Dominant Cue Research Articles

Relative cue precision and prior knowledge contribute to the preference of proximal and distal landmarks in human orientation

A prevailing argument posits that distal landmarks dominate over proximal landmarks as orientation cues. However, no studies have tested this argument or examined the underlying mechanisms. This project aimed to close this gap by examining the roles of relative cue precision and prior knowledge in cue preference. Participants learned object locations with proximal and distal landmarks in an immersive virtual environment. After walking a path without seeing objects or landmarks, participants disoriented themselves by spinning in place and pointed to the objects with the reappearance of a proximal landmark being rotated −50°, a distal landmark being rotated 50°, or both (Conflict). Heading errors were examined. Experiment 1 manipulated the relative cue precision. Results showed that in Conflict condition, the observed weight on the distal cue (exceeding 0.5) changed with but remained higher than the weight predicted by the relative cue precision. This indicates that besides the relative cue precision, prior knowledge of distal cue dominance also influences orientation cue usage. In Experiments 2 and 3, participants walked a path stopping at one object location. Participants were informed of it explicitly in Experiment 2 but not in Experiment 3. Results showed that distal cue dominance still occurred in Experiment 3. However, in Experiment 2, proximal cue dominance appeared, and it was not predicted by the relative cue precision. These results suggest that prior knowledge of proximal cue dominance might have been invoked by the instruction of locations. Consistent with the Bayesian inference model, human cue usage in orientation is determined by relative cue precision and prior knowledge. The choice of prior knowledge can be influenced by instructions.

Cue transparency leads to a myopic decision habit: Optimal training ratios to avoid overshadowing

Environmental cues to optimal decisions abound. Some are highly predictive and immediately transparent (e.g., amounts) whereas others may either be harder to discern or take time to obtain (e.g., probability and delay). In the present experiment, we manipulated the availability of a particularly salient, and thus dominant, cue regarding when a participant should cash-in when an outcome’s value is increasing over time – a target cube’s size grew as its value grew. For some targets, this expanding cube cue was visible but for others it was not. In contrast, a highly predictive but less obviously relevant color cue was omnipresent, and the recent delay-reward relationship also signaled the reward dynamics. The research addressed a simple question: would more training with transparent targets that reveal the dominant cue produce greater sensitivity to a changing contingency or would more training with opaque targets produce greater sensitivity? Participants’ contingency sensitivity benefitted more when the majority of the training involved opaque targets. Although extensive training with transparent targets produced a strong understanding of reward dynamics, this dominant decision cue undermined attention to secondary cues that are more important in less transparent environments.

Perception of emotional music by children with cochlear implants reveals developmental plasticity

Cochlear implants provide poor access to the frequency components needed to accurately identify emotional music and speech. Nonetheless, a series of studies revealed that children with cochlear implants develop unique strategies to identify emotion in music. Although musical changes were difficult for them to detect, children with cochlear implants responded most accurately to rhythmic changes and also relied mainly on temporal information to judge whether music was happy or sad. By contrast, mode (frequency) information dominated perception of musical emotion in typically developing children and was used more clearly by bimodal device users (cochlear implant in one ear with acoustic hearing in the other) than children with bilateral deafness using unilateral or bilateral cochlear implants. Mode became the more dominant cue with increasing residual hearing in the non-implanted ear. Children with unilateral cochlear implants showed prolonged response times relative to a control group of normal hearing peers while judging whether music was happy or sad. Response times in children with bimodal devices and bilateral cochlear implants were more similar to controls. Together, these results demonstrate development of novel strategies for music listening and perception of emotion in music based on available cues in children with cochlear implants and suggest that these strategies require cognitive resource.

Seaward Migration and Larval Release Coincide with Lunar and Light-dark Cycles in Supratidal Land Crabs Cardisoma carnifex and Epigrapsus notatus.

Herein we investigated the synchronous breeding migration and larval release of ovigerous females in two dominant supratidal land crabs Cardisoma carnifex and Epigrapsus notatus in the mixed semidiurnal tidal regime in Taijiang National Park (Tainan, Taiwan). We mainly focused on the monthly and daily rhythms during the breeding season of migration and larval release for these two crabs. We also sought to understand what the main environmental cues were for these monthly and diel rhythms. Both lunar and tidal amplitude cycles are potential proximate causes for the monthly lunar/semilunar reproductive rhythm in crabs. Likewise, either the 24-hour (diel) light cycle or tidal cycle can act as the proximate cause for diel reproduction rhythm, and we investigated which one was the main factor that entrains the diel rhythm for these two species. We found that the season of migration and larval release in C. carnifex occured mainly between June and September during the rainy season while those of E. notatus occurred mainly between September and October, near the end of the rainy season. Regarding the rhythm of migration and larval release in monthly time scale, C. carnifex exhibited a semilunar rhythm following the syzygies and E. notatus exhibited a lunar rhythm following the full moon. However, these rhythms did not occur with the maximum amplitude nocturnal and diurnal high tides. This implies that the lunar cycle is a more important environmental cue than the tidal amplitude in the entrainment of the synchronous monthly breeding rhythm for these two species. This pattern is different from other intertidal crabs, most of which use the tidal amplitude cycle as the main environmental cue for larval release. In addition to Chiromantes haematocheir (a supratidal crab), our study provided two more species that live in the supratidal zone time their reproduction with respect to the lunar light cycle and independent of the tide amplitude cycles. For the diel rhythm, both species migrated to the shore and released larvae in the first half of the night during the flood tide. This suggests that the diel light cycle is a dominant cue for the determination of larval release timing for these two species. Larval release does not track the high slack tides, since larvae are only released during the first half of the night and these high slack tides occur only after midnight (0000-0600H) during the days of larval release for these two crab species.

Information signals and bias in investment decisions: A meta-analytic comparison of prediction and actual performance of new ventures

This study investigates the presence, direction, and scale of bias in investors’ consideration of qualitative information signals while appraising new venture proposals through a meta-analysis of 75 empirical studies published between 2000 and 2020. Our results suggest that investors evaluate different information signals differently owing to their varying abilities and motivations. High levels of ability and motivation stimulate elaboration, resulting in positive bias, whereas low levels of both ability and motivation reduce the likelihood of elaboration, resulting in negative bias. However, for lower levels of either ability or motivation, we found a mix of both positive and negative biases determined by the dominance of information cues. While considering the prospects of investment decisions, our results show that signals suggesting growth potential are preferred over those suggesting financial risk coverage. This study has substantial implications for investors to optimize their decision-making processes and enable entrepreneurs to understand investors’ appraisal processes.

Resetting the circadian clock of Alzheimer's mice via GLP-1 injection combined with time-restricted feeding.

Circadian rhythm disturbances are the most common symptoms during the early onset of AD. Circadian rhythm disorders aggravate the deposition of amyloid plaques in the brains of AD patients. Therefore, improving the circadian rhythm of AD patients might slow down the pathological development of neurodegeneration. Circadian regulation is driven by a master clock in suprachiasmatic nuclei (SCN) and peripheral clock located in peripheral organs. The rhythmic feeding–fasting cycle has been proved to dominant cue to entrain peripheral clocks. We hypothesized that dietary intervention to a certain period of time during the dark phase might entrain the clock and reset the disrupted daily rhythms of AD mice. In this study, exogenous glucagon-like peptide-1 (GLP-1) treatment, time-restricted feeding (TRF), and the combination were used to examine the effect of overall circadian rhythm and neurodegenerative pathogenesis of transgenic AD mice. It was confirmed that GLP-1 administration together with time-restricted feeding improves circadian rhythm of 5 × FAD mice including the physiological rhythm of the activity–rest cycle, feeding–fasting cycle, core body temperature, and hormone secretion. Furthermore, GLP-1 and TRF treatments improved the diurnal metabolic homeostasis, spatial cognition, and learning of 5 × FAD mice. The aberrant expression of clock genes, including Baml1, Clock, and Dbp, was improved in the hypothalamus, and pathological changes in neurodegeneration and neuroinflammation were also observed in AD mice with dual treatment.

The Anatomy of Viral Advertising: A Content Analysis of Viral Advertising from the Elaboration Likelihood Model Perspective

This study is a quantitative content analysis of 445 viral video ads shared online between 2009 and 2019. Using the framework of the Elaboration Likelihood Model (ELM) that distinguishes between peripheral and central ad cues, our findings highlight the dominance of peripheral cues over central cues. Viral ads included more emotional than rational appeals and integrated music and sound effects, while the use of substantial arguments was kept to a minimum. The dominance of peripheral cues was also evident across product categories; however, they mainly characterized ads for technology products. Our findings provide more than a mere description of the characteristics of viral ads, but detail the dominant creative elements that viral ads feature, which might infer the effectiveness of specific message elements in driving ad sharing. The theoretical and managerial implications of this study are also discussed.

Cochlear tuning and the peripheral representation of harmonic sounds in mammals.

Albert Feng was a prominent comparative neurophysiologist whose research provided numerous contributions towards understanding how the spectral and temporal characteristics of vocalizations underlie sound communication in frogs and bats. The present study is dedicated to Al's memory and compares the spectral and temporal representations of stochastic, complex sounds which underlie the perception of pitch strength in humans and chinchillas. Specifically, the pitch strengths of these stochastic sounds differ between humans and chinchillas, suggesting that humans and chinchillas may be using different cues. Outputs of auditory filterbank models based on human and chinchilla cochlear tuning were examined. Excitation patterns of harmonics are enhanced in humans as compared with chinchillas. In contrast, summary correlograms are degraded in humans as compared with chinchillas. Comparing summary correlograms and excitation patterns with corresponding behavioral data on pitch strength suggests that the dominant cue for pitch strength in humans is spectral (i.e., harmonic) structure, whereas the dominant cue for chinchillas is temporal (i.e., envelope) structure. The results support arguments that the broader cochlear tuning in non-human mammals emphasizes temporal cues for pitch perception, whereas the sharper cochlear tuning in humans emphasizes spectral cues.

A cross-taxonomic perspective on the integration of temperature cues in vertebrate seasonal neuroendocrine pathways

The regulation of seasonality has been an area of interest for decades, yet global climate change has created extra urgency in the quest to understand how sensory circuits and neuroendocrine control systems interact to generate flexibility in biological timekeeping. The capacity of temperature to alter endogenous or photoperiod-regulated neuroendocrine mechanisms driving seasonality, either as a direct cue or through temperature-dependent effects on energy and metabolism, is at the heart of this phenological flexibility. However, until relatively recently, little research had been done on the integration of temperature information in canonical seasonal neuroendocrine pathways, particularly in vertebrates. We review recent advances from research in vertebrates that deepens our understanding of how temperature cues are perceived and integrated into seasonal hypothalamic thyroid hormone (TH) signaling, which is a critical regulator of downstream seasonal phenotypic changes such as those regulated by the BPG (brain-pituitary-gonadal) axis. Temperature perception occurs through cutaneous transient receptor potential (TRP) neurons, though sensitivity of these neurons varies markedly across taxa. Although photoperiod is the dominant cue used to trigger seasonal physiology or entrain circannual clocks, across birds, mammals, fish, reptiles and amphibians, seasonality appears to be temperature sensitive and in at least some cases this appears to be related to phylogenetically conserved TH signaling in the hypothalamus. Nevertheless, the exact mechanisms through which temperature modulates seasonal neuroendocrine pathways remains poorly understood.

Chickens have excellent sound localization ability.

The mechanisms of sound localization are actively debated, especially which cues are predominately used and why. Our study provides behavioural data in chickens (Gallus gallus) and relates these to estimates of the perceived physical cues. Sound localization acuity was quantified as the minimum audible angle (MAA) in azimuth. Pure-tone MAA was 12.3, 9.3, 8.9 and 14.5deg for frequencies of 500, 1000, 2000 and 4000 Hz, respectively. Broadband-noise MAA was 12.2deg, which indicates excellent behavioural acuity. We determined 'external cues' from head-related transfer functions of chickens. These were used to derive 'internal cues', taking into account published data on the effect of the coupled middle ears. Our estimates of the internal cues indicate that chickens likely relied on interaural time difference cues alone at low frequencies of 500 and 1000 Hz, whereas at 2000 and 4000 Hz, interaural level differences may be the dominant cue.

The roles of shape and texture in the recognition of familiar faces

The surface texture of the face is proposed to be the dominant cue in face recognition. In this study, we investigated the role of shape information in face recognition. We compared the roles of shape and surface texture in the recognition of face identity using familiar and unfamiliar hybrid faces in which the average shape from one facial identity was combined with the average texture of a different identity. In the first experiment (n = 53), participants had to match the name of a familiar person to one of eight hybrid face images. In texture trials, all images had the correct shape, but only one image had the correct texture. In shape trials, all images had the correct texture, but only one image had the correct shape. Importantly, neither task could be performed by perceptual matching. Although performance was lower for the shape trials (81%) compared to texture trials (99%), both were significantly above chance (12.5%). In the second experiment (n = 110), participants had to name hybrid faces. There were two potentially correct answers for each face image: one based on the texture and one based on the shape. Participants reported the correct name based on the texture on 61% of trials and the correct name based on the shape on 12% of trials. In the third experiment (n = 19), fMR-adaptation was used to measure the neural sensitivity to changes in the shape or texture. The core face-selective regions showed a similar sensitivity to shape and texture. These findings confirm that texture is the dominant cue for face recognition, but also show that shape plays an important role in the recognition and neural response to familiar faces.

The gatekeeper of Yersinia type III secretion is under RNA thermometer control.

Many bacterial pathogens use a type III secretion system (T3SS) as molecular syringe to inject effector proteins into the host cell. In the foodborne pathogen Yersinia pseudotuberculosis, delivery of the secreted effector protein cocktail through the T3SS depends on YopN, a molecular gatekeeper that controls access to the secretion channel from the bacterial cytoplasm. Here, we show that several checkpoints adjust yopN expression to virulence conditions. A dominant cue is the host body temperature. A temperature of 37°C is known to induce the RNA thermometer (RNAT)-dependent synthesis of LcrF, a transcription factor that activates expression of the entire T3SS regulon. Here, we uncovered a second layer of temperature control. We show that another RNAT silences translation of the yopN mRNA at low environmental temperatures. The long and short 5’-untranslated region of both cellular yopN isoforms fold into a similar secondary structure that blocks ribosome binding. The hairpin structure with an internal loop melts at 37°C and thereby permits formation of the translation initiation complex as shown by mutational analysis, in vitro structure probing and toeprinting methods. Importantly, we demonstrate the physiological relevance of the RNAT in the faithful control of type III secretion by using a point-mutated thermostable RNAT variant with a trapped SD sequence. Abrogated YopN production in this strain led to unrestricted effector protein secretion into the medium, bacterial growth arrest and delayed translocation into eukaryotic host cells. Cumulatively, our results show that substrate delivery by the Yersinia T3SS is under hierarchical surveillance of two RNATs.

Conversion of amplitude modulation to phase modulation in the human cochlea

When an amplitude modulated signal with a constant-frequency carrier is fed into a generic nonlinear amplifier, the phase of the carrier of the output signal is also modulated. This phenomenon is referred to as amplitude-modulation-to-phase-modulation (AM-to-PM) conversion and regarded as an unwanted signal distortion in the field of electro-communication engineering. Herein, we offer evidence that AM-to-PM conversion also occurs in the human cochlea and that listeners can use the PM information effectively to process the AM of sounds. We recorded otoacoustic emissions (OAEs) evoked by AM signals. The results showed that the OAE phase was modulated at the same rate as the stimulus modulation. The magnitude of the AM-induced PM of the OAE peaked generally around the stimulus level corresponding to the compression point of individual cochlear input–output functions, as estimated using a psychoacoustic method. A computational cochlear model incorporating a nonlinear active process replicates the abovementioned key features of the AM-induced PM observed in OAEs. These results indicate that AM-induced PM occurring at the cochlear partition can be estimated by measuring OAEs. Psychophysical experiments further revealed that, for individuals with higher sensitivity to PM, the PM magnitude is correlated with AM-detection performance. This result implies that the AM-induced PM information cannot be a dominant cue for AM detection, but listeners with higher sensitivity may partly rely on the AM-induced PM cue.

Sensitivity to haptic sound-localisation cues

Hearing aid and cochlear implant (CI) users often struggle to locate and segregate sounds. The dominant sound-localisation cues are time and intensity differences across the ears. A recent study showed that CI users locate sounds substantially better when these cues are provided through haptic stimulation on each wrist. However, the sensitivity of the wrists to these cues and the robustness of this sensitivity to aging is unknown. The current study showed that time difference sensitivity is much poorer across the wrists than across the ears and declines with age. In contrast, high sensitivity to across-wrist intensity differences was found that was robust to aging. This high sensitivity was observed across a range of stimulation intensities for both amplitude modulated and unmodulated sinusoids and matched across-ear intensity difference sensitivity for normal-hearing individuals. Furthermore, the usable dynamic range for haptic stimulation on the wrists was found to be around four times larger than for CIs. These findings suggest that high-precision haptic sound-localisation can be achieved, which could aid many hearing-impaired listeners. Furthermore, the finding that high-fidelity across-wrist intensity information can be transferred could be exploited in human–machine interfaces to enhance virtual reality and improve remote control of military, medical, or research robots.

Visual estimates of blood loss by medical laypeople: Effects of blood loss volume, victim gender, and perspective.

A severe hemorrhage can result in death within minutes, before professional first responders have time to arrive. Thus, intervention by bystanders, who may lack medical training, may be necessary to save a victim’s life in situations with bleeding injuries. Proper intervention requires that bystanders accurately assess the severity of the injury and respond appropriately. As many bystanders lack tools and training, they are limited in terms of the information they can use in their evaluative process. In hemorrhage situations, visible blood loss may serve as a dominant cue to action. Therefore, understanding how medically untrained bystanders (i.e., laypeople) perceive hemorrhage is important. The purpose of the current study was to investigate the ability of laypeople to visually assess blood loss and to examine factors that may impact accuracy and the classification of injury severity. A total of 125 laypeople watched 78 short videos each of individuals experiencing a hemorrhage. Victim gender, volume of blood lost, and camera perspective were systematically manipulated in the videos. The results revealed that laypeople overestimated small volumes of blood loss (from 50 to 200 ml), and underestimated larger volumes (from 400 to 1900 ml). Larger volumes of blood loss were associated with larger estimation errors. Further, blood loss was underestimated more for female victims than male victims and their hemorrhages were less likely to be classified as life-threatening. These results have implications for training and intervention design.

High temperature attenuates testicular responses in tree sparrow (Passer montanus)

The majority of birds use environmental cues to time their reproduction. Photoperiod is the most dominant cue, but other environmental factors may play a critical role in successful reproduction. Some previous studies show the effect of temperature on the timing of nest building and reproduction. Here we tested if the temperature can modulate the reproductive responses of tree sparrows. Three experiments were performed on adult male birds. In experiment 1, birds (n = 5/group) were exposed to either high (30 ± 2 °C) or low temperature (20 ± 2 °C). Change in body mass, bill color, and testes volume was recorded every 30 days. In experiment 2, a similar temperature protocol was followed, but birds were euthanized after 30 days. In experiment 3, birds were first exposed to SD (8L:16D) for 30 days but either with high (30 ± 2 °C) or low temperature (20 ± 2 °C). After 30 days, birds were exposed to LD (14L:10D), but half of the high-temperature birds were moved to low temperature, and half of the low-temperature birds were moved to high temperature. After 30 days, all birds were euthanized. In experiment 2 and 3 immediately after euthanization birds, blood samples were collected, serum was used for hormone assay. mRNA levels of thyroid-stimulating hormone-β (Tshβ), type 2 deiodinase (Dio2), type 3 deiodinase (Dio3), gonadotropin-releasing hormone (GnRH) and gonadotropin inhibitory hormone (GnIH) were measured in hypothalamic tissue. Results from experiment 1 show that high temperature attenuates the testicular responses and accelerates the timing of regression. Experiment 2 shows that on day 30, testicular responses are similar, but reproductive genes express differentially in two groups. Experiment 3 shows that exposure to high temperatures during the photosensitive stage affects the testicular response at the poststimulatory state. Together, these findings suggest that high temperature modulates reproductive responses of tree sparrow.

Do we need two ears to perceive the distance of a virtual frontal sound source?

The present study investigated whether the perception of virtual auditory distance is binaural, monaural, or both. Listeners evaluated the distance of a frontal source of pink noise simulated in a room via headphones. Experiment 1 was performed with eyes closed in a soundproof booth. Experiment 2 was performed with eyes open in the room used to create the stimuli. Individualized and non-individualized stimuli were compared. Different conditions for controlling sound level were tested. The amount of binaural information in the stimuli was varied by mixing the left and right ear signals in different proportions. Results showed that the use of non-individualized stimuli did not impair distance perception. Binaural information was not used by naive listeners to evaluate distance, both with and without visual information available. However, for some listeners, a complete absence of binaural information could disrupt distance evaluation with headphones. Sound level was a dominant cue used by listeners to judge for distance, and some listeners could also reliably use reverberation-related changes in spectral content. In the absence of specific training, artificial manipulation of sound level greatly altered distance judgments.

서울말 /ᅩ/와 /ᅮ/의 지각특성

Previous studies have confirmed that /o/ and /u/ in Seoul Korean are undergoing a merger in the F1/F2 space, especially for female speakers. As a substitute parameter for formants, it is reported that female speakers use phonation (H1-H2) differences to distinguish /o/ from /u/. This study aimed to explore whether H1-H2 values are being used as perceptual cues for /o/-/u/. A perception test was conducted with 35 college students using /o/ and /u/ spoken by 41 females, which overlap considerably in the vowel space. An acoustic analysis of 182 stimuli was also conducted to see if there is any correspondence between production and perception. The identification rate was 89% on average, 86% for /o/, and 91% for /u/. The results confirmed that when /o/ and /u/ cannot be distinguished in the F1/F2 space because they are too close, H1-H2 differences contribute significantly to the separation of the two vowels. However, in perception, this was not the case. H1-H2 values were not significantly involved in the identification process, and the formants (especially F2) were still dominant cues. The study also showed that even though H1-H2 differences are apparent in females

Cues used by dentists in the early detection of oral cancer and oral potentially malignant lesions: findings from the National Dental Practice-Based Research Network

The aim of this study was to assess the influence of clinical cues on risk assessment of cancer-associated mucosal abnormalities. We differentiated lesions with a low risk from those with a high risk for premalignancy or malignancy by using 4 cues: (1) color, (2) location, (3) induration, and (4) pain on exploration. Combinations of color and location were presented through 8 photographs, with induration and pain status variably presented in the standardized history and physical findings. This created 16 clinical scenarios (vignettes) that were permutations of the 4 cues. Three questions assessed the extent to which each cue was used in obtaining a clinical impression as to whether a lesion was benign, premalignant, or malignant. Completed vignette questionnaires were obtained from 130 of 228 invited dentists, (two-thirds males; 79% white; mean age 52 years; average weekly hours of practice 33 hours). Only 40% of the responding dentists had statistically significant decision policies to assign a clinical diagnosis of a lesion as benign, premalignant, or malignant. Lesion location and color were the 2 dominant cues. As a cue, induration was used as a cue by more of the respondents in determining a clinical diagnosis of malignancy, and pain was infrequently used as a cue. Many dentists do not to have a decision strategy for the clinical diagnosis and risk stratification of oral potentially malignant lesions.

The effect of audio cues and sound source stimuli on the perception of approaching objects

Objects that move in depth on an approaching trajectory (looming) are often encountered in both the real and virtual worlds. Examples include navigating oncoming traffic, and sporting and gaming activities where judgements are made to avoid or attack approaching objects. How people react to looming objects may impact on their survival and progression in the real, virtual, and gaming worlds, and relies on a person’s ability to precisely interpret movement and depth cues. Psychological studies investigating auditory looming often depict an object’s movement using simple audio cues (primarily amplitude increase) which are applied to tones (often sine or triangle waves) which are not normally encountered in the natural world. Whilst these studies provide valuable information about human perception and responses, technological advances allow us to present complex auditory stimuli with a range of audio cues and real-world sound sources, and to collect measurements on human perception and responses to ecologically valid stimuli.In this study we investigate human responses to audio cues for movement in depth, and how the cues affect people’s responses to the approaching object. We present an experiment on human perception where observers respond to auditory looming stimuli with real-world sounds that contain multiple audio cues, and introduce the direct-to-reverberant sound energy ratio as an audio cue. We measure the participants responses to the stimuli, asking them to indicate the approaching object’s perceived contact time (measuring their amount of over-/underestimation); to rate their emotional (valence and arousal) responses; and to rate the engagement quality of the stimuli. Our results show that listener’s responses to the audio cues differed, revealing a hierarchy across the individual audio cues, with the amplitude increase being the most dominant cue, followed by the direct-to-reverberant energy ratio. The results also demonstrated that conditions with multiple audio cues prompted earlier estimates of the contact times, greater arousal and engagement ratings, than single audio cues; and that real world sound sources prompted significantly greater engagement ratings than both the artificial sound sources.