Neural entrainment is strongest to the spectral flux of slow music and depends on familiarity and beat salience

Neural activity in the auditory system synchronizes to sound rhythms, and brain environment synchronization is thought to be fundamental to successful auditory perception. Sound rhythms are often operationalized in terms of the sound's amplitude envelope. We hypothesized that, especially for music, the envelope might not best capture the complex spectrotemporal fluctuations that give rise to beat perception and synchronize neural activity. This study investigated 1) neural entrainment to different musical features, 2) tempo dependence of neural entrainment, and 3) dependence of entrainment on familiarity, enjoyment, and ease of beat perception. In this electroencephalography study, 37 human participants listened to tempo modulated music (1 to 4 Hz). Independent of whether the analysis approach was based on temporal response functions (TRFs) or reliable components analysis (RCA), the spectral flux of music, as opposed to the amplitude envelope, evoked strongest neural entrainment. Moreover, music with slower beat rates, high familiarity, and easy to perceive beats elicited the strongest neural response. Based on the TRFs, we could decode music stimulation tempo, but also perceived beat rate, even when the two differed. Our results demonstrate the importance of accurately characterizing musical acoustics in the context of studying neural entrainment, and demonstrate the sensitivity of entrainment to musical tempo, familiarity, and beat salience.

Activation-Inhibition dynamics of the oscillatory bursts of the human EEG during resting state. The macroscopic macroscopic temporal range of few seconds

The ubiquitous brain oscillations occur in bursts of oscillatory activity. The present report tries to define the statistical characteristics of electroencephalographical (EEG) bursts of oscillatory activity during resting state in humans to define (i) the statistical properties of amplitude and duration of oscillatory bursts, (ii) its possible correlation, (iii) its frequency content, and (iv) the presence or not of a fixed threshold to trigger an oscillatory burst. The open eyes EEG recordings of five subjects with no artifacts were selected from a sample of 40 subjects. The recordings were filtered in frequency ranges of 2 Hz wide from 1 to 99 Hz. The analytic Hilbert transform was computed to obtain the amplitude envelopes of oscillatory bursts. The criteria of thresholding and a minimum of three cycles to define an oscillatory burst were imposed. Amplitude and duration parameters were extracted and they showed durations between hundreds of milliseconds and a few seconds, and peak amplitudes showed a unimodal distribution. Both parameters were positively correlated and the oscillatory burst durations were explained by a linear model with the terms peak amplitude and peak amplitude of amplitude envelope time derivative. The frequency content of the amplitude envelope was contained in the 0–2 Hz range. The results suggest the presence of amplitude modulated continuous oscillations in the human EEG during the resting conditions in a broad frequency range, with durations in the range of few seconds and modulated positively by amplitude and negatively by the time derivative of the amplitude envelope suggesting activation-inhibition dynamics. This macroscopic oscillatory network behavior is less pronounced in the low-frequency range (1–3 Hz).

An influence of characteristics of amplitude fluctuation on detectability of alert sound of electric powered vehicles

The motor sound on electric powered vehicle is quiet at low speeds. Thus, pedestrians have difficulty detecting the vehicles approaching them under urban noise. Although the vehicles were designed to play an alert sound to solve this problem, it has not been solved yet. Our previous studies found that characteristics of amplitude fluctuation, fluctuation frequency, non-periodic fluctuation and amplitude envelope, are effective to make them detect approaching vehicles. However, those studies were investigated under only a specific actual environment, weren't examined validity of detectability in those studies. Here, this paper investigates under another actual environment, examine the validity. Investigations were carried out by using synthesized complex sounds which were designed to have periodic and non-periodic amplitude fluctuations. Those complex sounds have characteristics of amplitude fluctuations in gasoline powered vehicle. Amplitude envelopes such as modulation wave in amplitude-modulated sound were set for deviations for time and amplitude, and amplitude-modulated complex sounds were synthesized using sine wave, sawtooth wave, and rectangle wave. Then, their effects on detectability by pedestrians were assessed in another actual environment. The results found that amplitude fluctuation enhances the ability with which people detect approaching electric powered vehicles in case of some complex sound.

Neural detection of changes in amplitude rise time in infancy.

Amplitude rise times play a crucial role in the perception of rhythm in speech, and reduced perceptual sensitivity to differences in rise time is related to developmental language difficulties. Amplitude rise times also play a mechanistic role in neural entrainment to the speech amplitude envelope. Using an ERP paradigm, here we examined for the first time whether infants at the ages of seven and eleven months exhibit an auditory mismatch response to changes in the rise times of simple repeating auditory stimuli. We found that infants exhibited a mismatch response to the oddball rise time that was more positive at seven than eleven months of age. At eleven months, there was a left-lateralised shift to a mismatch negativity. Infants’ ability to detect changes in rise time was generally robust, with a range of oddball stimuli with different rise times each eliciting a mismatch response from 85% of infants. A lateralised effect indicated that the size of the mismatch response varied as the change in rise time became easier to detect. The mismatch response to the different rise time oddballs also stabilised as infants got older. The results indicate that neural processing of changes in rise time develops early in life, supporting the possibility that early speech processing is facilitated by neural sensitivity to these acoustic cues to rhythm.

The Impact of Temporally Coherent Visual Cues on Speech Perception in Complex Auditory Environments

Speech perception often takes place in noisy environments, where multiple auditory signals compete with one another. The addition of visual cues such as talkers’ faces or lip movements to an auditory signal can help improve the intelligibility of speech in those suboptimal listening environments. This is referred to as audiovisual benefits. The current study aimed to delineate the signal-to-noise ratio (SNR) conditions under which visual presentations of the acoustic amplitude envelopes have their most significant impact on speech perception. Seventeen adults with normal hearing were recruited. Participants were presented with spoken sentences in babble noise either in auditory-only or auditory-visual conditions with various SNRs at −7, −5, −3, −1, and 1 dB. The visual stimulus applied in this study was a sphere that varied in size syncing with the amplitude envelope of the target speech signals. Participants were asked to transcribe the sentences they heard. Results showed that a significant improvement in accuracy in the auditory-visual condition versus the audio-only condition was obtained at the SNRs of −3 and −1 dB, but no improvement was observed in other SNRs. These results showed that dynamic temporal visual information can benefit speech perception in noise, and the optimal facilitative effects of visual amplitude envelope can be observed under an intermediate SNR range.

Rise Time Perception, Phonological Processing, and Reading in Brazilian Portuguese-Speaking Schoolchildren

<b><i>Background/Aims:</i></b> Studies of people with dyslexia have pointed to the ability to perceive the amplitude envelope rise time (“beat” perception) as a possible cause of phonological processing (PhP) difficulties in this population. However, there are very few studies about the relationships between such skills in the non-dyslexic school population. <b><i>Methods:</i></b> We investigated the influence of the beat perception ability on PhP and reading skills of 93 Brazilian Portuguese-speaking schoolchildren from the 3rd to the 5th year, with data on reading, phonological awareness (PhA), lexical access, phonological operational memory, and perception of amplitude envelope rise time. To verify the possible effects of age, gender, and school grade on the tasks in the study, we directly included these variables in the models. <b><i>Results:</i></b> Modeling structural equations showed that beat perception did not influence PhP or reading skills, but only the tasks of repetition of words and pseudowords. These tasks may be related because of the demand for phonological working memory necessary to perform the beat perception task rather than a possible connection between this and phonological abilities, as reported in the literature. <b><i>Conclusion:</i></b> We suspect beat perception could be of relevance only for subjects with altered reading and/or a deficit in PhP. Further studies will indicate whether the rise time of the amplitude envelope is an essential acoustic clue only for those individuals whose PhA ability is not fully present.

Acoustics of the banjo: theoretical and numerical modelling

A previous paper [Woodhouse et al., Acta Acustica 5, 15 (2021) https://doi.org/10.1051/aacus/2021009] showed acoustical measurements of an American 5-string banjo alongside similar measurements on a guitar, revealing a strong contrast in bridge admittance. Theoretical and numerical modelling is now presented to probe the physics behind this contrast. Without the bridge and strings, the banjo membrane has a rising trend of admittance associated with its modal density, and it has a distinctive pattern of sound radiation because an ideal membrane has no critical frequency. When the bridge and strings are added to the banjo, three formants shape the amplitude envelope of the admittance. One is associated with local effects of mass and stiffness near the bridge, and is sensitive to bridge mass and the break angle of the strings over the bridge. The other two formants are associated with dynamical behaviour of the bridge, analogous to the “bridge hill” in the violin.