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PubMed1982

The performance of professional musicians on the seashore measures of musical talent: an unexpected finding.

During an investigation designed to explore the effects of brain lesions on musical ability in professional musicians, the Seashore Scale was used to discover whether focal damage was associated with specific impairment of any of the basic elements of musical talent. In order to obtain adequate control of the experimental group it was necessary to study a comparable group of professional musicians. For this purpose the Seashore test battery was given to 21 orchestral players. The scores obtained by these professionals were better than an estimate of the population values in only three of the six tests, pitch discrimination, rhythm and tonal memory; they were significantly poorer in the test of timbre. This unexpected finding sheds doubt on Seashore's assumptions about the requirements for high musical talent. It also raises questions on the use of the Seashore battery in certain areas of psychological research.

Adult↗
PubMed2003

Active noise control using a distributed mode flat panel loudspeaker.

A flat panel distributed mode loudspeaker (DML) has many advantages over traditional cone speakers in terms of its weight, size, and durability. However, its frequency response is uneven and complex, thus bringing its suitability for active noise control (ANC) under question. This paper presents experimental results demonstrating the effective use of panel DML speakers in an ANC application. Both feedback and feedforward control techniques are considered. Effective feedback control with a flat panel speaker could open up a whole range of new noise control applications and has many advantages over feedforward control. The paper develops a new control algorithm to attenuate tonal noise of a known frequency by feedback control. However, due to the uneven response of the speakers, feedback control is found to be only moderately effective even for this narrow-band application. Feedforward control proves to be most capable for the flat panel speaker. Using feedforward control, the sound pressure level can be significantly reduced in close proximity to an error microphone. The paper demonstrates an interesting application of the flat panel in which the panel is placed in the path of sound and effectively used to block sound transmission using feedforward control. This is a new approach to active noise control enabled by the use of flat panels and can be used to prevent sound from entering into an enclosure in the first place rather than the traditional approach of attempting to cancel sound after it enters the enclosure.

Amplifiers, Electronic↗
PubMedDate not supplied

Enhanced intensity dependence as a marker of low serotonergic neurotransmission in borderline personality disorder.

Dysfunction of central serotonergic activity has been assumed in patients with borderline personality disorder (BPD) characterized by a prominent impulsive behavioral style. Following the high serotonergic innervation of the primary auditory cortex, there is increasing evidence of the intensity dependence of auditory evoked potentials (AEP), especially the N1/P2 component, indicating serotonergic neurotransmission in animals and humans. 15 females who met the IPDE-criteria for BPD and a group of comparative healthy females (controls) completed extensive personality questionnaires which gave special regard to impulsiveness. We obtained event-related AEP through the application of various loudness stimuli. We examined the relevant N1/P2 amplitude of the tangential dipole of the auditory evoked response using dipole source analysis. The augmentation of the N1/P2 amplitude of tangential dipole source activity with rising stimulus intensity was significantly pronounced in BPD as opposed to controls, accompanied by a reduction in N1 and P2 latencies. The strong loudness dependency of AEP correlated with aspects of impulsiveness. These data imply reduced inhibiting control over cortical sensory processing in BPD. Our findings contribute a further argument to the hypothesis of low serotonergic neurotransmission in BDP and may point to a trait character of impulsiveness in this personality disorder.

Acoustic Stimulation↗
PubMed1998

Intensity coding of auditory stimuli: an fMRI study.

The effect of stimulus intensity (sound pressure level, SPL) of auditory stimuli on the BOLD response in the auditory cortex was investigated in 14 young and healthy subjects, with no hearing abnormalities, using echo-planar, functional magnetic resonance imaging (fMRI) during a verbal and a non-verbal auditory discrimination task. The stimuli were presented block-wise at three different intensities: 95, 85 and 75 dB (SPL). All subjects showed fMRI signal increases in superior temporal gyrus (STG) covering primary and secondary auditory cortex. Most importantly, the spatial extent of the fMRI response in STG increased with increasing stimulus intensity. It is hypothesized that spreading of excitation is associated with the encoding of increasing stimulus intensity levels. In addition, we found bifrontal activation supposedly evoked by the auditory-articulary loop of working memory. The results presented here should assist in the design of optimal activation strategies for studying the auditory cortex with fMRI paradigms and may help in understanding intensity coding of auditory stimuli.

Adult↗
PubMed2000

Loudness dependence of auditory evoked potentials in obsessive-compulsive disorder: a pilot study.

In recent years it has been suggested that a serotonergic dysfunction is involved in the pathogenesis of obsessive-compulsive disorder (OCD). The loudness dependence of auditory evoked potentials (AEPs) is one of the best validated indicators of the activity of the serotonin system in humans. To explore the validity of the hypothesis of a serotonergic dysfunction in OCD, the loudness dependence of AEPs of 22 medication-free OCD patients were compared with those of 22 age- and gender-matched healthy subjects. Auditory evoked N1/P2 activity to tones of increasing intensity was studied using dipole source analysis. Contrary to the hypothesis, OCD patients and healthy controls did not differ in their LDAEPs of the tangential dipole in particular, located in the primary auditory cortex and closely related to central serotonergic activity. Furthermore, no significant correlation was found between the severity of obsessive-compulsive or depressive symptoms and the loudness dependence of AEPs. These findings do not support the hypothesis of a serotonergic dysfunction in OCD patients.

Adult↗
PubMed2001

REM sleep enhancement due to rhythmical auditory stimulation in the rat.

From a physiological viewpoint, REM sleep (REMS) is a period during which homeostatic physiological regulations are impaired. In the rat, REMS occurs in two forms respectively characterized by episodes separated by long intervals (single REMS episodes) and by episodes which have short intervals and occur in sequences (REMS clusters). Since the partition of REMS in the form of either single or clustered episodes may reveal how the REMS drive and body homeostatic processes interact in the control of REMS occurrence, we have used this approach to clarify the effects of the rhythmical delivery of an auditory stimulus (1000 Hz, 63 or 88 dB, 50 ms, every 20 s), which has been previously observed by different authors to enhance REMS in the absence of a previous sleep deprivation. Stimuli were delivered to pairs of animals and triggered by the occurrence of REMS in one rat (REMS-selective stimulation), whilst the other animal received the same stimulus irrespectively of the stage of the wake-sleep cycle (REMS-unselective stimulation). The results showed that the REMS-selective stimulation did not change the overall amount of REMS, since an increase in the occurrence of REMS clusters was concomitant with a decrease in the occurrence of single REMS episodes. In contrast, under the REMS-unselective stimulation, the total amount of REMS was increased during the second day of stimulation through an increase in the duration of both types of REMS episodes. Since during the REMS-unselective stimulation 87% of the stimuli fell outside REMS (i.e., during the REMS interval), the results show that the occurrence of REMS is more consistently affected when the stimuli are delivered in a period during which homeostatic physiological regulations are fully operant.

Acoustic Stimulation↗
PubMed1991

Conditioned stimulus duration in classical trace conditioning: test of a real-time neural network model.

In classical trace conditioning, the interstimulus interval (ISI) is equal to the conditioned stimulus (CS) duration plus the trace interval (TI), the interval between CS offset and unconditioned stimulus (US) onset. The Sutton-Barto-Desmond neural-network model of classical conditioning predicts that, with a sufficiently long TI, conditioning will be faster with a CS of relatively long duration than with one of shorter duration. This prediction is illustrated with simulations and tested with the rabbit nictitating membrane response. Animals were trained with a tone CS of 350- or 700-ms duration. The TI was fixed at 300 ms, so that the ISI for the two durations was 650 or 1000 ms, respectively. Another factor in the experimental design was tone intensity (63 or 83 dB). Consistent with the model's prediction, conditioning was faster with the longer ISI, but only with the louder tone. The results have implications for computational models of classical conditioning.

Acoustic Stimulation↗
PubMed1997

Cognitive evoked potentials to speech and tonal stimuli in children with implants.

We investigated late and cognitive (mismatch negativity, P300) auditory potentials in 14 children with cochlear implants between the ages of 4 and 12 years. Length of cochlear implant use ranged from 7 to 84 months. Three types of stimulus contrasts were used: (1) a loudness contrast consisting of a 1500 Hz tone burst presented at 75 (standard) and 90 dB sound pressure level (deviant); (2) a frequency contrast consisting of a 1500 Hz tone burst (standard) and a 3000 Hz tone burst (deviant) presented at 80 dB sound pressure level; and (3) a speech contrast consisting of "heed" (standard) and "who'd" (deviant) delivered with a roving loudness paradigm involving a randomized variation of the levels of the standard and deviant stimuli. Latencies and amplitudes of components N1, P2, N2, and P3 and a mismatch negativity were measured. Overall, there were very few missing or unidentifiable components. P3 and mismatch negativity components were identified for all subjects and all stimuli. The latencies of most components were affected by stimulus type. There was a trend for longer latencies for the speech contrast compared with the loudness or frequency contrasts. This may be a reflection of the increased processing time required for the speech stimuli because of its higher complexity. There were several significant correlations between speech recognition and cognitive evoked potential latencies. These results indicate that the clinical use of cognitive evoked potentials in children with cochlear implants is feasible and informative.

Acoustic Stimulation↗
PubMed1998

The bitter with the sweet: the taste/stress/temperament nexus.

Is the tongue a window to the psyche? In rats, stress alters taste, and individual differences in taste are related to measures of emotion. The present study concerned stress-induced changes in taste and its modulation by temperament in people. College students rated saccharin's bitterness and sweetness and a tone's loudness after exposure to a mild stressor. Temperament (trait arousability, pleasure, and dominance) was assessed separately. When individual differences were ignored, stress appeared to selectively increase sensitivity to saccharin's bitterness. However, the stressor's impact was modulated by temperament: Stress nonselectively augmented stimulus magnitude ratings among highly arousable individuals; relative to high-pleasure counterparts, low-pleasure individuals gave higher bitterness ratings and lower sweetness ratings after stress. Taste does seem to provide a glimpse of the emotional life of humans and other animals and opens new avenues to the study of the biological bases of affect.

Adult↗
PubMed2001

Detection and intensity discrimination of brief tones as a function of duration by hearing-impaired listeners.

For normal listeners, difference limens for intensity (DLs) for Gaussian-shaped tone pulses are largest at medium pulse durations (corresponding to about five cycles of the tonal carrier) when the pedestals are 10 dB above threshold, either in quiet or in a pink noise background. One explanation for this is that worst performance occurs when the internal representation of the tone pulses is most compact in time and frequency, affording minimal opportunity for 'multiple looks' (Van Schijndel et al., J. Acoust. Soc. Am. 105 (1999) 3425-3435). However, the mid-duration worsening is largest for medium overall levels, suggesting an involvement of compression on the basilar membrane (BM), which is also greatest at medium levels (Baer et al., J. Acoust. Soc. Am. 106 (1999) 1907-1916). If this is so, the mid-duration worsening should be reduced when BM compression is reduced by outer hair cell damage. To test this, subjects with sensorineural hearing losses were tested using 1-kHz or 4-kHz Gaussian-shaped tone pulses, in quiet or in pink noise that raised thresholds by 10-20 dB. For subjects with mild losses, poorest performance was sometimes found for medium durations. For more severe losses, intensity DLs tended to improve monotonically or remain roughly constant with increasing duration. Performance overall tended to be better for subjects with greater hearing losses. The results are more consistent with an explanation based on BM compression than with an explanation based on multiple looks.

Acoustic Stimulation↗
PubMed2001

Frequency sensitivity range of the saccule to bone-conducted stimuli measured by vestibular evoked myogenic potentials.

Vestibular evoked myogenic potentials (VEMPs) occurring in cervical muscles after intense sound stimulation conducted by air or bone are thought to be a polysynaptic response of otolith-vestibular nerve origin. We report the results of an experiment to investigate whether acoustic stimulation of the saccule by bone conduction produces VEMPs in which response amplitudes are somewhat sensitive to stimulus frequency, as appears to be the case with air-conducted stimuli. Prior to this we investigated the effect of stimulation repetition rate on bone-conducted VEMPs (B-VEMPs) at stimulus frequencies of 200 and 400 Hz with five different repetition rates (5, 10, 20, 40, and 80 Hz). B-VEMPs were recorded from 12 normal hearing subjects in response to bone-conducted 70 dB (normal hearing level), 10-ms tone bursts (rise/fall time=1 ms and plateau time=8 ms) at frequencies of 100, 200, 400, 800, 1600 and 3200 Hz. Our study showed that B-VEMP amplitudes were highest at 10 Hz but decreased as the repetition rate increased. B-VEMP response amplitudes were found to be maximal for stimulus frequencies from 200 to 400 Hz. This response may contribute to the perception of loud sounds.

Acoustic Stimulation↗
PubMed2002

Addition of noise enhances neural synchrony to amplitude-modulated sounds in the frog's midbrain.

The ability of 109 single units in the midbrain acoustic centre of frogs (Rana ridibunda, Rana temporaria) to reproduce 10%, 20 Hz sinusoidal amplitude modulation of a long-duration characteristic frequency tone was studied. The sinusoidal modulation was presented either in isolation or summed with a low-frequency (0-50 Hz) noise. Recordings were obtained in the adapted state. The magnitude of the 20 Hz periodic response component was estimated by means of the synchronisation coefficient and the amplitude of the sine modulation of the instantaneous spike rate. In many units, addition of noise modulation produced considerable enhancement of both the mean discharge rate and the discharge rate synchronised to the 20 Hz amplitude modulation. This enhancement phenomenon is interpreted in the context of stochastic resonance theory.

Acoustic Stimulation↗
PubMed2002

Asymmetric hemodynamic responses of the human auditory cortex to monaural and binaural stimulation.

Applying whole-head functional magnetic resonance imaging (fMRI) in 11 neurologically intact subjects, hemodynamic responses to mon- or binaurally presented auditory stimuli were measured. To expand on previous studies in this research area, we used tones and consonant-vowel (CV) syllables. In one group of subjects (n=6) the perceived loudness of the monaurally presented stimuli were adjusted so that they matched the loudness of the binaurally presented stimuli. In a second group (n=5) no loudness adjustment was performed, thus the monaural stimuli were perceived less loud ( approximately 10 dB) than the binaural stimuli. These extensions allowed us to test whether CV syllables and tones produce different contralaterality effects (stronger hemodynamic responses in the auditory cortex contralateral to the stimulated ear) and whether binaural stimulation results in stronger activations in the auditory areas than during both monaural stimulation conditions (binaural summation) independent of loudness influences. In summary, we obtained the following findings: (1) strong contralaterality effects during monaural acoustic stimulation in the posterior superior temporal gyrus (STG) comprising the planum temporale and the dorsal bank of the superior temporal sulcus to CV syllables and tones; (2) the hemodynamic responses to contralaterally presented stimuli (during the monaural conditions) were mostly stronger than those to binaurally presented CV syllables; (3) there was no interaction between stimulus type and the size of the contralaterality effect; (4) there was no indication of binaural summation, rather we found stronger hemodynamic responses to the sum of both monaural stimulations (right and left ear) than to binaural stimulation in all auditory areas; (5) there were generally stronger hemodynamic responses to CV syllables than to tones in the posterior STG, while the hemodynamic responses to tones were stronger in the anterior part of the STG (temporal pole); and finally (6) there was no general difference in terms of hemodynamic response in the auditory cortex between the two groups when receiving either loudness-matched or non-loudness-matched monaural stimulation. These findings are discussed in the context of the underlying neurophysiological mechanisms, the peculiarities of functional fMRI, and the direct access and callosal relay models of hemispheric lateralization.

Acoustic Stimulation↗
PubMed2003

The perceptual effects of interphase gap duration in cochlear implant stimulation.

The most common current pulse shape used for cochlear implants is a biphasic rectangular pulse. The interphase gap (IPG) is the duration of the zero-current portion which lies between the two phases. It is known from single-nerve studies in animals that, as the IPG decreases, the biphasic pulse becomes less efficient in activating the nerve cell. Thus, it can be predicted that stimulation using smaller IPGs will necessitate the use of higher currents to maintain the loudness required by the cochlear implantee. The development of contemporary processing schemes commonly involves the maximization of the rate parameter, and to achieve this in sequential pulsatile stimulation, the IPG as well as the pulse phase duration must be minimized. This experiment investigated the effect of IPG on loudness in eight cochlear implantees who use the CI24 implant manufactured by Cochlear Ltd. An exponential increase in current level was required to maintain equal loudness when IPG is reduced from 100 to 45 and 8.4 micros. The effect of IPG was greater at lower levels, was greater for shorter pulse durations (26 micros compared to 52 micros), and was not significantly different for the rates (1 kHz or 4 kHz) tested.

Cochlear Implants↗
PubMed2003

Noise improves suprathreshold discrimination in cochlear-implant listeners.

The present study aimed to examine the effect of noise on vowel-like suprathreshold discrimination in cochlear-implant listeners. The task was to detect an increment in level at the middle harmonic (400 Hz) in the background of a seven-harmonic complex from 100 to 700 Hz in 100-Hz steps. The task was performed in the absence (control) and presence of a white noise presented over a 20-35-dB range from inaudible to loud. The present result shows that discrimination of suprathreshold harmonic stimuli was significantly enhanced, particularly at the soft signal level, with suprathreshold noise. This result suggests that tuning of the noise level is required to optimize performance of different tasks in cochlear implants.

Adult↗
PubMed1998

Cochlear mechanisms of frequency and intensity coding. II. Dynamic range and the code for loudness.

Our preceding paper described SPL-dependent changes in the shape of transfer functions recorded from inner and outer hair cells as well as supporting cells, in the 500-2500 Hz regions of the Mongolian gerbil cochlea. As SPL was increased, large shifts were observed in the peak of the transfer function. A strongly compressive nonlinearity was also observed at CF. This paper examines the data from the perspective of intensity coding in the auditory periphery. Based on the data, we offer a new explanation for the mechanisms underlying the different dynamic ranges of low and high threshold auditory neurons. We also find that, for pure tone stimuli, the growth of excitation at the characteristic place saturates rapidly, and cannot encode the wide dynamic range of loudness. The data are analyzed to explore other excitation pattern candidates for loudness coding. The growth of the peak of the IHC transfer function, as well as the growth of the response area, have been found to be linearly related to loudness growth over most of its dynamic range. Implications of the data for auditory intensity coding are discussed.

Animals↗
PubMed1999

Distributed representation of spectral and temporal information in rat primary auditory cortex.

Modulations of amplitude and frequency are common features of natural sounds, and are prominent in behaviorally important communication sounds. The mammalian auditory cortex is known to contain representations of these important stimulus parameters. This study describes the distributed representations of tone frequency and modulation rate in the rat primary auditory cortex (A1). Detailed maps of auditory cortex responses to single tones and tone trains were constructed from recordings from 50-60 microelectrode penetrations introduced into each hemisphere. Recorded data demonstrated that the cortex uses a distributed coding strategy to represent both spectral and temporal information in the rat, as in other species. Just as spectral information is encoded in the firing patterns of neurons tuned to different frequencies, temporal information appears to be encoded using a set of filters covering a range of behaviorally important repetition rates. Although the average A1 repetition rate transfer function (RRTF) was low-pass with a sharp drop-off in evoked spikes per tone above 9 pulses per second (pps), individual RRTFs exhibited significant structure between 4 and 10 pps, including substantial facilitation or depression to tones presented at specific rates. No organized topography of these temporal filters could be determined.

Acoustic Stimulation↗