Sound Duration Research Articles

Sound emission ofMacrobrachium rosenbergiiduring feeding activity

Passive acoustics monitoring (PAM) has been used to detect crustacean feeding activity. The aim of the present study was to evaluate the sound emission of the giant freshwater prawn Macrobrachium rosenbergii during feeding a commercial pelleted food in captivity, as well as described the sound generation mechanism and main acoustic variables for the first time. The structure responsible for sound emission was identified based on simultaneous audio and video recordings. Fourteen animals divided into three size classes were recorded individually. The acoustic parameters (sound duration, minimum, maximum and peak frequency and sound pressure level) of 80 sound pulses were analysed for each size classes. The giant freshwater prawn emits click sound when closing the mandibles to shred the food, as they collide with each other. Minimum and peak frequency were similar among the size classes, while the other acoustic parameters were significantly different, but they did not follow an apparent pattern in relation to the size of the prawns. The M. rosenbergii emits sound during feed consumption, and the acoustic parameters obtained in the present study could be useful to monitor feeding activity in prawn farming.

Survey of Acoustic Output in Neonatal Brain Protocols.

Auditory and non-auditory safety concerns associated with the appreciable sound levels inherent to magnetic resonance imaging (MRI) procedures exist for neonates. However, current gaps in knowledge preclude making an adequate risk assessment. To measure acoustic exposure (duration, intensity, and frequency) during neonatal brain MRI and compare these values to existing hearing safety limits and data. Phantom. Cylindrical doped water phantom. Neonatal brain protocols acquired at 1-3 T. Scans in the model protocol included a diffusion tensor imaging scan, a gradient echo, a three-dimensional (3D) fast spin echo, 3D fast spin-echo single-shots, a spin echo, a turbo spin echo, a 3D arterial spin labeling scan, and a susceptibility-weighted fast spin-echo scan. The sound pressure levels (SPLs), frequency profile, and durations of five neonatal brain protocols on five MR scanners (scanner A [3 T, whole-body], scanner B [1.5 T, whole-body], scanner C [1 T, dedicated neonatal], scanner D [1.5 T, whole-body], and scanner E [3 T, whole-body]) located at three different sites were recorded. The SPLs were then compared to the International Electrotechnical Commission (IEC) hearing safety limit and existing data of infant non-auditory responses to loud sounds to assess risk. Mann-Whitney U test to assess whether the dedicated neonatal scanner was quieter than the other machines. The average level A-weighted equivalent value (LAEQ) across all five MR scanners and scans was 92.88 dBA and the range of LAEQs across all five MR scanners and scans was 80.8-105.31 dBA. The duration of the recorded neonatal protocols maintained by neonatal scanning facilities (from scanners A, B, and C) ranged from 27:33 to 37:06 minutes. Neonatal protocol sound levels straddled existing notions of risk, exceeding sound levels known to cause non-auditory responses in neonates but not exceeding the IEC MRI SPL safety limit. 5 TECHNICAL EFFICACY: Stage 5.

Minimal time to determine moving sound source direction in patients with sensorineural hearing loss

Minimal time to determine the direction of azimuthal motion was measured in normally hearing subjects and in patients with sensorineural hearing loss (SNHL). A moving sound image was formed by counter-directional change of the amplitude on two loudspeakers placed at 1.1 m in front of the listener by azimuthal angles of ±30° in a sound-treated room. The sound image moved from the central position to the left or to the right, or in the opposite direction along 24.2° arc. An adaptive psychoacoustic procedure was used in a diapason of sound images durations from 0.1 to 1.5 s with 0.1s step. All subjects with normal hearing (N = 11) had the minimal time of 0.1 s or lower. Patients demonstrated significantly higher minimal time: 0.4, 0.5 and 0.9 s in case of mild (N = 16), moderate (N = 16) and moderately severe (N = 12) SNHL, respectively (p < 0.001, p < 0.000 1, and p < 0.000 01, Mann-Whitney U Test). Patients were divided into groups in accordance with the WHO classification. Minimal times in patients with mild and moderate SNHL did not differ (p = 0.18, Mann-Whitney U Test), but both were lower than in patients with moderately severe SNHL (p < 0.01, Mann-Whitney U Test). [This work was supported by means of the State assignment (АААА-А18-118013090245-6).]

Phasic Off responses of auditory cortex underlie perception of sound duration.

It has been proposed that sound information is separately streamed into onset and offset pathways for parallel processing. However, how offset responses contribute to auditory perception remains unclear. Here, loose-patch and whole-cell recordings in awake mouse primary auditory cortex (A1) reveal that a subset of pyramidal neurons exhibit a transient "Off" response, with its onset tightly time-locked to the sound termination and its frequency tuning similar to that of the transient "On" response. Both responses are characterized by excitation briefly followed by inhibition, with the latter mediated by parvalbumin (PV) inhibitory neurons. Optogenetically manipulating sound-evoked A1 responses at different temporal phases or artificially creating phantom sounds in A1 further reveals that the A1 phasic On and Off responses are critical for perceptual discrimination of sound duration. Our results suggest that perception of sound duration is dependent on precisely encoding its onset and offset timings by phasic On and Off responses.

Extracting Urban Sound Information for Residential Areas in Smart Cities Using an End-to-End IoT System

With rapid urbanization comes the increase of community, construction, and transportation noise in residential areas. The conventional approach of solely relying on sound pressure-level information to decide on the noise environment and to plan out noise control and mitigation strategies is inadequate. This article presents an end-to-end Internet-of-Things (IoT) system that extracts real-time urban sound metadata using edge devices, providing information on the sound type, location and duration, rate of occurrence, loudness, and azimuth of a dominant noise in nine residential areas. The collected metadata on environmental sound is transmitted to and aggregated in a cloud-based platform to produce detailed descriptive analytics and visualization. Our approach in integrating different building blocks, namely, hardware, software, cloud technologies, and signal processing algorithms to form our real-time IoT system is outlined. We demonstrate how some of the sound metadata extracted by our system are used to provide insights into the noise in residential areas. A scalable workflow to collect and prepare audio recordings from nine residential areas to construct our urban sound data set for training and evaluating a location-agnostic model is discussed. Some practical challenges of managing and maintaining a sensor network deployed at numerous locations are also addressed.

Effects of tDCS on Sound Duration in Patients with Apraxia of Speech in Primary Progressive Aphasia.

Transcranial direct current stimulation (tDCS) over the left inferior frontal gyrus (IFG) was found to improve oral and written naming in post-stroke and primary progressive aphasia (PPA), speech fluency in stuttering, a developmental speech-motor disorder, and apraxia of speech (AOS) symptoms in post-stroke aphasia. This paper addressed the question of whether tDCS over the left IFG coupled with speech therapy may improve sound duration in patients with apraxia of speech (AOS) symptoms in non-fluent PPA (nfvPPA/AOS) more than sham. Eight patients with non-fluent PPA/AOS received either active or sham tDCS, along with speech therapy for 15 sessions. Speech therapy involved repeating words of increasing syllable-length. Evaluations took place before, immediately after, and two months post-intervention. Words were segmented into vowels and consonants and the duration of each vowel and consonant was measured. Segmental duration was significantly shorter after tDCS compared to sham and tDCS gains generalized to untrained words. The effects of tDCS sustained over two months post-treatment in trained and untrained sounds. Taken together, these results demonstrate that tDCS over the left IFG may facilitate speech production by reducing segmental duration. The results provide preliminary evidence that tDCS may maximize efficacy of speech therapy in patients with nfvPPA/AOS.

Acoustic salience in emotional voice perception and its relationship with hallucination proneness.

Auditory verbal hallucinations (AVH) are reported in approximately 70% of psychotic patients, but they also may occur in approximately 10% of the healthy general population. AVH have been related to altered processing of vocal emotions at both sensory and higher-order processing stages in psychotic patients. However, it remains to be clarified whether individuals with high hallucination proneness (HP) exhibit a similar pattern of alterations. We investigated the impact of HP on vocal emotional perception and specified whether manipulations of acoustic cues, such as sound intensity and duration, related to salience changes, affect the time course of voice processing reflected in event-related potentials (ERP) of the electroencephalogram. Participants varying in HP performed a task involving the categorization of emotional nonverbal vocalizations (neutral, anger, and amusement) differing in duration and intensity. ERP results demonstrated interactive effects of HP, valence, and acoustic cues on both early (N1, P2) and late (Late Positive Potential [LPP]) processing stages. Higher HP was associated with decreased N1 and increased P2 amplitudes in response to louder and longer neutral (vs. positive) vocalizations, as well as with a larger LPP to louder and longer negative (vs. neutral) vocalizations. These findings suggest that HP is associated with changes in the processing of vocal emotions that might be related to altered salience of acoustic representations of emotions. Consistent with prior studies with psychotic patients, these findings show that altered perception of vocal emotions may additionally contribute to the experience of hallucinations in nonclinical samples.

Temporal-Framing Adaptive Network for Heart Sound Segmentation Without Prior Knowledge of State Duration.

This paper presents a novel heart sound segmentation algorithm based on Temporal-Framing Adaptive Network (TFAN), including state transition loss and dynamic inference. In contrast to previous state-of-the-art approaches, TFAN does not require any prior knowledge of the state duration of heart sounds and is therefore likely to generalize to non sinus rhythm. TFAN was trained on 50 recordings randomly chosen from Training set A of the 2016 PhysioNet/Computer in Cardiology Challenge and tested on the other 12 independent databases (2,099 recordings and 52,180 beats). And further testing of performance was conducted on databases with three levels of increasing difficulty (LEVEL-I, -II and -III). TFAN achieved a superior F1 score for all 12 databases except for 'Test-B,' with an average of 96.72%, compared to 94.56% for logistic regression hidden semi-Markov model (LR-HSMM) and 94.18% for bidirectional gated recurrent neural network (BiGRNN). Moreover, TFAN achieved an overall F1 score of 99.21%, 94.17%, 91.31% on LEVEL-I, -II and -III databases respectively, compared to 98.37%, 87.56%, 78.46% for LR-HSMM and 99.01%, 92.63%, 88.45% for BiGRNN. TFAN therefore provides a substantial improvement on heart sound segmentation while using less parameters compared to BiGRNN. The proposed method is highly flexible and likely to apply to other non-stationary time series. Further work is required to understand to what extent this approach will provide improved diagnostic performance, although it is logical to assume superior segmentation will lead to improved diagnostics.

Automated Heart Sound Signal Segmentation and Identification using Abrupt Changes and Peak Finding Detection

Abstract Conventionally, majority physicians used manual-based approach to determine heart sound parameters by manually printing heart sound signal waveform on the paper and trace heart sound parameters duration. Towards modern medical diagnostic technologies, this paper presents a modified framework of automated heart sound signal segmentation and parameters identification for deployment in computer aided auscultation. Envelope-based approach with reference information by abrupt changes and peak detection algorithm are proposed for PASCAL Classifying Heart Sounds Challenge database. Noted that the performance of segmentation process was measured by calculating the accuracy and F1-score while the heart sound parameters were identified by computing its mean and standard deviation. The findings yield F1-score and accuracy of proposed approach for segmentation and identification of normal heart sound signal at 95.29% and 91.0%, respectively. Heart sound parameters such as first sound, S1 duration, second sound, S2 duration, systole duration, diastole duration, heart cycle duration and ratio of systole and diastole were also determined. This proposed approach is suitable to be applied on two prominent heart sound signal peaks of S1 and S2, which continuously varies among samples due to the different auscultatory sites.

담화표지 ‘아’, ‘어’, ‘음’의 성별과 연령별 사용 양상

This paper quantitatively calculated the speech frequency of the discourse markers ‘a’, ‘eo’, and ‘eum’ and the speech duration of these discourse markers using the Seoul Corpus, a spontaneous speech corpus. The sound durations were confirmed with Praat, the Seoul Corpus was analyzed with Emeditor, and the results were presented by statistical analysis with R. Based on the corpus analysis, the study investigated whether a particular factor is preferred by speakers of particular categories. The most prominent feature of the corpus is that the sound durations of female speakers were longer than those of men when using the

Use of automated speech analysis and facial emotion measurements on videos to assess the effects of relaxation devices: a pilot study

Rapid relaxation installations in order to reduce stress appear more and more in public or work places. However, the effects of such devices on physiological and psychological parameters have not been scientifically tested yet. This pilot study (N=40) evaluates the variations of vocal speech and facial emotions parameters in 3-minute videos of participant recorded just before and after relaxation, on four different groups, three of them using a different rapid (15 minutes) sensorial immersion relaxation devices and a control group using no device. Vocal speech parameters included sound duration, pause mean duration, sound duration ratio, mean vocal frequency (F0), standard deviation of F0, minimum and maximum of F0, jitter and shimmer. Facial emotion analysis included neutral, happy, sad, surprised, angry, disgusted, scared, contempt, valence and arousal. The objective of this study is to evaluate different parameters of the automated vocal and facial emotions analysis that could be of use to evaluate the relaxation effect of different devices and to measure their variations in the different experimental groups. We identified significant parameters that can be of use for evaluating rapid relaxation devices, particularly voice prosody and minimum vocal frequency, and some facial emotion such as happy, sad, the valence and arousal. Those parameters allowed us to discriminate distinct effects of the different devices used: in G1 (control) and G2 (spatialized sounds), we observed a slowdown in voice prosody; in G3 (Be-Breathe) a decrease in minimum vocal frequency and an increase of arousal; while in G4 (3D-video) we found an increase in facial emotion valence (happy increasing and sad decreasing). Other parameters tested were not affected by relaxation.

Onomatopoeia in Omani Arabic

Onomatopoeia is believed to be of a widespread occurrence in all languages of the world though with different extents. Arabic language is attested to be rich in the use of onomatopoeia in speech, prose, and poetry. Omani Arabic, a unique variety of vernacular Arabic spoken in the Sultanate of Oman in the eastsouthern part of Arabia, likewise has numerous usages of onomatopoeic words in everyday life interactions. Both lexical and non-lexical onomatopoeia exist in Omani Arabic falling into three main categories: human sounds, animal sounds, and sounds associated with nature and objects. Onomatopoeic sounds appear in different syllabic forms including full syllables and non-syllabic forms with one or more consonants. The use of voiceless sounds and fricatives is more prevalent compared to other types of sounds. Cases are attested of sounds captured in diverse manners exhibiting alternation among sounds close in place of articulation as well as between emphatic sounds and their non-emphatic counterparts. The use of fricatives is used to mark the duration of sounds as opposed to the use of plosives employed to show abruptness and short duration of sounds. Morphologically, most of these words are used as verbs and derivative nouns. Reduplication is likewise used to mark the intensity and duration of actions signified by these sounds.

Relaxing and stimulating effects of odors on time perception and their modulation by expectancy.

Although several studies have reported relaxing and stimulating effects of odors on physiology and behavior, little is known about their underlying mechanisms. It has been proposed that participant expectancy could explain these activation effects. Since emotional stimuli are known to modulate time perception, here we used the temporal bisection task to determine whether odors have objective relaxing and stimulating effects by respectively slowing down or speeding up the internal clock and whether prior expectancy could alter these effects. In Experiment 1, 118 participants were presented either with a strawberry odor or an odorless blank. In Experiment 2, 132 participants were presented either with a lemon odor or an odorless blank. In both experiments, expectancy was manipulated using suggestion (verbal instructions). The stimulus was either described as relaxing or stimulating, or was not described. In the absence of prior suggestion, findings showed that, compared to participants presented with an odorless blank, participants presented with the strawberry odor underestimated sound durations (i.e., a relaxing effect) whereas participants presented with the lemon odor overestimated them (i.e., a stimulating effect). These results confirm that pleasant odors can have objective relaxing and stimulating effects by themselves, which are better explained by arousal-based mechanisms rather than attentional distraction. Furthermore, in both experiments, incongruent suggestions undid the effects of both odors without reversing them completely (i.e., strawberry did not become stimulating even if participants were told so). Both these bottom-up and top-down influences should be considered when investigating the emotional impact of odors on human behavior.

Duration modelling and evaluation for Arabic statistical parametric speech synthesis

Sound duration is responsible for rhythm and speech rate. Furthermore, in some languages phoneme length is an important phonetic and prosodic factor. For example, in Arabic, gemination and vowel quantity are two important characteristics of the language. Therefore, accurate duration modelling is crucial for Arabic TTS systems. This paper is interested in improving the modelling of phone duration for Arabic statistical parametric speech synthesis using DNN-based models. In fact, since a few years, DNN have been frequently used for parametric speech synthesis, instead of HMM. Therefore, several variants of DNN-based duration models for Arabic are investigated. The novelty consists in training a specific DNN model for each class of sounds, i.e. short vowels, long vowels, simple consonants and geminated consonants. The main idea behind this choice is the improvement that we already achieved in the quality of Arabic parametric speech synthesis by the introduction of two specific features of Arabic, i.e. gemination and vowel quantity into the standard HTS feature set. Both objective and subjective evaluations show that using a specific model for each class of sounds leads to a more accurate modelling of the phone duration in Arabic parametric speech synthesis, outperforming the state-of-the-art duration modelling systems.

Analisis Akustik Bunyi Sibilant Bahasa Jepang pada Pembelajar Bahasa Jepang di Indonesia yang Berbahasa Ibu Bahasa Jawa

Abstract
 This study aims to analyze the characteristics of Japanese sibilant sound observed from the acoustic analysis. The data of this study were in the form of sound samples from 16 respondents who spoke Javanese in Japanese language learners at the university and 8 Japanese native speakers. The respondents were asked to pronounce vocabulary containing Japanese sibilant sounds at the beginning and middle of a total of 72 words which have meaning. Then, the sample of Indonesian and Japanese respondent's sound was measured using Praat software to find their duration, intensity and Center of Gravity (CoG) of the sibilant sound. The measurement results are carried out an analysis of 2 factors, namely consonant type and sound position, using anova statistics. The duration, intensity and Center of Gravity measurement results show that the two factors (consonant type and sound position) are statistically significant. The distribution of sibilant sound duration is from 68 ms to 144 ms, and the distribution of sibilant sound intensity is from 50 dB to 60 dB. The results of the Center of Gravity (CoG) measurements show that among the learners, the CoG values ​​are in the average range of /s/ = 7 kHz, /z/ = 6 kHz, /ɕ/ = 5 kHz, and /ʑ/ = 4 kHz, while among the native speakers, the CoG values ​​are in the average range of /s/ = 8 kHz, /z/ = 8 kHz, /ɕ/ = 6 kHz, and /ʑ/ = 6 kHz.
 Key words: (a) acoustic analysis, (b) Japanese sibilant, (c) duration, (d) Center of Gravity (CoG)

FIBONACCI DİZİSİ VE ALTIN ORAN’IN MÜZIKTEKİ UYGULAMALARININ İNCELENMESİ

In studies presented in the literature, relationships between music and mathematics can sometimes be observed. Leonardo Fibonacci (1170-1250) is well known with the Fibonacci Sequence used to identify numbers in various music elements. In related studies, these numbers have been used to demonstrate the existence of the ‘Golden Ratio’ using methods and theories borrowed from the components of music. Nevertheless, this relationship has subsequently been seen inaccurate. The selected works from Chopin, Mozart, Beethoven and Bartók have previously been used to study the Fibonacci Sequence and Golden Ratio, and these works are discussed in this paper in the context of musical and mathematical theories. For musical works that allegedly used the Fibonacci Sequence and the Golden Ratio, we examined the measure or rhythms (sound duration)within these works; we found these studies yielded values close to the terms of the Fibonacci Sequence, and the determined values of the Golden Ratio were 0.618, 1.618, and 0.382. It was determined that the accuracy of the Fibonacci Sequence and the Golden Ratio expressed in selected works of European art music are controversial within the framework of relevant studies.

Comparative Analysis of Spontaneous Swallowing Sounds Between the Young and the Elderly: An Indicator of Aging Dysphagia

The study aims at comparatively analyzing the characteristics of the swallowing sound of the young and the elderly. A total of 100 eligible human subjects were divided into two groups: A young group (n = 50, age 19–30 years, sex ratio 1:1) and an elderly group (n = 50, 60–85 years, sex ratio 1:1). The neck circumference (at the thyroid cartilage level) and the body mass index (BMI) of the subjects were measured. The spontaneous swallowing sound within 20 min was recorded and analyzed using Raven Pro 1.5.0. The parameters included were swallows per minute (SPM), swallowing sound duration (SSD), energy delivered by one swallowing sound (E), time of consuming half E(E0.5t), and percentage of time spent on half-energy consumption for a single swallowing sound (E0.5Δt). Statistical analysis performed using R-3.4.0. NC showed no difference between the two groups (34.31 ± 3.45 cm versus 33.95 ± 3.00 cm, P= 0.5789). Compared to the young group, the elderly group showed a higher BMI, lesser SPM, longer SSD, more Es in each swallow, longer E0.5t, and identical E0.5Δt . The elderly showed reduced SPM and prolonged SSD.

The impact of temporal fine structure and signal envelope on auditory motion perception.

The majority of psychoacoustic research investigating sound localization has utilized stationary sources, yet most naturally occurring sounds are in motion, either because the sound source itself moves, or the listener does. In normal hearing (NH) listeners, previous research showed the extent to which sound duration and velocity impact the ability of listeners to detect sound movement. By contrast, little is known about how listeners with hearing impairments perceive moving sounds; the only study to date comparing the performance of NH and bilateral cochlear implant (BiCI) listeners has demonstrated significantly poorer performance on motion detection tasks in BiCI listeners. Cochlear implants, auditory protheses offered to profoundly deaf individuals for access to spoken language, retain the signal envelope (ENV), while discarding temporal fine structure (TFS) of the original acoustic input. As a result, BiCI users do not have access to low-frequency TFS cues, which have previously been shown to be crucial for sound localization in NH listeners. Instead, BiCI listeners seem to rely on ENV cues for sound localization, especially level cues. Given that NH and BiCI listeners differentially utilize ENV and TFS information, the present study aimed to investigate the usefulness of these cues for auditory motion perception. We created acoustic chimaera stimuli, which allowed us to test the relative contributions of ENV and TFS to auditory motion perception. Stimuli were either moving or stationary, presented to NH listeners in free field. The task was to track the perceived sound location. We found that removing low-frequency TFS reduces sensitivity to sound motion, and fluctuating speech envelopes strongly biased the judgment of sounds to be stationary. Our findings yield a possible explanation as to why BiCI users struggle to identify sound motion, and provide a first account of cues important to the functional aspect of auditory motion perception.

Effects of Ketamine Administration on Auditory Information Processing in the Neocortex of Nonhuman Primates.

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, exerts broad effects on consciousness and perception. Since NMDA receptor antagonists induce cognitive impairments, ketamine has been used for translational research on several psychiatric diseases, such as schizophrenia. Whereas the effects of ketamine on cognitive functions have been extensively studied, studies on the effects of ketamine on simple sensory information processing remain limited. In this study, we investigated the cortex-wide effects of ketamine administration on auditory information processing in nonhuman primates using whole-cortical electrocorticography (ECoG). We first recorded ECoG from awake monkeys on presenting auditory stimuli of different frequencies or different durations. We observed auditory evoked responses (AERs) across the cortex, including in frontal, parietal, and temporal areas, while feature-specific responses were obtained around the temporal sulcus. Next, we examined the effects of ketamine on cortical auditory information processing. We conducted ECoG recordings from monkeys that had been administered anesthetic doses of ketamine from 10 to 180 min following administration. We observed significant changes in stimulus feature-specific responses. Electrodes showing a frequency preference or offset responses were altered following ketamine administration, while those of the AERs were not strongly influenced. However, the frequency preference of a selected electrode was not significantly altered by ketamine administration over time following administration, while the imbalances in the onset and offset persisted over the course of 150 min following ketamine administration in all three monkeys. These results suggest that ketamine affects the ability to distinguish between sound frequency and duration in different ways. In conclusion, future research on the NMDA sensitivity of cortical wide sensory information processing may provide a new perspective into the development of nonhuman primate models of psychiatric disorders.

Dependency of threshold and loudness on sound duration at low and infrasonic frequencies

Many environmental sounds contain significant energy in the infrasonic and low-frequency (ISLF) ranges that have been associated with cases of annoyance and noise complaints. This study assessed the effect of sound duration on audibility and loudness of ISLF sounds. A first experiment evaluated detection thresholds for tones of 4, 16, and 32 Hz with durations up to 4000 ms. Furthermore, equal-loudness-level contours (ELCs) were obtained as function of duration up to 2000 ms. Tones of 1000 Hz were also included here. Results displayed the known pattern of general sound level decrease with increasing duration up to several hundred milliseconds. ELCs stabilized slightly earlier than thresholds, but after 1000 ms, levels remained roughly constant for both measures except for 4-Hz tones, where the decrease continued up to the longest durations tested. As 4-Hz cycles are perceptually resolved as separate pressure pulses, the authors hypothesized their duration dependence would resemble that of pulse trains. Hence, a second experiment evaluated pulse-train thresholds (1000-Hz carrier) for durations up to 4000 ms. For both pulse repetition rates of 4 and 32 Hz, threshold stabilized after 1000 ms as for tones ≥16 Hz, suggesting the continuing threshold decrease for a 4-Hz tone is specific to infrasound.