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Emily Buss

Publications and source records attributed to Emily Buss.

At least 19 recordsLinked to original sources
PubMed2006

Comodulation detection differences for fixed-frequency and roved-frequency maskers.

This study investigated comodulation detection differences (CDD) for fixed- and roved-frequency maskers. The objective was to determine whether CDD could be accounted for better in terms of energetic masking or in terms of perceptual fusion/segregation related to comodulation. Roved-frequency maskers were used in order to minimize the role of energetic masking, allowing possible effects related to perceptual fusion/segregation to be revealed. The signals and maskers were composed of 30-Hz-wide noise bands. The signal was either comodulated with the masker (A/A condition) or had a temporal envelope that was independent (A/B condition). The masker was either gated synchronously with the signal or had a leading temporal fringe of 200 ms. In the fixed-frequency masker conditions, listeners with low A/A thresholds showed little masking release due to masker temporal fringe and had CDDs that could be accounted for by energetic masking. Listeners with higher A/A thresholds in the fixed-frequency masker conditions showed relatively large CDDs and large masking release due to a masker temporal fringe. The CDDs of these listeners may have arisen, at least in part, from processes related to perceptual segregation. Some listeners in the roved masker conditions also had large CDDs that appeared to be related to perceptual segregation.

Acoustic Stimulation↗
PubMed2006

Temporal processing deficits in the pre-senescent auditory system.

This study tested the hypothesis that temporal processing deficits are evident in the pre-senescent (middle-aged) auditory system for listening tasks that involve brief stimuli, across-frequency-channel processing, and/or significant processing loads. A gap duration discrimination (GDD) task was employed that used either fixed-duration gap markers (experiment 1) or random-duration markers (experiment 2). Independent variables included standard gap duration (0, 35, and 250 ms), marker frequency (within- and across-frequency), and task complexity. A total of 18 young and 23 middle-aged listeners with normal hearing participated in the GDD experiments. Middle age was defined operationally as 40-55 years of age. The results indicated that middle-aged listeners performed more poorly than the young listeners in general, and that this deficit was sometimes, but not always, exacerbated by increases in task complexity. A third experiment employed a categorical perception task that measured the gap duration associated with a perceptual boundary. The results from 12 young and 12 middle-aged listeners with normal hearing indicated that the categorical boundary was associated with shorter gaps in the young listeners. The results of these experiments indicate that temporal processing deficits can be observed relatively early in the aging process, and are evident in middle age.

Adolescent↗
PubMed2006

Development and the role of internal noise in detection and discrimination thresholds with narrow band stimuli.

The experiments reported here examine the role of internal noise in the detection of a tone in narrow band noise and intensity discrimination for narrow band stimuli in school-aged children as compared to adults. Experiment 1 used 20-Hz wide bands of Gaussian and low-fluctuation noise centered at 500 Hz to assess the role of stimulus fluctuation in detection of a 500-Hz pure tone. Additional conditions tested whether performance was based on level and/or level-independent cues. Children's thresholds were elevated with respect to adults, and whereas adults benefited from the reduced fluctuation of low-fluctuation noise, children did not. Results from both groups were consistent with the use of a level cue. Experiment 2 estimated intensity increment thresholds for a narrow band Gaussian noise or a pure tone, either with or without a presentation-by-presentation level rove, an additional source of level variability. Stimulus variability was found to have a larger effect on performance of adults as compared to children, a rather counterintuitive finding if one thinks of children as more prone to informational masking introduced by stimulus variability. Both tone-in-noise and intensity discrimination data were consistent with the hypothesis that children's performance is limited by greater levels of internal noise.

Acoustic Stimulation↗
PubMed2006

Binaural comodulation masking release: effects of masker interaural correlation.

Binaural detection was examined for a signal presented in a narrow band of noise centered on the on-signal masking band (OSB) or in the presence of flanking noise bands that were random or comodulated with respect to the OSB. The noise had an interaural correlation of 1.0 (No), 0.99 or 0.95. In No noise, random flanking bands worsened Spi detection and comodulated bands improved Spi detection for some listeners but had no effect for other listeners. For the 0.99 or 0.95 interaural correlation conditions, random flanking bands were less detrimental to Spi detection and comodulated flanking bands improved Spi detection for all listeners. Analyses based on signal detection theory indicated that the improvement in Spi thresholds obtained with comodulated bands was not compatible with an optimal combination of monaural and binaural cues or to across-frequency analyses of dynamic interaural phase differences. Two accounts consistent with the improvement in Spi thresholds in comodulated noise were (1) envelope information carried by the flanking bands improves the weighting of binaural cues associated with the signal; (2) the auditory system is sensitive to across-frequency differences in ongoing interaural correlation.

Adult↗
PubMed2005

MED-EL Combi40+ cochlear implantation in adults.

OBJECTIVE/HYPOTHESIS: Cochlear implantation is currently the treatment of choice for severe to profound sensorineural hearing loss. The MED-EL Combi40+ (Innsbruck, Austria) cochlear implant system was approved for use in the United States in 2001. This device employs a 31-mm-long electrode array, ceramic case, and continuous interleaved sampling with Hilbert transformation for envelope extraction. A single institution's experience with the Combi40+ implant in adult patients was reviewed. STUDY DESIGN: Retrospective chart review. METHODS: Medical-surgical and audiological data were collected from 112 patients who received a MED-EL Combi40+ cochlear implant between December 1998 and April 2004. RESULTS: The rate of surgical complications and speech perception testing results compared favorably with those of other cochlear implant systems. For postlingually deafened adults, mean CNC word, HINTQ, CUNY, and HINT + 10 dB signal-to-noise ratio scores after 1 year of implant usage were 54%, 87%, 96%, and 64%, respectively. Prelingually deafened adults also derived significant benefit, but plateau performance for these patients was well below that for patients with later onset of deafness and significant variability was seen in this group. Repeat implantation for suspected device malfunction was undertaken in seven cases (6% of devices) (mean duration of use, 28 +/- 12 mo) with ultimate resolution of the presenting problem. CONCLUSION: The study results support the safety and efficacy of cochlear implantation with the MED-EL Combi40+ cochlear implant system.

Adolescent↗
PubMed2005

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.

Acoustic Stimulation↗
PubMed2005

Detection of spectrally complex signals in comodulated maskers: effect of temporal fringe.

This study tested the hypothesis that masking release for a complex signal under conditions where signal energy is present in all frequency regions occupied by the masker is attributable to an across-frequency-channel comodulation masking release (CMR) process. The approach was to identify a signature CMR trait, and to then determine if that trait was associated with the detection advantage for complex signals. The selected trait was the decline of CMR in the presence of a random temporal fringe. In experiment 1, a masking release was observed for a four-component harmonic signal presented in a comodulated masker, and this masking release was diminished by the random temporal fringe. A similar effect was observed in experiment 2 for a four-component inharmonic signal. These results support the hypothesis that a CMR can be measured for a complex signal even when there is substantial spectral overlap between the signal and its comodulated masker. This finding has consequences for CMR models since it demonstrates that the presence of "signal-free" cue bands is not a prerequisite for CMR, and that the presence of comodulation during the signal window is not sufficient to result in CMR.

Acoustic Stimulation↗
PubMed2004

Duration discrimination in listeners with cochlear hearing loss: effects of stimulus type and frequency.

This study examined the effects of cochlear hearing loss on the ability to discriminate increments in the duration of a stimulus under conditions where the frequency and/or amplitude of the stimulus change dynamically. Three stimulus types were used: pure tones, frequency-modulated tones, and narrow bands of noise. The carrier/center frequency of each 250-ms stimulus either remained constant at 1035 Hz or varied randomly from presentation to presentation across the frequency range 432-2804 Hz. Two groups of listeners participated: 9 with bilateral cochlear hearing loss and 7 with normal hearing sensitivity. The results showed no differences in performance between the 2 groups. However, both groups showed poorer duration discrimination for the conditions where the carrier/center frequency changed randomly than for the conditions where the carrier/center frequency remained constant. In addition, performance was poorer for the narrowband noise stimuli than for the tonal stimuli. This pattern of results suggests that across-frequency temporal judgments are more difficult than isofrequency temporal judgments, but that cochlear hearing loss does not exacerbate this difficulty per se.

Acoustic Stimulation↗
PubMed2004

Developmental effects in the masking-level difference.

Adults and children (aged 5 years 1 month to 10 years 8 months) were tested in a masking-level difference (MLD) paradigm in which detection of brief signals was contrasted for signal placement in masker envelope maxima versus masker envelope minima. Maskers were 50-Hz-wide noise bands centered on 500 Hz, and the signals were So or Sp 30-ms, 500-Hz tones. In agreement with previous studies, it was found that MLDs were greater for masker envelope minima placement than for masker envelope maxima placement. Across the age range of the children tested here, the binaural advantage associated with the masker envelope minima increased with the age of the child. One interpretation of the present results is that there is a developmental improvement in binaural temporal resolution over the age range tested here.

Acoustic Stimulation↗
PubMed2004

Temporal fine-structure cues to speech and pure tone modulation in observers with sensorineural hearing loss.

OBJECTIVE: The purpose of this study was to examine the effect of sensorineural hearing loss on the ability to make use of fine temporal information and to evaluate the relation between this ability and the ability to recognize speech. DESIGN: Fourteen observers with normal hearing and 12 observers with sensorineural hearing loss were tested on open-set word recognition and on psychophysical tasks thought to reflect use of fine-structure cues: the detection of 2 Hz frequency modulation (FM) and the discrimination of the rate of amplitude modulation (AM) and quasifrequency modulation (QFM). RESULTS: The results showed relatively poor performance for observers with sensorineural hearing loss on both the speech recognition and psychoacoustical tasks. Of particular interest was the finding of significant correlations within the hearing-loss group between speech recognition performance and the psychoacoustical tasks based on frequency modulation, which are thought to reflect the quality of the coding of temporal fine structure. CONCLUSIONS: These results suggest that sensorineural hearing loss may be associated with a reduced ability to use fine temporal information that is coded by neural phase-locking to stimulus fine-structure and that this may contribute to poor speech recognition performance and to poor performance on psychoacoustical tasks that depend on temporal fine structure.

Adult↗
PubMed2004

Cochlear implantation in patients with substantial residual hearing.

OBJECTIVES: Cochlear implantation is an effective means for providing auditory rehabilitation in adult patients with severe to profound sensorineural hearing loss. It has been hypothesized that patients with substantial, preoperative residual hearing would be excellent cochlear implant candidates because of surviving neural populations and a lack of auditory deprivation. The purpose of this study is to describe the outcomes of patients with substantial residual hearing who have undergone cochlear implantation. STUDY DESIGN: Retrospective chart review of patients with substantial preoperative residual hearing who underwent cochlear implantation. METHODS: Chart reviews were completed for patients with substantial residual hearing who underwent cochlear implantation (City University of New York Sentence Test [CUNY] > 60%, Hearing in Noise Test sentences presented in quiet [HINTQ] > 50%, or Consonant-Nucleus-Consonant [CNC] > 20% in the ear to be implanted). Preoperative and postoperative measures of audiologic performance as well as complications were assessed. RESULTS: All 12 patients who met inclusion criteria ultimately surpassed their preoperative aided performance level after implantation and gained significant benefit from their cochlear implant. At 6 months postimplantation, mean CUNY, HINTQ, and CNC scores were 93%, 78%, and 48% in the implant ear alone, respectively. However, progress was slower than expected for many patients, and at least one patient took 1 year to surpass his preoperative performance level. There were no complications from surgery in this selected group of patients. CONCLUSIONS: Patients with some degree of residual hearing do benefit from cochlear implantation. However, there may be an initial decline in performance as compared with preoperative levels. This decline is overcome in time in this patient population. These patients need to be counseled accordingly.

Age Factors↗
PubMed2004

Spectral integration of synchronous and asynchronous cues to consonant identification.

The goal of the present research was to determine how well observers utilize cues to consonant identification from different spectral regions that occur asynchronously as opposed to synchronously across frequency; such an ability would be useful for processing speech in the context of a spectro-temporally complex masker (e.g., competing speech). This was assessed by obtaining masked identification thresholds for VCV speech material, of the form /a/ C /a/, under various conditions of 10-Hz or 20-Hz square-wave amplitude modulation (AM). The speech tokens were filtered into 2, 4, 8, or 16 contiguous log-spaced frequency bands spanning 0.1 to 10 kHz. Bands were then modulated, with the pattern of that AM being either coherent across bands or 180 degrees out of phase for adjacent bands. In the out-of-phase conditions the odd-numbered bands had coherent phase AM and the even bands had coherent phase AM, but the AM pattern across these two subsets of bands were out of phase. Results from these two conditions, along with further conditions employing only modulated even- or odd-numbered bands, allowed performance to be compared between stimuli characterized by synchronous and asynchronous cues. Results indicate that observers are able to utilize asynchronously presented cues to consonant identification efficiently across a range of conditions.

Acoustic Stimulation↗
PubMed2003

The effect of otitis media with effusion on perceptual masking.

OBJECTIVE: To determine the effect of otitis media with effusion (OME) on perceptual masking (a phenomenon in which spondee threshold for a 2-talker masker is poorer than for a speech-shaped noise masker). DESIGN: Longitudinal testing over a 1-year period following insertion of tympanostomy tubes, using clinical and normal-hearing control groups. SUBJECTS: Forty-seven children having a history of OME were tested. Possible testing intervals were just before the placement of tympanostomy tubes, and up to 3 separate occasions after the placement of the tubes. An age-matched control group of 19 children was tested. METHODS: A perceptual masking paradigm was used to measure the ability of the listener to recognize a spondee in either a speech-shaped noise or a 2-talker masker background. The masker was either continuous or gated on and off with the target spondee. RESULTS: In gated masking conditions, children with a history of normal hearing showed only slight perceptual masking, but the children with a history of OME showed relatively great perceptual masking before surgery and up to 6 months following surgery. In continuous masking conditions, both groups of children showed relatively great perceptual masking and did not differ significantly from each other in this respect either before or after surgery. However, before surgery, the OME group showed higher thresholds in both the 2-talker and speech-shaped noise maskers. CONCLUSIONS: In agreement with previous psychoacoustical findings, the relatively great perceptual masking in gated conditions shown by children with OME history may reflect a general deficit in complex auditory processing.

Age Factors↗
PubMed2003

Rapid adaptation of the 2f1-f2 DPOAE in humans: binaural and contralateral stimulation effects.

The present data were collected in humans to characterize the effects of monaural and binaural stimulation and contralateral noise on the 2f1-f2 distortion-product otoacoustic emission (DPOAE) adaptation response. DPOAE levels (f2/f1=1.21, L1=70 dB SPL, L2=65 dB SPL) were measured in both ears for a range of f2 frequencies (1.2 to 10.0 kHz). The f2 frequency producing the largest amplitude DPOAE was used for further testing employing three different stimulus conditions: the primary tones were presented to only one ear for 4 s; the two tones were presented simultaneously in both ears; and, contralateral broadband noise (60 dB SPL) was presented for 5 s, beginning 4 s after the onset of the monaural primaries in the test ear. Acoustic reflex thresholds were measured to verify that the middle-ear muscles played no systematic role in the measured DPOAE reductions. Estimates of monaural rapid adaptation levels and time constants agreed well with previous human findings. The magnitude of the rapid adaptation under binaural stimulation, as compared with monaural primaries, was 25% greater on average, though adaptation time constants were comparable. With added contralateral noise, the average DPOAE suppression was 1.1 dB (0.3-2.7 dB). The magnitude of the monaural adaptation and the effects of binaural and contralateral stimulation, however, were smaller than those measured previously in experimental animals, though the time constants were in good agreement.

Acoustic Stimulation↗
PubMed2003

Effect of amplitude modulation coherence for masked speech signals filtered into narrow bands.

Introduction of masker amplitude modulation (AM) can improve signal detection in a number of paradigms. In some cases this advantage depends on the coherence of modulation across a relatively wide frequency range. In the experiments described below, observers were asked to identify masked spondee words produced by a single male talker. The target spondees and masking noise were filtered into nine narrow bands, and the coherence of AM of either the speech signal or noise masker was manipulated. Inherent modulation of the masker bands was manipulated via assignment of real and imaginary values to the associated components of each band in the frequency domain, and AM of speech bands was achieved via multiplication with envelopes extracted from these maskers. Responses were based on two alternatives, four alternatives, or open response sets. The effect of masker AM coherence was highly dependent upon the size of the response set: coherent AM was associated with better thresholds in a two-alternative response set, but poorer thresholds in an open response set. Results with AM speech did not depend critically upon the across-frequency temporal synchrony of AM imposed on the speech material.

Adult↗
PubMed2003

Modulation rate discrimination for unresolved components: temporal cues related to fine structure and envelope.

The present study investigated the hypothesis that the cues for modulation rate discrimination for unresolved spectral components differ as a function of the spectral region occupied by the stimuli. Specifically, it was hypothesized that when components occupy relatively low spectral regions, phase locking both to the fine structure and to the envelope are useful cues. However, as the spectral region occupied by the components increases, phase locking to the fine structure becomes less robust, whereas phase locking to the envelope remains as a potentially strong cue. Observers were asked to detect a decrease in modulation rate for carrier frequencies between 1500 and 6000 Hz. Both amplitude-modulated (AM) and quasifrequency-modulated (QFM) tones were used in order to produce stimuli having strong and weak envelope cues, respectively. Although there were marked individual differences, the results showed an interaction between modulation type and spectral region, with AM and QFM performance being relatively similar at low spectral region, but with QFM showing a steeper reduction in performance as the spectral region of the carrier frequency increased. Overall, the data are consistent with an interpretation that pitch perception for unresolved components depends upon both fine structure and envelope cues, and that the relative importance of these cues depends upon the spectral region occupied by the stimuli.

Adult↗
PubMed2003

The masking level difference for signals placed in masker envelope minima and maxima.

Previous data on the masking level difference (MLD) have suggested that NoSpi detection for a long-duration signal is dominated by signal energy occurring in masker envelope minima. This finding was expanded upon using a brief 500-Hz tonal signal that coincided with either the envelope maximum or minimum of a narrow-band Gaussian noise masker centered at 500 Hz, and data were collected at a range of masker levels. Experiment 1 employed a typical MLD stimulus, consisting of a 30-ms signal and a 50-Hz-wide masker with abrupt spectral edges, and experiment 2 used stimuli generated to eliminate possible spectral cues. Results were quite similar for the two types of stimuli. At the highest masker level the MLD for signals coinciding with masker envelope minima was substantially larger than that for signals coinciding with envelope maxima, a result that was primarily due to decreased NoSpi thresholds in masker minima. For most observers this effect was greatly reduced or eliminated at the lowest masker level. These level effects are broadly consistent with the presence of physiological background noise and with a level-dependent binaural temporal window. Comparison of these results with predictions of a published model suggest that basilar-membrane compression alone does not account for this level effect.

Acoustic Stimulation↗