High-Resolution Audio with Inaudible High-Frequency Components Induces a Relaxed Attentional State without Conscious Awareness

Audiovisual messages may improve the processing of traffic information and driver attention during partially automated driving: An EEG study

Partially autonomous vehicles can help minimize human errors. However, being free from some driving subtasks can result in a low vigilance state, which can affect the driver's attention towards the road. The present study first tested whether drivers of partially autonomous vehicles would benefit from the addition of auditory versions of the messages presented in variable message signs (VMS), particularly, when they find themselves in a monotonous driving situation. A second aim was to test whether the addition of auditory messages would also produce an indirect effect on the driver's vigilance, improving performance on other driving subtasks not related to the message processing. Forty-three volunteers participated in a driving simulator study. They completed two tasks: (a) a VMS task, where they had to regain manual control of the car if the VMS message was critical, and (b) a car-following task, where they had to pay attention to the preceding car to respond to occasional brake events. Behavioral and EEG data were registered. Overall, results indicated that the addition of audio messages helped drivers process VMS information more effectively and maintain a higher level of vigilance throughout the driving time. These findings would provide useful information for the development of partially automated vehicles, as their design must guarantee that the driver remains attentive enough to assume control when necessary.

Effects of broadband music and audible band music on relaxation states and cognitive function in young adults: a randomized controlled trial

BACKGROUND

Although broadband music with inaudible high-frequency components may benefit human well-being, this research area is largely unexplored and lacks sufficient studies on the topic. This study aimed to investigate and compare the effects of broadband and audible band music on relaxation states and cognitive function in young adults.

METHODS

A single-blind randomized controlled trial was conducted in a professional soundproof laboratory from December 22, 2022, to January 18, 2023 with 32 participants randomly assigned to two groups, "Day 1 broadband + Day 2 audible band" (n = 16) and "Day 1 audible band + Day 2 broadband" (n = 16), listening to either broadband or audible band music (the same music piece played on the piano and harp) for two sessions of 15 min each on two consecutive days. Cognitive function was measured using CNS Vital Signs at pre-listening, after the 1st session, and after the 2nd session, while heart rate was monitored throughout the experiment. Visual Analog Scale was also administered for self-reported arousal, stress, thinking ability, and attention following each listening session.

RESULTS

No significant differences were found in heart rate, cognitive flexibility, and executive function between the broadband listening group and the audible band-listening group (p > 0.05). However, the broadband group exhibited significant differences in mean heart rate at several time points, as well as a significant improvement in VAS stress level during the 2nd listening session compared to the 1st (p < 0.05). On the other hand, significant improvements in cognitive flexibility and executive function were observed in the audible band group across different time points (p < 0.05).

CONCLUSION

Comparative analysis showed that broadband and audible band music influenced cognitive function differently. Short-term audible band music listening significantly improved cognitive flexibility and executive function, while short-term broadband music listening significantly reduced reaction time in cognitive tests. Additionally, broadband music consistently resulted in lower mean heart rates compared to audible band music at all time points, suggesting that it may be more effective in promoting relaxation and reducing stress, although these differences were not statistically significant. Since the cognitive enhancing effects of broadband music may be counteracted by the drowsy effect of the selected relaxing music, using different types of music may be necessary to confirm its effects in future studies.

Subjective effects of broadband water sounds with inaudible high-frequency components

This study aimed to investigate the effects of reproducing an ultrasonic sound above 20 kHz on the subjective impressions of water sounds using psychological and physiological information obtained by the semantic differential method and electroencephalography (EEG), respectively. The results indicated that the ultrasonic component affected the subjective impression of the water sounds. In addition, regarding the relationship between psychological and physiological aspects, a moderate correlation was confirmed between the EEG change rate and subjective impressions. However, no differences in characteristics were found between with and without the ultrasound component, suggesting that ultrasound does not directly affect the relationship between subjective impressions and EEG energy at the current stage. Furthermore, the correlations calculated for the left and right channels in the occipital region differed significantly, which suggests functional asymmetry for sound perception between the right and left hemispheres.

Auditory brainstem responses to high-resolution audio sounds: Effects of anti-alias filters

Despite the superior technical specifications of high-resolution audio in comparison to conventional compact discs (CDs) and digital versatile discs (DVDs), whether and how high-resolution audio leads to an improved subjective listening experience remains unclear. The sound quality of conventional digital formats is deteriorated by temporal blur, which is caused by a high-cut filter applied to avoid aliasing of a digital sound source, resulting in spurious artificial sound energy before and after the actual sound onset. Using sound materials of high-resolution audio grade, this study investigated the effects of filter-induced temporal blur on the auditory neural pathway from the cochlea through the rostral brainstem by measuring the auditory brainstem responses (ABRs) of participants with normal hearing. The participants (N = 24) listened to 0.1-ms clicks, with and without a high-cut filter of 22 kHz or 11 kHz applied to them. The amplitudes and latencies of five ABR waves (<10 ms) revealed no significant effects caused by filtering. The participants could not distinguish between the original and the 22-kHz filtered click sounds, while they could distinguish between the original and the 11-kHz filtered sounds. These results indicate that a CD-level anti-alias filter does not affect initial auditory processing and the sound difference is not discernible, at least for artificial sounds with a simple acoustic structure.

High-frequency sound components of high-resolution audio are not detected in auditory sensory memory

High-resolution digital audio is believed to produce a better listening experience than the standard quality audio, such as compact disks (CDs) and digital versatile disks (DVDs). One common belief is that high-resolution digital audio is superior due to the higher frequency (> 22 kHz) of its sound components, a characteristic unique to this audio. This study examined whether sounds with high-frequency components were processed differently from similar sounds without these components in the auditory cortex. Mismatch negativity (MMN), an electrocortical index of auditory deviance detection in sensory memory, was recorded in young adults with normal hearing (N = 38) using two types of white noise bursts: original sound and digitally filtered sound from which high-frequency components were removed. The two sounds did not produce any MMN response and could not be discriminated behaviourally. In conclusion, even if high-resolution audio is superior to the standard format, the difference is apparently not detectable at the cortical level.

Augmentation of Positive Valence System-Focused Cognitive Behavioral Therapy by Inaudible High-Frequency Sounds for Anhedonia: A Trial Protocol for a Pilot Study

IMPORTANCE

Recent conceptualizations in Research Domain Criteria have indicated that anhedonia, 1 of 2 core symptoms of depression, which can be treatment resistant, is associated with deficits in the positive valence system, and inaudible high-frequency sound therapy has been shown to enhance reward-related brain circuitry. Hence, cognitive behavioral therapy focusing on the positive valence system enhanced with sound therapy could have a synergistic effect on anhedonia.

OBJECTIVE

To test the augmentation effect of inaudible high-frequency sounds on the efficacy of positive valence system-focused cognitive behavioral therapy to treat anhedonia.

DESIGN, SETTING, AND PARTICIPANTS

In this individual-level allocation, exploratory, single-center randomized superiority pilot trial, patients, therapists, and evaluators will be masked to intervention or placebo assignment. The trial will take place at a national psychiatric referral hospital in Tokyo, Japan, among 44 adult patients with clinically significant anhedonia and moderate to severe depression. Outcomes will be analyzed following the intent-to-treat principle using a repeated-measures mixed model.

INTERVENTION

The intervention group will participate in 8 weekly sessions of positive valence system-focused cognitive behavioral therapy with in-session exposure to an inaudible high-frequency sound; the comparison group will undergo cognitive behavioral therapy with in-session exposure to a placebo sound.

MAIN OUTCOMES AND MEASURES

The primary outcome is anhedonia assessed using the self-reported Snaith-Hamilton Pleasure Scale. The secondary outcome is anhedonia assessed using the clinician-administered version of the Snaith-Hamilton Pleasure Scale.

DISCUSSION

Recruitment for this study began in May 2018, and the projected date of final allocation is January 2020. A total of 21 eligible patients were registered for participation as of May 30, 2019. To date, treatments for depression do not guarantee clinically successful outcomes. This pilot trial will provide preliminary evidence of the augmentation effect of high-frequency inaudible sounds on cognitive behavioral therapy for anhedonia. Overall, exposure to an inaudible high-frequency sounds does not require attentional or cognitive effort from either patients or therapists; therefore, results from a future confirmative trial could indicate that cognitive behavioral therapy can be augmented in an effortless manner.

TRIAL REGISTRATION

umin.ac.jp/ctr Identifier: UMIN000031948.

Inaudible components of the human infant cry influence haemodynamic responses in the breast region of mothers

Distress vocalizations are fundamental for survival, and both sonic and ultrasonic components of such vocalizations are preserved phylogenetically among many mammals. On this basis, we hypothesized that ultrasonic inaudible components of the acoustic signal might play a heretofore hidden role in humans as well. By investigating the human distress vocalization (infant cry), here we show that, similar to other species, the human infant cry contains ultrasonic components that modulate haemodynamic responses in mothers, without the mother being consciously aware of those modulations. In two studies, we measured the haemodynamic activity in the breasts of mothers while they were exposed to the ultrasonic components of infant cries. Although mothers were not aware of ultrasounds, the presence of the ultrasounds in combination with the audible components increased oxygenated haemoglobin concentration in the mothers' breast region. This modulation was observed only when the body surface was exposed to the ultrasonic components. These findings provide the first evidence indicating that the ultrasonic components of the acoustic signal play a role in human mother-infant interaction.

Music and Noise: Same or Different? What Our Body Tells Us

In this article, we consider music and noise in terms of vibrational and transferable energy as well as from the evolutionary significance of the hearing system of Homo sapiens. Music and sound impinge upon our body and our mind and we can react to both either positively or negatively. Much depends, in this regard, on the frequency spectrum and the level of the sound stimuli, which may sometimes make it possible to set music apart from noise. There are, however, two levels of description: the physical-acoustic description of the sound and the subjective-psychological reactions by the listeners. Starting from a vibrational approach to sound and music, we first investigate how sound may activate the sense of touch and the vestibular system of the inner ear besides the sense of hearing. We then touch upon distinct issues such as the relation between low-frequency sounds and annoyance, the harmful effect of loud sound and noise, the direct effects of overstimulation with sound, the indirect effects of unwanted sounds as related to auditory neurology, and the widespread phenomenon of liking loud sound and music, both from the point of view of behavioral and psychological aspects.