potential number of soniferous aquatic insects worldwide using data from the Global Biodiversity Information Facility. We found that four aquatic insect orders produce sounds totalling over 7000 species. This number is probably underestimated owing to poor knowledge of aquatic insects bioacoustics. We then assess the value of sound producing aquatic insects to evaluate ecological condition and find that they might be useful despite having similar responses in pristine and degraded environments in some cases. Both expert and automated identifications will be necessary to build international reference libraries and to conduct acoustic bioassessment in freshwaters. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

The domestication of the larynx: The neural crest connection.

Wolves howl and dogs bark, both are able to produce variants of either vocalization, but we see a distinct difference in usage between wild and domesticate. Other domesticates also show distinct changes to their vocal output: domestic cats retain meows, a distinctly subadult trait in wildcats. Such differences in acoustic output are well-known, but the causal mechanisms remain little-studied. Potential links between domestication and vocal output are intriguing for multiple reasons, and offer a unique opportunity to explore a prominent hypothesis in domestication research: the neural crest/domestication syndrome hypothesis. This hypothesis suggests that in the early stages of domestication, selection for tame individuals decreased neural crest cell (NCCs) proliferation and migration, which led to a downregulation of the sympathetic arousal system, and hence reduced fear and reactive aggression. NCCs are a transitory stem cell population crucial during embryonic development that tie to diverse tissue types and organ systems. One of these neural-crest derived systems is the larynx, the main vocal source in mammals. We argue that this connection between NCCs and the larynx provides a powerful test of the predictions of the neural crest/domestication syndrome hypothesis, discriminating its predictions from those of other current hypotheses concerning domestication.

Characterization of sound production by the pot-bellied seahorse (Hippocampus abdominalis) during feeding.

Sound production during feeding by the pot-bellied seahorse, Hippocampus abdominalis, was quantified with an observation of clicks (acoustic signal) and snicks (visual behavior). Female, male, and juvenile seahorses had feeding sounds characterized for peak (dominant) frequency (Hz), sound pressure level (SPL), and duration (ms). Subject body size and condition was estimated by standard length (SL, cm), to determine an estimate of body condition index (BCI). An inverse correlation between mean peak frequency (Hz) of clicks and SL was found for females. A negative correlation between peak frequency (Hz) of clicks and a residual BCI was determined for both males and females, suggesting that acoustic signals may contain information regarding fitness.

Ultrafast sound production mechanism in one of the smallest vertebrates.

Motion is the basis of nearly all animal behavior. Evolution has led to some extraordinary specializations of propulsion mechanisms among invertebrates, including the mandibles of the dracula ant and the claw of the pistol shrimp. In contrast, vertebrate skeletal movement is considered to be limited by the speed of muscle, saturating around 250 Hz. Here, we describe the unique propulsion mechanism by which Danionella cerebrum, a miniature cyprinid fish of only 12 mm length, produces high amplitude sounds exceeding 140 dB (re. 1 µPa, at a distance of one body length). Using a combination of high-speed video, micro-computed tomography (micro-CT), RNA profiling, and finite difference simulations, we found that D. cerebrum employ a unique sound production mechanism that involves a drumming cartilage, a specialized rib, and a dedicated muscle adapted for low fatigue. This apparatus accelerates the drumming cartilage at over 2,000 g, shooting it at the swim bladder to generate a rapid, loud pulse. These pulses are chained together to make calls with either bilaterally alternating or unilateral muscle contractions. D. cerebrum use this remarkable mechanism for acoustic communication with conspecifics.

Functional plasticity of the swim bladder as an acoustic organ for communication in a vocal fish.

Teleost fishes have evolved a number of sound-producing mechanisms, including vibrations of the swim bladder. In addition to sound production, the swim bladder also aids in sound reception. While the production and reception of sound by the swim bladder has been described separately in fishes, the extent to which it operates for both in a single species is unknown. Here, using morphological, electrophysiological and modelling approaches, we show that the swim bladder of male plainfin midshipman fish (Porichthys notatus) exhibits reproductive state-dependent changes in morphology and function for sound production and reception. Non-reproductive males possess rostral 'horn-like' swim bladder extensions that enhance low-frequency (less than 800 Hz) sound pressure sensitivity by decreasing the distance between the swim bladder and inner ear, thus enabling pressure-induced swim bladder vibrations to be transduced to the inner ear. By contrast, reproductive males display enlarged swim bladder sonic muscles that enable the production of advertisement calls but also alter swim bladder morphology and increase the swim bladder to inner ear distance, effectively reducing sound pressure sensitivity. Taken together, we show that the swim bladder exhibits a seasonal functional plasticity that allows it to effectively mediate both the production and reception of sound in a vocal teleost fish.

The ground offers acoustic efficiency gains for crickets and other calling animals.

Male crickets attract females by producing calls with their forewings. Louder calls travel further and are more effective at attracting mates. However, crickets are much smaller than the wavelength of their call, and this limits their power output. A small group called tree crickets make acoustic tools called baffles which reduce acoustic short-circuiting, a source of dipole inefficiency. Here, we ask why baffling is uncommon among crickets. We hypothesize that baffling may be rare because like other tools they offer insufficient advantage for most species. To test this, we modelled the calling efficiencies of crickets within the full space of possible natural wing sizes and call frequencies, in multiple acoustic environments. We then generated efficiency landscapes, within which we plotted 112 cricket species across 7 phylogenetic clades. We found that all sampled crickets, in all conditions, could gain efficiency from tool use. Surprisingly, we also found that calling from the ground significantly increased efficiency, with or without a baffle, by as much as an order of magnitude. We found that the ground provides some reduction of acoustic short-circuiting but also halves the air volume within which sound is radiated. It simultaneously reflects sound upwards, allowing recapture of a significant amount of acoustic energy through constructive interference. Thus, using the ground as a reflective baffle is an effective strategy for increasing calling efficiency. Indeed, theory suggests that this increase in efficiency is accessible not just to crickets but to all acoustically communicating animals whether they are dipole or monopole sound sources.

Effects of temperature on acoustic and visual courtship and reproductive success in the two-spotted goby Pomatoschistus flavescens.

Fish are ectothermic and small changes in water temperature could greatly affect reproduction. The two-spotted goby is a small semi-pelagic species that uses visual and acoustic displays to mate. Here, we studied the effect of temperature (16 and 20 °C) on acoustic and visual courtship and associated reproductive success in 39 males. Temperature influenced male visual courtship performed outside the nest, but it did not influence calling rate and the number of laid eggs. Interestingly, the number of sounds (drums) was the sole predictor of spawning success. These findings suggest that exposure to different temperatures within the species' natural range affect courtship behaviour but not its reproductive success. We propose that finding the link between acoustic behaviour and reproduction in fishes offers the opportunity to monitor fish sounds both in the lab and in nature to learn how they respond to environmental changes and human impacts, namely global warming.

Form function of sulcus acusticus of the sagittal otolith in seven Sciaenidae (Acanthuriformes) species using geometric morphometrics (southwestern Atlantic).

The morphology of otoliths determines the function they perform, and it is influenced by genetic and environmental factors. Knowing those relationships is necessary to understand the role of hearing in fish. The objectives of this work were: exploring the shape of the sulcus of the sagittal otolith in seven species of Sciaenidae, in relation to sound production, and analyzing whether the shape and size of the sulcus can be used as a phylogenetic character. For this purpose, geometric morphometry analysis was carried out using landmarks data. It was found that there is an influence of size on the shape of the sulcus, and significant differences were found between the shapes of the sulcus (permutational multivariate analysis of variance). Three general shapes of the sulcus were identified (using principal component analysis, canonical variate analysis, and clustering): (1) in species that produce sounds at dominant frequencies <350 Hz, the deformation of the sulcus showed a tendency towards circularity of the ostium; (2) in those species that produce sounds at frequencies >350 Hz, the ostium showed a flattened ovoid shape, and the cauda increased its length; (3) the species that do not produce sounds, did not show any modifications, relative to the form of consensus. Despite finding sister species that presented similar sulcus shapes in the phylogeny, the results did not confirm that this can be used as a phylogenetic character. This work discusses whether the combined effects of phylogenetic legacy and natural functional selection have led to convergent evolution for the sulcus form. The differences presented by the sulcus of species that occupy the same clade, could indicate that there is a displacement of characters. The sagittal otolith and the sensory macula associated with the sulcus acusticus are highly plastic structures that are subject to strong evolutionary pressure in relation to environmental and behavioral factors, resulting in great variability in shapes that can be associated with a specific character. The variation in the shape of the sulcus would allow the analysed species to coexist in the same coastal soundscapes, without losing their particular hearing needs, even in case of overlapping their spatial and temporal distribution areas.

Sound detection and production mechanisms in aquatic decapod and stomatopod crustaceans.

The sensory systems of crustaceans (aquatic decapods and stomatopods) have adapted to a diverse range of aquatic ecosystems. Sound production in aquatic crustaceans is more widespread than previously thought, and has been shown to play a major role in many of their life-history strategies; however, there are still many gaps in our understanding of their sound reception abilities. Crustaceans have three main sensory receptors for sound - the statocyst, superficial hair cells and chordotonal organs - which are all sensitive to the particle motion component of the sound field, rather than the pressure component. Our current understanding of these receptors is that they are sensitive to low-frequency sounds (<2000 Hz). There are a wide variety of sound-producing mechanisms employed by these animals, ranging from stridulation to implosive cavitation (see Glossary). These signals are used for a range of social behaviours, such as courtship, territorial defence and assessing 'resource guarding'. Furthermore, there are examples of sound signals that exceed their hearing range, highlighting a mismatch in our understanding of their hearing systems. This mismatch provides weight to the suggestion that another sound transmission channel - substrate-borne vibrations - might be at play, particularly because most crustaceans live on or near the seafloor. Finally, suggestions are made regarding potential future work that is needed to fill the substantial gaps in our understanding of how crustaceans hear and produce sound.

Detection of invasive fish species with passive acoustics: Discriminating between native and non-indigenous sciaenids.

Invasive alien species have been rising exponentially in the last decades impacting biodiversity and ecosystem functioning. The soniferous weakfish, Cynoscion regalis, is a recent invasive sciaenid species in the Iberian Peninsula and was first reported in the Tagus estuary in 2015. There is concern about its possible impacts on native species, namely the confamiliar meagre, Argyrosomus regius, as there is overlap in their feeding regime, habitat use, and breeding behaviour. Here, we characterised the sciaenid-like sounds recently recorded in the Tagus estuary and showed that they are made by weakfish as they have similar numbers of pulses and pulse periods to the sounds made by captive breeding weakfish. We further demonstrate that breeding grunts from weakfish and the native sciaenid, recorded either in captivity or Tagus estuary, differ markedly in sound duration, number of pulses and pulse period in the two species, but overlap in their spectral features. Importantly, these differences are easily detected through visual and aural inspections of the recordings, making acoustic recognition easy even for the non-trained person. We propose that passive acoustic monitoring can be a cost-effective tool for in situ mapping of weakfish outside its natural distribution and an invaluable tool for early detection and to monitor its expansion.

Speech sound production, speech intelligibility, and oral-motor outcomes of preterm children: Are they different from full term children?

We studied the speech sound abilities of preterm (PT) children. Thirty-one PT and twenty-nine full term (FT) children were recruited. Speech abilities were assessed in single word, story retelling, oral-motor, and intelligibility. PT group had poorer outcomes (Mean = 25.77, SD = 17.19) than FT ones (Mean = 5.9, SD = 4.97) for single word (p < 0.001). They obtained poorer results (Mean = 9.65, SD = 7.85) than FT peers (Mean = 2.95, SD = 3.34) in story retelling (p = 0.002) and intelligibility (Man-Whitney U = 89.50, p = 0.02). They obtained lower values for diadochokesis/patuku/(p < 0.001), isolated (p = 0.001), and sequenced movements (p = 0.02) but not for diadochokesis/patukejk/(p = 0.12). Significant values of correlation were found among single word scores with birth weight (r = -.54, p < .001) and gestational age (r = -0.67, p < .001) and story retelling scores with birth weight (r = -0.40, p = .013) and gestational age (r = -0.64, p < .001). The associations of single word score and maternal (r = -0.02, p = .85) and paternal education (r = -0.10, p = .41) were not significant. No significant relationships were obtained between story retelling score and maternal (r = 0.16, p = .34) and paternal education (r = 0.09, p = .59). The significant values were obtained for associations of intelligibility with isolated (r = 0.54, p = .001), sequenced movements (r = 0.59, p < .001), and diadochokesis/patukejk/(r = 0.39, p = .016) but not significant for intelligibility and diadochokesis/patuku/(r = 0.25, p = .13). Findings implied that speech abilities are weaker in PT children.

Experimental characterization and automatic identification of stridulatory sounds inside wood.

The propagation of animal vocalizations in water and in air is a well-studied phenomenon, but sound produced by bark and wood-boring insects, which feed and reproduce inside trees, is poorly understood. Often being confined to the dark and chemically saturated habitat of wood, many bark- and woodborers have developed stridulatory mechanisms to communicate acoustically. Despite their ecological and economic importance and the unusual medium used for acoustic communication, very little is known about sound production in these insects, or their acoustic interactions inside trees. Here, we use bark beetles (Scolytinae) as a model system to study the effects of wooden tissue on the propagation of insect stridulations and propose algorithms for their automatic identification. We characterize distance dependence of the spectral parameters of stridulatory sounds, propose data-based models for the power decay of the stridulations in both outer and inner bark, provide optimal spectral ranges for stridulation detectability and develop automatic methods for their detection and identification. We also discuss the acoustic discernibility of species cohabitating the same log. The species tested can be acoustically identified with 99% of accuracy at distances up to 20 cm and detected to the greatest extent in the 2-6 kHz frequency band. Phloem was a better medium for sound transmission than bark.

Sound Visualization Demonstrates Velopharyngeal Coupling and Complex Spectral Variability in Asian Elephants.

Sound production mechanisms set the parameter space available for transmitting biologically relevant information in vocal signals. Low-frequency rumbles play a crucial role in coordinating social interactions in elephants' complex fission-fusion societies. By emitting rumbles through either the oral or the three-times longer nasal vocal tract, African elephants alter their spectral shape significantly. In this study, we used an acoustic camera to visualize the sound emission of rumbles in Asian elephants, which have received far less research attention than African elephants. We recorded nine adult captive females and analyzed the spectral parameters of 203 calls, including vocal tract resonances (formants). We found that the majority of rumbles (64%) were nasally emitted, 21% orally, and 13% simultaneously through the mouth and trunk, demonstrating velopharyngeal coupling. Some of the rumbles were combined with orally emitted roars. The nasal rumbles concentrated most spectral energy in lower frequencies exhibiting two formants, whereas the oral and mixed rumbles contained higher formants, higher spectral energy concentrations and were louder. The roars were the loudest, highest and broadest in frequency. This study is the first to demonstrate velopharyngeal coupling in a non-human animal. Our findings provide a foundation for future research into the adaptive functions of the elephant acoustic variability for information coding, localizability or sound transmission, as well as vocal flexibility across species.

Acoustic and postural displays in a miniature and transparent teleost fish, Danionella dracula.

Acoustic behavior is widespread across vertebrates, including fishes. We report robust acoustic displays during aggressive interactions for a laboratory colony of Danionella dracula, a miniature and transparent species of teleost fish closely related to zebrafish (Danio rerio), which are hypothesized to be sonic based on the presence of a hypertrophied muscle associated with the male swim bladder. Males produce bursts of pulsatile sounds and a distinct postural display - extension of a hypertrophied lower jaw, a morphological trait not present in other Danionella species - during aggressive but not courtship interactions. Females show no evidence of sound production or jaw extension in such contexts. Novel pairs of size-matched or -mismatched males were combined in resident-intruder assays where sound production and jaw extension could be linked to individuals. In both dyad contexts, resident males produced significantly more sound pulses than intruders. During heightened sonic activity, the majority of the highest sound producers also showed increased jaw extension. Residents extended their jaw more than intruders in size-matched but not -mismatched contexts. Larger males in size-mismatched dyads produced more sounds and jaw extensions compared with their smaller counterparts, and sounds and jaw extensions increased with increasing absolute body size. These studies establish D. dracula as a sonic species that modulates putatively acoustic and postural displays during aggressive interactions based on residency and body size, providing a foundation for further investigating the role of multimodal displays in a new model clade for neurogenomic and neuroimaging studies of aggression, courtship and other social interactions.

Signature whistles exhibit a 'fade-in' and then 'fade-out' pattern of relative amplitude declination.

Bottlenose dolphins have individually distinct signature whistles that are characterized by a stereotyped frequency-time contour. Signature whistles are commonly exchanged with short time delays between calls. Dolphin whistles are produced by pressurized nasal sacs that increase and then decrease in pressure over emission. This study found that the relative amplitude modulation pattern over time exhibited the same fade-in and then fade-out pattern in the signature whistles of eight bottlenose dolphins at the Navy in San Diego, CA. Both the initial and final five percent of the whistle's duration also had significantly lower mean relative amplitude than the center five percent. The current analyses of the amplitude-time relationship was then integrated to a previously reported model of the negative relationship between relative log amplitude and log peak frequency. This produced a more robust model for accounting for the predictable aspects of the more broadly non-stereotyped amplitude modulations of signature whistles. Whether dolphins can intentionally manipulate these amplitude features or they are simple by-products of the sound production system, and further whether they are perceived and utilized by receivers, is an exciting area for continued research.

The mechanics of acoustic signal evolution in field crickets.

Field crickets (Family Gryllidae, Subfamily Gryllinae) typically produce tonal calls with carrier frequencies in the range 3-8 kHz. In this study, we explored the use of a finite element model (FEM) of the stridulatory apparatus of a field cricket, Gryllus bimaculatus, based on experimental measurements of resonator geometry and mechanical properties, to predict the measured call carrier frequencies of eight other field cricket species, ranging between 3 and 7 kHz. The model allowed accurate predictions of carrier frequencies for all eight species to within a few hundred hertz from morphological measurements of their resonators. We then used the model to explore the plausible evolutionary design space for field cricket call carrier frequency along the axes of resonator size and thickness, and mapped the locations of the nine experimentally measured species in this design space. Although the nine species spanned the evolutionarily conserved spectrum of carrier frequency and body size in field crickets, they were clustered in a small region of the available design space. We then explored the reasons for this apparent evolutionary constraint on field cricket carrier frequencies at both the lower and higher limit. We found that body size and sound radiation efficiency were the main constraints at the lower limits, whereas the energetics of stridulation using the clockwork mechanism may pose a constraint at higher frequencies.

Vortex Formation Times in the Glottal Jet, Measured in a Scaled-Up Model.

In this paper, the timing of vortex formation on the glottal jet is studied using previously published velocity measurements of flow through a scaled-up model of the human vocal folds. The relative timing of the pulsatile glottal jet and the instability vortices are acoustically important since they determine the harmonic and broadband content of the voice signal. Glottis exit jet velocity time series were extracted from time-resolved planar DPIV measurements. These measurements were acquired at four glottal flow speeds (u SS = 16.1-38 cm/s) and four glottis open times (T o = 5.67-23.7 s), providing a Reynolds number range Re = 4100-9700 and reduced vibration frequency f* = 0.01-0.06. Exit velocity waveforms showed temporal behavior on two time scales, one that correlates to the period of vibration and another characterized by short, sharp velocity peaks (which correlate to the passage of instability vortices through the glottis exit plane). The vortex formation time, estimated by computing the time difference between subsequent peaks, was shown to be not well-correlated from one vibration cycle to the next. The principal finding is that vortex formation time depends not only on cycle phase, but varies strongly with reduced frequency of vibration. In all cases, a strong high-frequency burst of vortex motion occurs near the end of the cycle, consistent with perceptual studies using synthesized speech.