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PubMed2001

How do tympanic-membrane perforations affect human middle-ear sound transmission?

Although tympanic-membrane (TM) perforations are common sequelae of middle-ear disease, the hearing losses they cause have not been accurately determined, largely because additional pathological conditions occur in these ears. Our measurements of acoustic transmission before and after making controlled perforations in cadaver ears show that perforations cause frequency-dependent loss that: (1) is largest at low frequencies; (2) increases as perforation size increases; and (3) does not depend on perforation location. The dominant loss mechanism is the reduction in sound-pressure difference across the TM. Measurements of middle-ear air-space sound pressures show that transmission via direct acoustic stimulation of the oval and round windows is generally negligible. A quantitative model predicts the influence of middle-ear air-space volume on loss; with larger volumes, loss is smaller.

Ear, Middle↗
PubMed1998

Characteristics of the acoustic distortion product 2f2-f1 from the normal human ear.

The aim of this study was to determine the basic properties of the 2f2-f1 distortion product otoacoustic emissions (DPOEs) in 36 normally hearing subjects and to compare their characteristics with those of the 2f1-f2 DPOEs. The influence of stimulation parameters on 2f2-f1 DPOE behaviour was examined: i) stimulation levels varied from 40 to 70 dB sound pressure level in 10 dB steps; and ii) two values of the f2/f1 ratio were used (1.12 and 1.22). The prevalence and the level of the 2f2-f1 DPOEs depended on three parameters: f2 frequency, stimulation level and f2/f1 ratio. The results showed many differences between the characteristics of 2f1-f2 and 2f2-f1 DPOEs, probably due to their being generated by different mechanisms. Thus, the 2f2-f1 DPOEs may provide different information about the cochlear status and could be of clinical interest.

Acoustic Stimulation↗
PubMed2003

Binaural beat induced theta EEG activity and hypnotic susceptibility: contradictory results and technical considerations.

The present study offered a constructive replication of an earlier study which demonstrated significant increases in theta EEG activity following theta binaural beat (BB) entrainment training and significant increases in hypnotic susceptibility. This study improved upon the earlier small-sample, multiple-baseline investigation by employing a larger sample, by utilizing a double-blind, repeated-measures group experimental design, by investigating only low and moderate susceptible participants, and by providing 4 hours of binaural beat training. With these design improvements, results were not supportive of the specific efficacy of the theta binaural beat training employed in this study in either increasing frontal theta EEG activity or in increasing hypnotic susceptibility. Statistical power analyses indicated the theta binaural beat training to be a very low power phenomenon on theta EEG activity. Furthermore, we found no significant relationship between frontal theta power and hypnotizability, although the more hypnotizable participants showed significantly greater increases in hypnotizability than the less hypnotizables. Results are discussed within the context of participant selection and classification factors, technical considerations in the presentation of TBB training, and theta blocking.

Adolescent↗
PubMed1982

Illusory changes in a sound source and outflow theory.

Two experiments, with a total of 220 Ss, were conducted to investigate the possibility of illusory movement of a sound source. In Experiment 1 intensity level (from 10 to 60 db SPL) and frequency of an auditory sound (from 1000 to 5000 Hz) were varied while the Ss head was stabilized with a head rest; in Experiment 2, intensity and frequency were also varied while the S's head was free to move. When head position was fixed, error signal variables such as intensity had no effect on the frequency of illusory direction changes of a sound source. However, when the head position was not fixed, increasing the intensity of the sound source significantly decreased the number of reported illusory direction changes. In addition, in both experiments, illusory changes of intensity were experienced by Ss, and increasing the intensity of the sound source also decreased this illusion. The results were interpreted in the context of an error signal and noise model of autokinetic effects, and the implications for the perception of auditory localization and movement of a sound source were discussed.

Auditory Perception↗
PubMed1995

Evidence for frequency-dependent and frequency-independent components in increasing- and decreasing-loudness aftereffects.

Listening to a decreasingly intense tone leads to increasing loudness in a subsequent steady tone. Conversely, listening to an increasingly intense tone leads to decreasing loudness in a subsequent steady tone. Measurement entails a test stimulus changing in sound level to null any aftereffect, so that loudness is perceived as steady. Previous studies have shown that the aftereffects are frequency dependent: Carrier frequencies of adapting and test stimuli must be closely matched for the greatest aftereffects. In the present study, frequency-independent components were also indicated: Despite separation between adapting and test frequencies of up to two octaves, measurements always differed after decreasing and increasing sound-level adaptation, such that frequency functions for the two directions of adaptation never crossed. According to evidence from other negative adaptation effects in the auditory modality, explanation of the present aftereffects requires at least two mechanisms: Frequency-dependent components may reflect sensory processing, whereas frequency-independent components may be nonsensory in origin.

Attention↗
PubMed1996

Separating the effects of alertness from the effects of encoding in a pitch-imagery task.

The facilitatory effects of auditory imagery have often been attributed to priming. However, the facilitatory effects of a prime on subsequent processing can be separated into effects related to specific perceptual processes, such as encoding, and effects related to more general processes, such as alertness. Whereas research on auditory imagery has focused on code-activated facilitation, the role of alertness in image-induced facilitation has been largely presumed rather than empirically investigated. Therefore, a study was designed to isolate the facilitatory effects of alertness from those of encoding. The results show that the nonspecific alerting effects of auditory imaging were quite extensive--a nearly 78-ms decrease in reaction time--compared with the effects of encoding.

Acoustic Stimulation↗
PubMed2003

Rate limits in sensorimotor synchronization with auditory and visual sequences: the synchronization threshold and the benefits and costs of interval subdivision.

Synchronization of finger taps with an isochronous event sequence becomes difficult when the event rate exceeds a certain limit. In Experiment 1, the synchronization threshold was reached at interonset intervals (IOIs) above 100 ms with auditory tone sequences (in a 1:4 tapping task) but at IOIs above 400 ms with visual flash sequences (1:1 tapping). Using IOIs above those limits, the author investigated in Experiment 2 the reduction in the variability of asynchronies that tends to occur when the intervals between target events are subdivided by additional identical events (1:1 vs. 1:n tapping). The subdivision benefit was found to decrease with IOI duration and to turn into a cost at IOIs of 200-250 ms in auditory sequences and at IOIs of 450-500 ms in visual sequences. The auditory results are relevant to the limits of metrical subdivision and beat rate in music. The visual results demonstrate the remarkably weak rhythmicity of (nonmoving) visual stimuli.

Adult↗
PubMed1985

Utility of the Seashore Tonal Memory Test in neuropsychological assessment.

This study assessed the diagnostic utility of the Seashore Tonal Memory Test in detecting and localizing cerebral lesions. A group of 238 subjects with focal or diffuse cerebral lesions and a group of 112 normal comparison subjects were administered the Seashore Tonal Memory Test and the Halstead-Reitan Battery. All brain-damaged subgroups did significantly worse than the normal group on the Tonal Memory Test. Patients with right-hemisphere lesions were more impaired on this test than were those with left-hemisphere lesions. In contrast, Seashore Rhythm Test scores were not significantly different for groups with right- versus left-hemisphere lesions. Tonal Memory performance was not found to be related to more precise location of structural lesions within the right hemisphere. Step-wise discriminate function analyses indicated that the Tonal Memory Test adds to the Halstead-Reitan Battery in discriminating left-hemisphere from right-hemisphere lesions and that, for this purpose, it was a better discriminator than all but one of the individual tests currently in the battery.

Adult↗
PubMed2005

Remote capture of human voice acoustical data by telephone: a methods study.

In this pilot study we sought to determine the reliability and validity of collecting speech and voice acoustical data via telephone transmission for possible future use in large clinical trials. Simultaneous recordings of each participant's speech and voice were made at the point of participation, the local recording (LR), and over a telephone line using a dedicated in-line computerized interactive voice recording system, the remote recording (RR). All voice recordings were made from our laboratory telephone located in Groton, Connecticut to the RR system located in Madison, Wisconsin. All data points were compared on a measure-by-measure basis between the LR and RR recordings. The results suggest that both measures of frequency excursion and of speech motor timing are reliably captured over the telephone. Results are discussed in terms of specific acoustic measures that may be useful and accurately measured via telephone transmission, for examining disease severity and pharmacological intervention for use in a large-scale clinical trial.

Adult↗
PubMed2005

Episodic temporal generalization: a developmental study.

Groups of 5-year-olds, 10-year-olds, and adults completed either an episodic temporal generalization task, in which no stimuli were repeated, or a repeated standard temporal generalization task, in which there was a fixed standard that was repeated on every trial. Significant developmental improvements were found on both tasks. In both tasks, gradients of performance over two different stimulus ranges superimposed well when plotted on the same relative scale. Performance was similar for the adults and 10-year-olds across tasks, but the 5-year-olds performed better on the repeated standard task. These findings suggest that perceptual processes are a source of scalar variability in timing, and that there are developmental changes in levels of such variability.

Adult↗
PubMed2006

Residual inhibition functions in relation to tinnitus spectra and auditory threshold shift.

CONCLUSIONS: Psychoacoustic functions relating the depth and duration of tinnitus suppression ('residual inhibition') to the center frequency of band-passed noise masking sounds appear to span the region of hearing loss, as do psychoacoustic measurements of the tinnitus spectrum. The results (1) suggest that cortical map reorganization induced by hearing loss is not the principal source of the tinnitus sensation and (2) provide a necessary baseline for optimizing residual inhibition in individual cases. OBJECTIVE: To measure residual inhibition functions and tinnitus spectra using sounds spanning the region of hearing loss. MATERIALS AND METHODS: Three subject-driven, computer-based tools were developed and applied to measure psychoacoustic properties of tinnitus and residual inhibition in 32 subjects with chronic tonal, ringing, or hissing tinnitus. Residual inhibition functions were measured with band-passed noise sounds varying in center frequency up to 12.0 kHz. RESULTS: The depth and duration of residual inhibition increased with the center frequency of the band-passed noise stimuli. Near-elimination of tinnitus for up to 45 s was reported by 8/24 (33%) subjects at center frequencies above 3 kHz (these cases distributed across tinnitus types). Tinnitus spectra covered the region of hearing loss with no preponderance of frequencies near the audiometric edge of normal hearing.

Adult↗
PubMed1998

A ratio code for vibrotactile pitch.

Subjective impressions of pitch for 80 different sinusoidal vibrotactile stimuli delivered to the index finger were measured by free magnitude estimation in four subjects. In three of the subjects, pitch at a given frequency decreased as stimulus amplitude increased. The data of these subjects were well described by a model of pitch based on the relative levels of activation of the three major tactile channels. The main element in this model was a ratio of P channel activity to the sum of the activity levels of the P, NPI, and NPIII channels. Activity levels of the channels were estimated on the basis of the psychophysical literature, including a study of vibrotactile loudness using the same subjects and stimuli as those employed here. A fourth subject, whose pattern of loudness judgments had previously been shown to differ from those of the other subjects, did not conform to this pitch model: her data revealed significant increases in pitch with increases in amplitude, and appear to reflect an inability to combine signals across vibrotactile channels. Pitch changes resulting from vibrotactile adaptation were directionally consistent with our ratio model: pitch was slightly increased by adaptation to a 25 Hz stimulus, and slightly decreased by 200 Hz adaptation.

Adaptation, Physiological↗
PubMed1995

Auditory P3 event related potentials (ERP) and brainstem auditory evoked responses (BAER) after spinal cord injury in humans.

Previous studies have observed altered somatotopic sensory fields after experimental deafferentation in animals as well as enhanced somatosensory evoked potentials and altered cortical motor pathways following spinal cord injury (SCI) in humans. These observations indicate that cortical reorganization may occur subsequent to SCI. In earlier work, we have observed attenuated amplitudes for both tactile P3 and auditory N1/P2 orienting event-related potentials (ERP) in spinal cord injured groups. These results suggest that the reorganization process may have functional perceptual and cognitive consequences. In an effort to determine if deafferentation affects the P3 ERP using stimuli other than somatosensory, we measured brain activity from central recording sites during an auditory "oddball" task. Additionally, we obtained brainstem auditory evoked responses (BAER) in order to assess subcortical primary auditory pathways as well. Results show that the SCI groups produced significantly attenuated N1/P2 complexes and P3 when compared to controls. Also, the quadriplegic group exhibited increased latencies of the P3 at frontal and central sites. There were no differences between groups in BAER results. These findings suggest that primary subcortical auditory information processing stages remain intact after SCI although later stages may be significantly altered.

Adult↗
PubMed2004

Switching skills on by turning off part of the brain.

Snyder and Mitchell (1999) have argued that the extraordinary skills of savants, including mathematics and drawing, are within us all but cannot normally be accessed without some form of brain damage. It has also been argued that such skills can be made accessible to normal people by switching off part of their brain artificially using magnetic pulses (Carter, 1999). Using repetitive transcranial magnetic stimulation (rTMS) to interrupt the function of the frontotemporal lobe, a region of the brain implicated in the development of savant skills (Miller et al., 1996,1998), we tested this hypothesis. Here we show that savant-type skills improved in 5 out of 17 participants during the period of stimulation. The enhanced skills included declarative memory, drawing, mathematics, and calendar calculating. In addition to overall improvement being observed, striking improvements in individual performance on various tasks were also seen.

Adult↗
PubMed2004

Measuring the tuning accuracy of thousands singing in unison: an English Premier Football League table of fans' singing tunefulness.

Tunefulness in singing is well understood in the context of solo stage performance, singing in small groups and singing in choirs, with or without accompaniment, and it can be readily measured under laboratory conditions. When thousands of people are singing outside in support of their football team, however, the singing is impromptu; there is no conductor, no starting note, and generally no accompaniment. This paper describes the measurement of the tunefulness of the singing of fans of the twenty clubs in the 2001-2002 English Premier League. The technique adopted is unusual in that it makes direct reference to the formal definition of pitch as a subjective phenomenon. The results are presented in the form of a 2001-2002 English Premier League football fans singing league table.

Acoustics↗
PubMed2006

Nonlinear modelling of double and triple period pitch breaks in vocal fold vibration.

This paper reports a study on short-time subharmonic pitch breaks in vocal fold vibration, which are found to be a common feature of the human voice in spoken language. The observed pitch breaks correspond to a change in periodicity of the electrolaryngograph (Lx) signal. This paper presents a nonlinear dynamical system capable of producing time-series with subharmonic pitch breaks. The resulting time-series resemble closely Lx recordings of natural speech. The system is developed on the basis of a second order linear system, which is extended with a third dimension and nonlinear coupling terms. It is suggested that improved knowledge about pitch breaks could be used in future speech synthesis systems in order to improve the naturalness of the perceived output.

Female↗