Hazardous sound outputs of white noise devices intended for infants

Effects of white noise on preterm infants in the neonatal intensive care unit: A meta-analysis of randomised controlled trials

AIM

To critically assess the effects of white noise on the pain level, weight gain and vital signs (heart rate, respiratory rate and oxygen saturation) of preterm infants in neonatal intensive care units (NICUs).

DESIGN

A systematic review and meta-analysis of randomised controlled trials (RCTs).

METHODS

Ten databases (PubMed, Cochrane Library, Embase, Web of Science, CINAHL, PsycINFO, SinoMed, China National Knowledge Infrastructure, VIP and Wanfang Data) were systematically reviewed from inception to July 2022. Two reviewers evaluated the risk of bias separately using the Cochrane Collaboration criteria and extracted data using a predesigned information form.

RESULTS

The meta-analysis included eight eligible RCTs. According to statistical analysis, white noise significantly affected the pain level, weight gain, heart rate, respiratory rate and oxygen saturation in preterm infants. Regardless of the outcome measurement timing, gestational age and birth weight of preterm infants, subgroup analysis demonstrated that white noise reduced the pain level, heart rate and respiratory rate and promoted weight gain in preterm infants in NICUs.

CONCLUSION

White noise is a practical and potentially useful therapy for premature neonates in NICUs. No Patient or Public Contribution.

Induction Mechanism of Auditory-Assisted Vision for Target Search Localization in Mixed Reality (MR) Environments

In MR (mixed reality) environments, visual searches are often used for search and localization missions. There are some problems with search and localization technologies, such as a limited field of view and information overload. They are unable to satisfy the need for the rapid and precise location of specific flying objects in a group of air and space targets under modern air and space situational requirements. They lead to inefficient interactions throughout the mission process. A human being’s decision and judgment will be affected by inefficient interactions. Based on this problem, we carried out a multimodal optimization study on the use of an auditory-assisted visual search for localization in an MR environment. In the spatial–spherical coordinate system, the target flight object position is uniquely determined by the height h, distance r, and azimuth θ. Therefore, there is an urgent need to study the cross-modal connections between the auditory elements and these three coordinates based on a visual search. In this paper, an experiment was designed to study the correlation between auditory intuitive perception and vision and the cognitive induction mechanism. The experiment included the three cross-modal mappings of pitch–height, volume–distance, and vocal tract alternation–spatial direction. The research conclusions are as follows: (1) Visual cognition is induced by high, medium, and low pitches to be biased towards the high, medium, and low spatial regions of the visual space. (2) Visual cognition is induced by loud, medium, and low volumes to be biased towards the near, middle, and far spatial regions of the visual space. (3) Based on the HRTF application, the vocal track alternation scheme is expected to significantly improve the efficiency of visual interactions. Visual cognition is induced by left short sounds, right short sounds, left short and long sounds, and right short and long sounds to be biased towards the left, right, left-rear, and right-rear directions of visual space. (4) The cognitive load of search and localization technologies is significantly reduced by incorporating auditory factors. In addition, the efficiency and effect of the accurate search and positioning of space-flying objects have been greatly improved. The above findings can be applied to the research on various types of target search and localization technologies in an MR environment and can provide a theoretical basis for the subsequent study of spatial information perception and cognitive induction mechanisms in an MR environment with visual–auditory coupling.

Acoustic Stimuli Can Improve and Impair Somatosensory Perception

The integration of stimuli from different sensory modalities forms the basis for human perception. While the relevant impact of visual stimuli on the perception of other sensory modalities is recognized, much less is known about the impact of auditory stimuli on general sensory processing. This study aims to investigate the effect of acoustic stimuli on the processing of somatosensory stimuli using real noise (i.e., unpleasant everyday noise, RN) and neutral white noise (WN). To this purpose, we studied 20 healthy human subjects between 20 and 29 years of age (mean: 24, SD: ±1.9 years sex ratio 1:1). Somatosensory perception was evaluated using mechanical detection threshold (MDT) of the skin on the back of the dominant hand. To investigate the underlying mechanisms in the brain, fMRI was performed while applying acoustic stimulation (RN and WN) and tactile stimulation of the dominant hand. Here we show that acoustic stimulation with noise alters the perception of touch on the skin. We found that the effect of RN and WN differed. RN leads to an improved tactile perception, whereas WN impaired tactile perception. These changes go along with significant differences in brain activity and connectivity. WN is associated with a significant increase in brain activity in multiple brain areas such as the auditory and somatosensory cortex, parietal association cortex, and the thalamus compared to RN. With tactile stimulation of the skin, the flow of information in these brain areas is altered. While with RN the information flow from the thalamus to the somatosensory cortex is prominent, the network activity pattern changes under WN revealing an increase in interaction between multiple networks. Unpleasant noise inhibits the multisensory integration and enables a more efficient unimodal perception in the somatosensory system, improving perception. Whether this is to be interpreted as a temporary increase in phasic alertness or by a stronger filter function of the thalamus with a preference for unimodal stimuli is still open for debate.