Trains Of Tone Bursts Research Articles

Quick Estimation of Minimum Hearing Levels Using a Binaural Multifrequency Stimulus Paradigm: Proof of Concept.

Objective estimation of minimum hearing levels using auditory brainstem responses (ABRs) elicited by single frequency tone-bursts presented monaurally is currently considered the gold standard. However, the data acquisition time to estimate thresholds (for both ears across four audiometric frequencies) using this method usually exceeds the sleep time (ranging between 35 and 49 minutes) in infants below 4 months, thus providing incomplete information of hearing status which in turn delays timely clinical intervention. Alternate approaches using faster rate, or tone-burst trains have not been readily accepted due to additional hardware and software requirements. We propose here a novel binaural multifrequency stimulation paradigm wherein several stimuli of different frequencies are presented binaurally in an interleaved manner. The rationale here is that the proposed paradigm will increase acquisition efficiency, significantly reduce test time, and improve accuracy by incorporating an automatic wave V detection algorithm. It is important to note that this paradigm can be easily implemented in most commercial ABR systems currently used by most clinicians. Using this binaural multifrequency paradigm, ear specific ABRs were recorded in 30 normal-hearing young adults to both tone-bursts, and narrow-band (NB) iChirps at 500, 1000, 2000, and 4000 Hz. Comparison of ABRs elicited by tone-bursts and narrow-band chirps allowed us to determine if NB iChirps elicited a more robust wave V component compared with the tone-bursts. ABR data were characterized by measures of minimum hearing levels; wave V amplitude; and response detectability for two electrode configurations (high forehead-C7; and high forehead-linked mastoids). Consistent with the research literature, wave V response amplitudes were relatively more robust for NB iChirp stimuli compared with tone-burst stimuli. The easier identification and better detectability of wave V for the NB iChirps at lower stimulus levels contributed to their better thresholds compared with tone-burst elicited responses. It is important to note that binaural multifrequency hearing levels close to minimum hearing levels were determined in approximately 22 minutes using this paradigm-appreciably quicker than the 45 to 60 minutes or longer time required for threshold determination using the conventional single frequency method. Our novel and simple paradigm using either NB iChirps or tone-bursts provides a reliable method to rapidly estimate the minimum hearing levels across audiometric frequencies for both ears. Incorporation of an automatic wave V detection algorithm increases objectivity and further reduce test time and facilitate early hearing identification and intervention.

Improving acquisition time of the frequency-specific auditory brainstem response through simultaneous independently random toneburst sequences

The frequency-specific auditory brainstem response (ABR) is an objective electroencephalographic (EEG) method for estimating auditory thresholds when behavioral thresholds are not attainable, primarily in infants and toddlers. It is recorded by repeatedly presenting brief, band-limited tonebursts and averaging the scalp potential response. In a typical ABR evaluation, measurements are made at multiple intensities, at multiple frequencies, and in both ears, leading to a large combinatorial space and long test times. Here, we present a method of recording the responses at five frequencies in both ears simultaneously, along with preliminary data demonstrating its effectiveness. We created ten toneburst trains—five octave frequencies (500–8000 Hz) by two ears—for simultaneous presentation. Importantly, the toneburst timing for each train was dictated by an independent random process, rather than being periodic. Independent sequences allow separate computation of the ABR to each of the toneburst trains as the cross-correlation of its timing sequence and the EEG recording. Early results suggest substantial improvements in recording time, particularly at lower stimulus intensities. It also appears that cochlear spread of excitation—a problem at high intensities—is mitigated by our method. This improvement in place specificity is predicted by modeling of auditory nerve activity.

Mixing of ultrasonic Lamb waves in thin plates with quadratic nonlinearity

This paper investigates the propagation of Lamb waves in thin plates with quadratic nonlinearity by one-way mixing method using numerical simulations. It is shown that an A0-mode wave can be generated by a pair of S0 and A0 mode waves only when mixing condition is satisfied, and mixing wave signals are capable of locating the damage zone. Additionally, it is manifested that the acoustic nonlinear parameter increases linearly with quadratic nonlinearity but monotonously with the size of mixing zone. Furthermore, because of frequency deviation, the waveform of the mixing wave changes significantly from a regular diamond shape to toneburst trains.

Experiment and FEM study of one-way mixing of elastic waves with quadratic nonlinearity

This paper investigates frequency deviation during imperfect resonant conditions through FEM simulations and experimental measurements using a one-way mixing technique. Waveforms of resonant waves are determined to change significantly from a diamond shape to certain toneburst trains as frequency deviation increases. The critical limit of frequency deviation for aluminum is obtained within ±7%. In the case of quasi-collinear mixing, scanning experimental results show that the received amplitude of the mixing wave increases with increasing mixing distance, and a special angle of the mixing wave in FEM simulations is found to explain this trend.

Attention orienting dysfunction with preserved automatic auditory change detection in migraine

ObjectiveTo investigate automatic event-related potentials (ERPs) to an auditory change in migraine patients. MethodsAuditory ERPs were recorded in 22 female patients suffering from menstrually-related migraine and in 20 age-matched control subjects, in three sessions: in the middle of the menstrual cycle, before and during menses. In each session, 200 trains of tone-bursts each including two duration deviants were presented in a passive listening condition. ResultsIn all sessions, duration deviance elicited a mismatch negativity (MMN) showing no difference between the two groups. However, migraine patients showed an increased N1 orienting component to all incoming stimuli and a prolonged N2b to deviance. They also presented a different modulation of P3a amplitude along the menstrual cycle, which tended to normalise during migraine attacks. None of the studied ERP components showed a default of habituation. ConclusionsThis passive paradigm highlighted increased automatic attention orienting to auditory changes but normal auditory sensory processing in migraineurs. SignificanceOur observations suggest normal auditory processing up to attention triggering but enhanced activation of attention-related frontal networks in migraineurs.

Classification of selective attention to auditory stimuli: Toward vision-free brain–computer interfacing

Brain–computer interface (BCI) is a developing, novel mode of communication for individuals with severe motor impairments or those who have no other options for communication aside from their brain signals. However, the majority of current BCI systems are based on visual stimuli or visual feedback, which may not be applicable for severe locked-in patients that have lost their eyesight or the ability to control their eye movements. In the present study, we investigated the feasibility of using auditory steady-state responses (ASSRs), elicited by selective attention to a specific sound source, as an electroencephalography (EEG)-based BCI paradigm. In our experiment, two pure tone burst trains with different beat frequencies (37 and 43Hz) were generated simultaneously from two speakers located at different positions (left and right). Six participants were instructed to close their eyes and concentrate their attention on either auditory stimulus according to the instructions provided randomly through the speakers during the inter-stimulus interval. EEG signals were recorded at multiple electrodes mounted over the temporal, occipital, and parietal cortices. We then extracted feature vectors by combining spectral power densities evaluated at the two beat frequencies. Our experimental results showed high classification accuracies (64.67%, 30 commands/min, information transfer rate (ITR)=1.89bits/min; 74.00%, 12commands/min, ITR=2.08bits/min; 82.00%, 6 commands/min, ITR=1.92bits/min; 84.33%, 3 commands/min, ITR=1.12bits/min; without any artifact rejection, inter-trial interval=6s), enough to be used for a binary decision. Based on the suggested paradigm, we implemented a first online ASSR-based BCI system that demonstrated the possibility of materializing a totally vision-free BCI system.

Responses of neurons in the rat's dorsal cortex of the inferior colliculus to monaural tone bursts

Responses to contralaterally presented tone bursts were recorded from single auditory neurons in the rat's dorsal cortex of the inferior colliculus (ICd). Most of these neurons either had low level of firing or generated no action potentials in the absence of sound stimulation. In response to tone bursts, about half of the ICd neurons fired at the onset while about 40% of the neurons fired over the entire duration of the sounds. The remaining ICd neurons fired transiently at the offset or both the onset and the offset of the sounds. In comparison with neurons in the central nucleus of the inferior colliculus, neurons in the ICd had much longer first spike latencies and much larger magnitudes of jitter in the first spike latency. Many neurons in the ICd displayed complex frequency tuning properties. No strong correlation was revealed between the characteristic frequency of a neuron and its location along an axis oriented from a rostrodorsolateral to a caudoventromedial part of the ICd. There are neurons in the ICd showing stimulus-specific adaptation. For these neurons, presentations of a tone burst elicited stronger responses when these presentations were embedded in a train of tone bursts with various different frequencies than clustered in a block. Neurons with stimulus-specific adaptation displayed phasic firing at the onset of a tone burst. Our results suggest that the ICd is important for detecting novel sounds in the acoustic environment.

Informational masking release in children and adults

This study assessed informational masking and utilization of cues to reduce that masking in children aged 4-9 years and in adults. The signal was a train of eight consecutive tone bursts, each at 1 kHz and 60 ms in duration. Maskers were comprised of a pair of synchronous tone-burst trains, with randomly chosen frequencies spanning 200-5000 Hz, with a protected region 851-1175 Hz. In the reference condition, maskers were eight bursts in duration, with a fixed frequency within intervals. Experiment 1 tested two monotic masking release conditions: within-interval randomization of masker burst frequency and the introduction of leading masker bursts. Experiment 2 examined masking release in which the signal was presented to one ear and masking components were presented to both ears (masker components in the contralateral ear were 10 dB higher than those in the ipsilateral ear). Both adults and children demonstrated a significant informational masking effect, with children showing a larger effect on average. Both groups also showed significant release from masking in the two monotic conditions, although children received somewhat less benefit from the masking release cues. The binaural condition supported a moderate release from informational masking in adults, but resulted in increased informational masking in children.

Physiological overshoot and the compound action potential

The sensitivity of the compound action potential (CAP) of the auditory nerve of the Mongolian gerbil ( Meriones unguiculatus) to an added signal was studied as a function of the state of adaptation to a masker. The masker consisted of a train of tone bursts. A signal was added to one of the bursts and the threshold for detecting the signal was determined using a two-interval forced-choice technique. With a signal at the same frequency as the masker, there was little or no change in threshold with increasing adaptation to the masker, i.e., with the signal applied at masker onset or later on in the train. With a signal at a different frequency, considerably higher thresholds were obtained in the unadapted state than in the adapted state, a situation that appeared to resemble psychophysical overshoot phenomena. However, the interpretation of this result was complicated by the observation that the CAP response to a two-frequency stimulus is a sum of two slightly desynchronized waveforms arising from different cochlear regions. Synchronizing the two waveforms reduced the ‘overshoot’, but still resulted in higher thresholds in the unadapted state. The differences in threshold are accounted for by considering the changing signal-to-noise ratios at different states of adaptation. Possible relationships to psychophysically observed overshoot are discussed.

Inactivation of the DSCF area of the auditory cortex with muscimol disrupts frequency discrimination in the mustached bat.

1. The Jamaican mustached bat uses a biosonar signal (pulse) with eight major components: four harmonics each consisting of a long constant frequency (CF1-4) component followed by a short frequency-modulated (FM1-4) component. While flying, the bat adjusts the frequency of its pulse so as to maintain the CF2 of the Doppler-shifted echo at a frequency to which its cochlea is very sharply tuned. This Doppler shift (DS) compensation likely is mediated or influenced by the Doppler-shifted CF (DSCF) processing area of the primary auditory cortex, which only represents frequencies in the range of echo CF2s (60.6 to 62.3 kHz when the "resting" frequency of the CF2 is 61.0 kHz). 2. We trained four bats to discriminate between different trains of paired tone bursts that mimicked a bat's pulse CF2 and the accompanying echo CF2. The frequency of these CF2s ranged between 61.0 and 64.0 kHz. A discriminated shock avoidance procedure response was employed using a leg flexion. For one stimulus, the S+, the pulse and echo CF2s were the same frequency (delta f = 0, i.e., no Doppler shift). A leg flexion during the S+ turned off both the S+ and the scheduled shock. For a second stimulus, the S-, the echo CF2 was 0.05, 0.1, 0.3, 0.5, or 2.0 kHz higher than the pulse CF2. A delta f of 0.05 kHz was a frequency difference of 0.08%. No shock followed the S-, and leg flexions had no consequences. Correct responses consisted of a leg flexion during the S+ and no flexion during the S-; these responses were added together to compute the percentage of correct responses. When a bat correctly responded at better than 75% for all the delta f s, muscimol, a potent agonist of gamma-aminobutyric acid, was bilaterally applied to inactivate the DSCF area. Performance on each delta f discrimination was then measured. 3. Initial attempts to condition the bats to flex their legs to the CF tones mimicking part of the natural pulses and echoes failed. When broad-band noise bursts were substituted, however, the conditioned response was rapidly established. The noise band-width was gradually reduced and then replaced with the CF tones. Discrimination training with the tone burst trains then commenced. Throughout this procedure, the bats maintained their responding to the stimuli. The bats typically required approximately 20-30 sessions to perform consistently (> or = 75% correct responses) a discrimination involving a 2 kHz delta f.(ABSTRACT TRUNCATED AT 400 WORDS)

猫のか牛神経核ニューロンの短音列に対する応答

Although both posteroventral cochlear nucleus (PVCN) and dorsal cochlear nucleus (DCN) are innervated by the descending branch of auditory nerve fibers, their intrinsic morphological organizations are so different that their physiological roles are expected to be different in signal processing. Temporal information coding of acoustic signals in the cochlear nucleus was examined by using stimuli of "tone-burst-trains (TBT)". Responses of cochlear nucleus neurons of anesthetized cats were recorded either intracellularly or extracellularly. Responses of the neurons to TBT stimuli were classified into "adaptive type" and "non-adaptive type". The "adaptive type" neurons were mainly recorded from PVCN. Responses of these neurons to TBT stimuli decayed exponentially, because of short-term adaptation, in the subsequent tone-bursts. These neurons faithfully preserve the adaptative behavior of auditory nerve fibers. On the contrary, the "non-adaptive type" neurons were mainly found in DCN. They showed variety of responses to TBT stimuli including facilitation, disinhibition and inhibition depending on duration and/or interval of tone-bursts. Our results suggest that some "non-adaptive type" neurons, showing facilitative and/or inhibitory responses to TBT stimuli, act as temporal filters that extract temporal information from acoustic signals.

An interactive toolset for characterizing complex neural systems

A set of two computer programs is described which enable the following functions: 1. (1) High-speed data acquisition from up to eight recording channels with presentation of uniform or quasi-random stimulus trains on one or two stimulus channels. 2. (2) On-line computation and display of averaged responses on all recording channels evoked by both stimulus channels. 3. (3) Computation and display of averaged evoked potentials and functional power series (FPS) through third order for characterization of system nonlinearities. 4. (4) Computation and display of stimulated responses to arbitrarily selected stimulus trains using a previously computed FPS. Both programs are implemented in FORTRAN, include on-line help, interactive and batch processing facilities and produce extensive graphics output according to the Tektronix 4010 protocol. Their initial implementation was on an LSI-II microcomputer using TSX + extensions to RT11. Additional capabilities and speed have been gained by porting the analysis routine to the Apollo workstation environment. To date these programs have been used to study the following: 1. (1) The somatosensory system in the human using dual random trains presented to the median and ulnar nerves. 2. (2) Cognitive processing in the human (normals and first-break schizophrenics) using both uniform (P300 paradigm) and dual random trains of tone bursts with the subject either counting or pressing a lever in response to tones with a specific pitch. 3. (3) The network properties of the rabbit hippocampus (both in vivo and in vitro preparations) using random train simulation of the intrinsic pathways.

The Acoustic Reflex Pattern Studied by the Averaging Technique

The acoustic reflex threshold and its pattern in response to stimuli of different intensities, were investigated by means of the signal-averaging technique in 20 normal, 20 sensorineural-impaired and 10 successfully stapedectomized ears. Trains of tone bursts between 110 and 0 dB HL were used. The frequencies tested were 500, 1 000, 2 000 and 4 000 Hz. In all normal subjects, the pattern of the acoustic reflex for stimuli between 110 and 100 dB HL was biphasic with an initial positive plateau followed by a longer negative one. For stimuli below 80 dB HL, the pattern of the reflex was monophasic with a single positive peak. In the sensorineural-impaired ears, the same double pattern of the waveform was obtained. In the stapedectomized ears, no compliance changes were observed for any sound stimuli. By the averaging technique, the difference between the acoustic reflex threshold and the auditory threshold was found to be between 7.5 and 32.5 dB, in normal and sensorineural-impaired ears.

Average‐rate, fundamental and harmonic‐distortion components of responses of cochlear nerve fibers to single‐frequency tone bursts: Comparison with an exponential model

The effects of stimulus envelope on the response characteristics of cochlear nerve fibers can be studied with a class of stimuli of the form p(t) = ex(t) sin (ωt). In this study, the modulating function eg(t) was chosen to produce a train of tone bursts of specified duty cycle and rise/fall times. The technique of Fourier analysis of period histograms described by Kim et al. (preceding abstract) has been extended to handle variations in response components R0,R1, and θ1 as a function of time both within and between each tone burst in a train of bursts. Using tone bursts of 320 ms duration and 20 ms rise/fall times with a duty cycle of 21% we have observed that, during the course of a tone burst: (1) both R0 and R1 rapidly reach a peak value and then decline over the following 50–100 ms to quasi‐steady—state values; (2) the time courses of R0 and R1 during a tone burst are almost identical in shape, i.e., the ratio, R1/R0, reaches its maximum value rapidly and remains constant throughout the duration of a tone burst despite noticeable fluctuations in R1 and R0; (3) the fundamental phase θ1, is constant throughout the total duration of a tone burst; (4) R1R0 saturates at lower sound pressure levels (SPL) than either R0 or R1; (5) the shapes of R0 and R1 vs SPL curves change substantially and progressively for successive periods during the onset portion of the response; and (6) in some cases, the R0 and R1 versus SPL curves for individual periods during the first 12–20 ms following tone burst onset show pronounced nonmonotonic behavior with maxima occurring at as low as 50 dB re 20 μN/m2.

Differential sensitivity to frequency and intensity in songbirds

Frequency- and intensity-difference limens were measured in two passerine species, the red-wing blackbird (Agelaius Phoeniceus) and the brown-headed cowbird (Molothrus Ater). Operant conditioning techniques which we described previously were employed. The techniques made use of key pecks as observing and report responses. Birds were reenforced with food for reporting changes in frequency or intensity in an ongoing train of tone bursts. Smallest Weber fractions were obtained at 4 kHz where the mean JND was 30 Hz or Δf/f=0.0075. The mean value of Δf/f was 0.015 at 1 kHz and 0.02 at 8 kHz. Birds were more sensitive to upward frequency shifts than to downward shifts at 1 and 2 kHz. Mean intensity JND's were 2.5 dB for a 1-kHz tone at 50 dB SL and 5.4 dB for a 20-dB-SL tone. [This work was supported by a grant from NINCDS.]

Frequency-difference thresholds in Chinchilla using conditioned avoidance techniques

Chinchillas were trained to discriminate or detect pure-tone frequency differences using shock-avoidance procedures. Two psycho-physical paradigms were investigated. Initial attempts at determining frequency-difference thresholds utilized a complex discrimination paradigm. Although discriminations of large frequency differences were obtained from Chinchilla with adequate success, discriminations of very small frequency differences could not be trained. Therefore, determinations of frequency-difference thresholds were not possible with this complex discrimination paradigm. A second relatively simple detection paradigm, involving the detection of frequency alternation in an on-going train of tone bursts, proved to be a somewhat more successful technique. Frequency alternation detection was quickly learned by the Chinchillas and frequency-difference thresholds were obtained with an adaptive sequential procedure. Those frequency-difference thresholds are comparable to frequency-difference thresholds obtained in other animal species by previous investigators. Some of the difficulties in maintaining reliable behavior in Chinchillas with shock avoidance techniques are discussed. [Work supported by DRF grant.]

Intensity discrimination in a rapid sequence of tone bursts.

Listeners monitored a rapid series of tone bursts to detect intensity increments in a 1000-Hz tone presented in continuous white noise. The data were analyzed using TSD statistics and suggest that performance was close to that observed in more conventional paradigms. Possible violations of TSD assumptions are discussed and it is concluded that TSD may be used to analyze the performance of people listening to rapid trains of tone bursts as well as when discrete trials are used.

Time sharing auditory perception: effect of stimulus duration.

Listeners heard trains of tone bursts dichotically, one ear receiving bursts of one frequency, the other bursts of another. Listeners were required to detect increments in intensity, which might occur in either ear separately or in both ears at the same moment. Increasing the duration of the tone bursts was found to improve single-channel detectability in the classical way but to have relatively little effect on the detection of simultaneous targets.