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Biomedical subjects

E M Burns

Publications and source records attributed to E M Burns.

At least 19 recordsLinked to original sources
PubMed1999

A comparison of monotic and dichotic complex-tone pitch perception in listeners with hearing loss.

The perception of fundamental pitch for two-harmonic complex tones was examined in musically experienced listeners with cochlear-based high-frequency hearing loss. Performance in a musical interval identification task was measured as a function of the average rank of the lowest harmonic for both monotic and dichotic presentation of the harmonics at 14 dB Sensation Level. Listeners with hearing loss demonstrated excellent musical interval identification at low fundamental frequencies and low harmonic numbers, but abnormally poor identification at higher fundamental frequencies and higher average ranks. The upper frequency limit of performance in the listeners with hearing loss was similar in both monotic and dichotic conditions. These results suggest that something other than frequency resolution per se limits complex-tone pitch perception in listeners with hearing loss.

Aged↗
PubMed1999

The influence of musical training on the perception of sequentially presented mistuned harmonics.

The question of whether musical scales have developed from a processing advantage for frequency ratios based on small integers, i.e., ratios derived from relationships among harmonically related tones, is widely debated in musicology and music perception. In the extreme position, this processing advantage for these so-called "natural intervals" is assumed to be inherent, and to apply to sequentially presented tones. If this is the case, evidence for this processing advantage should show up in psychoacoustic experiments using listeners from the general population. This paper reports on replications and extensions of two studies from the literature. One [Lee and Green, J. Acoust. Soc. Am. 96, 716-725 (1994)] suggests that listeners from the general population can in fact determine whether sequentially presented tones are harmonically related. The other study [Houtgast, J. Acoust. Soc. Am. 60, 405-409 (1976)] is interpreted in different terms, but could be confounded by such an ability. The results of the replications and extensions, using listeners of known relative pitch proficiency, are consistent with the idea that only trained musicians can reliably determine whether sequentially presented tones are harmonically related.

Auditory Perception↗
PubMed1999

Quantitative measurement of mammalian chromosome mitotic loss rates using the green fluorescent protein.

We have measured the mitotic loss rates of mammalian chromosomes in cultured cells. The green fluorescent protein (GFP) gene was incorporated into a non-essential chromosome so that cells containing the chromosome fluoresced green, while those lacking it did not. The proportions of fluorescent and non-fluorescent cells were measured by fluorescence activated cell sorter (FACS) analysis. Loss rates ranged from 0.005% to 0.20% per cell division in mouse LA-9 cells, and from 0.02% to 0.40% in human HeLa cells. The rate of loss was elevated by treatment with aneugens, demonstrating that the system rapidly identifies agents which induce chromosome loss in mammalian cells.

Aneuploidy↗
PubMed1998

Energy reflectance in the ear canal can exceed unity near spontaneous otoacoustic emission frequencies.

There is some controversy in the literature over whether the so-called "active mechanism" or "cochlear amplifier" is actually a power amplifier that can produce an output signal with more power than its input, or whether it simply minimizes dissipative losses within the cochlea without providing an actual power gain greater than unity. A corollary of this controversy is whether spontaneous otoacoustic emissions (SOAEs) represent the output of a nonlinear oscillator mechanism, i.e., a power amplifier which can produce an oscillatory output signal in the absence of an input oscillatory signal, or whether they represent the output of a noise-driven, passive, nonlinear system. This paper describes measurements of energy reflectance, and acoustic impedance in the ear canals of human subjects with strong SOAEs. The reflectance, and the resistive and reactive parts of the acoustic impedance, all show a frequency fine structure which correlates with SOAE frequencies, and which becomes more pronounced at low stimulus levels. In some ears at some SOAE frequencies, energy reflectance exceeds unity, and correspondingly, acoustic resistance is negative. This result demonstrates that there is a power gain at these frequencies: The power reflected from the cochlea to the ear canal exceeds the power incident. It is also consistent with the theory that these SOAEs are produced by a nonlinear oscillator mechanism in the cochlea.

Ear Canal↗
PubMed1995

Evoked potentials in subjects at risk for Alzheimer's disease.

Evoked potential (EP) changes accompanying dementing processes have been documented in a number of studies. However, EPs have not been studied in subjects who are at heightened risk for the development of Alzheimer's Disease (AD). Nineteen volunteers with no immediate family members with a history of AD and 33 healthy subjects with at least one first-degree relative with AD were studied. Of the 33 subjects with a positive family history of AD, the illness of the sick relative was classified as possible AD in 10 subjects, probable AD in 17 subjects, and definite (autopsy-proven) AD in 6 subjects. Mid-latency evoked potentials (P50, N100, and P200) and P300 event-related potentials were recorded in an oddball paradigm. The amplitudes of the P50 responses to the frequent stimuli and of the P300 responses were significantly higher in the subjects whose relatives had definite AD as compared with the other three groups. The amplitude of the N100 component was also larger in the same group, but the difference was only statistically significant from the group of healthy volunteers without a family history of AD. A process of increased sensitivity to incoming stimuli may be reflected in the increased P50, N100, and P300 amplitudes in the subjects at increased risk for developing AD.

Alzheimer Disease↗
PubMed1995

Reliability of observer ratings in the assessment of personality disorders: a preliminary study.

A 200-item, self-report personality disorder inventory (Coolidge Axis II Inventory; CATI) was administered to 52 married target subjects. Their spouses and a close friend completed a significant-other form about the targets. The mean correlation across all personality disorder scales was .51 for the targets-spouses, .36 for the targets-friends, and .41 for the spouses-friends. Twenty-eight target-spouse correlations were significant and ranged from .99 to -.40. The mean correlation for the individual 13 personality disorder scales was .46 for target-spouses and ranged from .63 for the histrionic scale to .27 for the paranoid scale. The results were interpreted as establishing a basis for significant other assessment of personality disorders.

Adult↗
PubMed1994

Longitudinal measurements of spontaneous otoacoustic emissions in infants.

It has previously been shown [E. M. Burns, K. H. Arehart, and S. L. Campbell, J. Acoust. Soc. Am. 91, 1575-1581 (1992)] that both the overall prevalence of spontaneous otoacoustic emissions (SOAEs) and most of the various gender- and ear-related prevalence tendencies are not significantly different in 1-month-olds and adults. However, large differences were found between the neonates and adults in the distributions of the frequencies and levels of SOAEs. Both the average level and the median frequency were significantly higher in infants. To obtain longitudinal SOAE data, infants from this original group of 1-month-olds were tested at ages 3, 6, 12, and 24 months. In general, individual SOAEs decrease in level with age, and high-frequency SOAEs tend to show the largest decreases. No substantial shifts occur in the frequencies of individual SOAEs. The frequency and level distributions at 24 months of age are still not adult-like. SOAEs which show short-term instabilities in frequency and/or amplitude at 1 month of age typically continue to evidence such instabilities at later ages. These results suggest the cochlea is adult-like at birth, and imply that the observed SOAE changes reflect developmental changes in the external and middle ear.

Age Factors↗
PubMed1994

Pressure transfer function and absorption cross section from the diffuse field to the human infant ear canal.

The diffuse-field pressure transfer function from a reverberant field to the ear canal of human infants, ages 1, 3, 6, 12, and 24 months, has been measured from 125-10700 Hz. The source was a loudspeaker using pink noise, and the diffuse-field pressure and the ear-canal pressure were simultaneously measured using a spatial averaging technique in a reverberant room. The results in most subjects show a two-peak structure in the 2-6-kHz range, corresponding to the ear-canal and concha resonances. The ear-canal resonance frequency decreases from 4.4 kHz at age 1 month to 2.9 kHz at age 24 months. The concha resonance frequency decreases from 5.5 kHz at age 1 month to 4.5 kHz at age 24 months. Below 2 kHz, the diffuse-field transfer function shows effects due to the torsos of the infant and parent, and varies with how the infant is held. Comparisons are reported of the diffuse-field absorption cross section for infants relative to adults. This quantity is a measure of power absorbed by the middle ear from a diffuse sound field, and large differences are observed in infants relative to adults. The radiation efficiencies of the infant and the adult ear are small at low frequencies, near unity at midfrequencies, and decrease at higher frequencies. The process of ear-canal development is not yet complete at age 24 months. The results have implications for experiments on hearing in infants.

Age Factors↗
PubMed1994

Frequency and frequency-ratio resolution by possessors of absolute and relative pitch: examples of categorical perception.

The methodology derived from the trace-context theory of intensity resolution (Durlach and Braida, 1969; Macmillan et al., 1988) was applied to resolution over an octave range along two continua: a sequential-frequency-ratio continuum for possessors of relative pitch (RP), and a pure-tone frequency continuum for possessors of absolute pitch (AP). The performance of both RP and AP possessors was exceptional in that total identification sensitivity along both continua was much greater than identification sensitivity along unidimensional psychophysical continua characterized by the 7 +/- 2 rule. In addition, the performance of RP possessors was exceptional in that, on average, total sensitivity for identification resolution was greater than sensitivity for resolution in discrimination. Finally, identification sensitivity between category prototypes (chromatic semits) along both continua was approximately the same as identification sensitivity between phonemic category prototypes along speech continua, despite the fact that both the discrimination ranges and the total number of categories are much larger for the two pitch continua.

Humans↗
PubMed1993

Voluntary contraction of middle ear muscles: effects on input impedance, energy reflectance and spontaneous otoacoustic emissions.

Two types of measurements were performed on a subject able to voluntarily contract her middle ear muscles (MEM). First, wideband measurements (0-11 kHz) of middle ear input impedance and energy reflectance were obtained when the subject was relaxed and when she contracted her MEM. The changes in impedance observed with voluntary MEM contraction were similar to those reported in the literature for acoustically-elicited MEM contractions. The energy reflectance increased for frequencies below about 4 kHz. Second, the effects of voluntary MEM contraction on the frequencies and levels of spontaneous otoacoustic emissions (SOAEs) were measured and compared to effects evoked by contralateral acoustic stimulation. Effects on SOAEs appear to be a more sensitive indicator of MEM activity than changes in impedance, and the effects due to voluntary MEM contraction were qualitatively similar to those evoked by contralateral acoustic stimulation. These results suggest that in subjects with normally-functioning middle ears, only some effects on otoacoustic emissions caused by contralateral stimuli whose levels are below the contralateral acoustic reflex threshold can be unequivocally attributed to the action of cochlear efferents. The temporal aspects of SOAE frequency shifts caused by voluntary contraction of MEM show that voluntary contraction fatigues rapidly over a time period of tens of seconds.

Acoustic Impedance Tests↗
PubMed1993

Ear-canal impedance and reflection coefficient in human infants and adults.

The ear-canal impedance and reflection coefficient were measured in an adult group and in groups of infants of age 1, 3, 6, 12, and 24 months over frequency range 125-10,700 Hz. The development of the external ear canal and middle ear strongly affect input impedance and reflection coefficient responses, and this development is not yet complete at age 24 months. Contributing factors include growth of the area and length of the ear canal, a resonance in the ear-canal walls of younger infants, and a probable influence of growth of the middle-ear cavities. The middle-ear compliance is lower in infants than adults, and the middle-ear resistance is higher. The power transfer into the middle ear of the infant is much less than into that of the adult. Such differences in power transfer directly influence both behavioral and physiological measurements of hearing. The difficulties of interpretation of neonatal tympanograms are shown to be a consequence of ear-canal wall vibration. Impedance and reflectance measurements in the 2-4-kHz range are recommended as a potentially useful clinical tool for circumventing these difficulties.

Acoustic Impedance Tests↗
PubMed1993

Effects of contralateral acoustic stimulation on spontaneous otoacoustic emissions.

Spontaneous otoacoustic emissions (SOAEs) were measured in the ear canal of adult humans prior to, during, and following presentation of tonal and broadband stimuli to the contralateral ear. Tones were presented at a fixed level at ten frequencies relative to the SOAE. Broadband noise was presented at eight levels, from 6 to 76 dB SPL. Shifts in SOAE frequency and amplitude were observed for some subjects, for some tone conditions. Frequency shifts were always positive, whereas amplitude shifts were variable. No apparent pattern of tuning was seen, such that tones with a particular frequency relationship to the SOAEs induced greater changes in the SOAEs. Systematic changes in frequency and amplitude of SOAEs were observed for increasing level of broadband noise for all subjects. Results are discussed with respect to possible mechanism(s) responsible for the alterations in SOAEs: Transcranial conduction; the olivocochlear system; and/or the middle-ear reflex arc.

Acoustic Stimulation↗
PubMed1992

Prevalence of spontaneous otoacoustic emissions in neonates.

The prevalence of spontaneous otoacoustic emissions (SOAEs) was measured in a group of 100 neonates and in a group of 50 normal-hearing young adults. The prevalence of SOAEs in the adult group (0.62) is at the high end of the range of prevalences reported in other surveys of adult SOAEs based on measurements using similar microphones. The prevalence of SOAEs in neonates (0.64) is not significantly different from that in adults. The various tendencies that have been found to be significant in the pooled results of other surveys are also evident in our adult group: more SOAEs in right ears, a higher prevalence of SOAEs in females, and a dependence between ears for the occurrence of SOAEs. The above-mentioned tendencies are also significant in the infant data. The major differences between the infant and adult results are the predominant SOAE frequency range and the average levels of SOAEs. The majority of adult SOAEs are between 1.0 and 2.0 kHz, whereas the majority of neonatal SOAEs are between 2.5 and 5.0 kHz. The average SOAE level is -2.6 dB SPL for adults and 8.5 dB SPL for infants.

Adult↗
PubMed1990

A comparison of psychometric functions for detection in normal-hearing and hearing-impaired listeners.

Psychometric functions (PFD) for the detection of pure tones were obtained with a two-interval forced-choice procedure from a group of listeners with normal hearing and a group of listeners with sensorineural impairments of presumed cochlear origin. Five PFDs were obtained for each group at each of the four test frequencies (500, 2000, 4000, and 8000 Hz). The slopes of PFDs were abnormally steep in some of the hearing-impaired listeners, but were statistically significant only at 2000 Hz.

Adolescent↗
PubMed1988

Suppression tuning curves for spontaneous otoacoustic emissions in infants and adults.

Suppression tuning curves (STCs) for spontaneous otoacoustic emissions (SOAEs) were longitudinally obtained in seven infants (at 3 weeks, 2 months, and 3, 4, or 6 months of age) and in five adults. Excellent reproducibility was obtained for adult STCs. Reproducibility for infant STCs was poorer, but the curves at each age resemble those of adults both qualitatively and quantitatively as measured by slopes of the lower and upper segments of the STCs and by Q10's. Evidence from two subjects suggests that developmental changes in the fine tuning of the system may occur postnatally. Results are discussed with respect to the development of cochlear frequency selectivity.

Acoustic Stimulation↗
PubMed1988

Pathophysiology and etiology of Alzheimer's disease.

Morphologic, neurochemical, and physiologic alterations in the brain constitute the biologic correlates of aging and of progressive, irreversible deterioration in mental function and personality characteristics of Alzheimer's disease.

Aged↗
PubMed1987

Rapid dynamic CT scanning to distinguish schizophrenic from normal subjects.

Rapid dynamic computerized axial tomography (CT) density-time curves were used to detect abnormal brain regions in groups of controls and DSM-III diagnosed schizophrenics. Density-time curves were designated as plateau curves if, following a bolus injection of contrast material, they exhibited a plateau from the peak value rather than a decrease. Five of the 10 schizophrenics versus none of the 11 controls were found to possess two or more plateau curves. The physiological basis for the plateau curves is not known, but an increase in blood-brain-barrier permeability could be involved.

Adult↗