Biomedical subjects

S A Fausti

Publications and source records attributed to S A Fausti.

At least 19 recordsLinked to original sources

PubMed2001

Examination of the neighborhood activation theory in normal and hearing-impaired listeners.

OBJECTIVE: Experiments were conducted to examine the effects of lexical information on word recognition among normal hearing listeners and individuals with sensorineural hearing loss. The lexical factors of interest were incorporated in the Neighborhood Activation Model (NAM). Central to this model is the concept that words are recognized relationally in the context of other phonemically similar words. NAM suggests that words in the mental lexicon are organized into similarity neighborhoods and the listener is required to select the target word from competing lexical items. Two structural characteristics of similarity neighborhoods that influence word recognition have been identified; "neighborhood density" or the number of phonemically similar words (neighbors) for a particular target item and "neighborhood frequency" or the average frequency of occurrence of all the items within a neighborhood. A third lexical factor, "word frequency" or the frequency of occurrence of a target word in the language, is assumed to optimize the word recognition process by biasing the system toward choosing a high frequency over a low frequency word. DESIGN: Three experiments were performed. In the initial experiments, word recognition for consonant-vowel-consonant (CVC) monosyllables was assessed in young normal hearing listeners by systematically partitioning the items into the eight possible lexical conditions that could be created by two levels of the three lexical factors, word frequency (high and low), neighborhood density (high and low), and average neighborhood frequency (high and low). Neighborhood structure and word frequency were estimated computationally using a large, on-line lexicon-based Webster's Pocket Dictionary. From this program 400 highly familiar, monosyllables were selected and partitioned into eight orthogonal lexical groups (50 words/group). The 400 words were presented randomly to normal hearing listeners in speech-shaped noise (Experiment 1) and "in quiet" (Experiment 2) as well as to an elderly group of listeners with sensorineural hearing loss in the speech-shaped noise (Experiment 3). RESULTS: The results of three experiments verified predictions of NAM in both normal hearing and hearing-impaired listeners. In each experiment, words from low density neighborhoods were recognized more accurately than those from high density neighborhoods. The presence of high frequency neighbors (average neighborhood frequency) produced poorer recognition performance than comparable conditions with low frequency neighbors. Word frequency was found to have a highly significant effect on word recognition. Lexical conditions with high word frequencies produced higher performance scores than conditions with low frequency words. CONCLUSION: The results supported the basic tenets of NAM theory and identified both neighborhood structural properties and word frequency as significant lexical factors affecting word recognition when listening in noise and "in quiet." The results of the third experiment permit extension of NAM theory to individuals with sensorineural hearing loss. Future development of speech recognition tests should allow for the effects of higher level cognitive (lexical) factors on lower level phonemic processing.

Adult↗

PubMed2000

Efficacy of 3 commonly used hearing aid circuits: A crossover trial. NIDCD/VA Hearing Aid Clinical Trial Group.

CONTEXT: Numerous studies have demonstrated that hearing aids provide significant benefit for a wide range of sensorineural hearing loss, but no carefully controlled, multicenter clinical trials comparing hearing aid efficacy have been conducted. OBJECTIVE: To compare the benefits provided to patients with sensorineural hearing loss by 3 commonly used hearing aid circuits. DESIGN: Double-blind, 3-period, 3-treatment crossover trial conducted from May 1996 to February 1998. SETTING: Eight audiology laboratories at Department of Veterans Affairs medical centers across the United States. PATIENTS: A sample of 360 patients with bilateral sensorineural hearing loss (mean age, 67.2 years; 57% male; 78.6% white). INTERVENTION: Patients were randomly assigned to 1 of 6 sequences of linear peak clipper (PC), compression limiter (CL), and wide dynamic range compressor (WDRC) hearing aid circuits. All patients wore each of the 3 hearing aids, which were installed in identical casements, for 3 months. MAIN OUTCOME MEASURES: Results of tests of speech recognition, sound quality, and subjective hearing aid benefit, administered at baseline and after each 3-month intervention with and without a hearing aid. At the end of the experiment, patients ranked the 3 hearing aid circuits. RESULTS: Each circuit markedly improved speech recognition, with greater improvement observed for soft and conversationally loud speech (all 52-dB and 62-dB conditions, P</=.001). All 3 circuits significantly reduced the frequency of problems encountered in verbal communication. Some test results suggested that CL and WDRC circuits provided a significantly better listening experience than PC circuits in word recognition (P =.002), loudness (P =.003), overall liking (P =.001), aversiveness of environmental sounds (P =.02), and distortion (P =.02). In the rank-order ratings, patients preferred the CL hearing aid circuits more frequently (41.6%) than the WDRC (29.8%) and the PC (28.6%) (P =.001 for CL vs both WDRC and PC). CONCLUSIONS: Each circuit provided significant benefit in quiet and noisy listening situations. The CL and WDRC circuits appeared to provide superior benefits compared with the PC, although the differences between them were much less than the differences between the aided vs unaided conditions. JAMA. 2000;284:1806-1813.

Adult↗

PubMed2000

Computer-automated clinical technique for tinnitus quantification.

This study addresses the need for uniformity in techniques for clinical quantification of tinnitus. Because automation can be an effective means to achieve standardization, this laboratory is developing techniques to perform computer-automated tinnitus testing. The present study was conducted to demonstrate the feasibility of obtaining reliable tinnitus measures using a fully automated system. A computer-controlled psychoacoustical system was developed to quantify tinnitus loudness and pitch using a tone-matching technique. Hearing thresholds were also obtained as part of the procedure. The system generated test stimuli and simultaneously controlled a notebook computer positioned in the sound chamber facing the patient. The notebook computer displayed instructions for responding and relayed response choices through on-screen "buttons" that the patient touched with a pen device. Twenty individuals with tinnitus were evaluated with the technique over two sessions, and responses were analyzed for test-retest reliability. Analyses revealed good reliability of thresholds, loudness matches, and pitch matches. These results demonstrate that use of a fully automated system to obtain reliable measurements of tinnitus loudness and pitch is feasible for clinical application.

Adult↗

PubMed2000

Twenty-stimulus train for rapid acquisition of auditory brainstem responses in humans.

This study addressed the clinical need to obtain frequency-specific auditory brainstem responses (ABRs) more rapidly than is currently possible. ABRs were obtained from 20 subjects using two different methods: a conventional method with tone bursts presented singly and a multiple-stimulus method using a train of 20 tone bursts. For both methods, tone bursts were presented at frequencies 1, 2, 4, and 8 kHz, shaped with a Blackman-Harris window and having intensity levels up to 105 dB peak equivalent sound pressure level (peSPL). The single tone bursts were presented at a 17.2/sec repetition rate. The 20 tone-burst train used the four frequencies at five intensities each and a repetition rate of 3.7/sec (separations between tone bursts of 9-12 msec, with 77 msec off-time between trains). Mean latencies and mean amplitudes for wave V were compared using t-tests for each of 12 conditions (four frequencies, each at the three highest output levels). For latency, only one comparison was significantly different (2 kHz, 77 dB peSPL). Similarly, only one comparison was significant for amplitude (2 kHz, 97 dB peSPL). There was, however, a trend for the tone bursts presented in trains to have longer latencies and reduced amplitudes compared to the respective responses for the single tone-burst condition. These results indicate the presence of some response adaptation when tone bursts are presented in a train. The use of a properly designed stimulus train can result in a significant time savings for obtaining frequency-specific ABRs as compared with single tone-burst presentations.

Adult↗

PubMed1999

An individualized, sensitive frequency range for early detection of ototoxicity.

OBJECTIVE: The aim of this study was to identify auditory frequencies at which serial threshold testing would provide the greatest sensitivity for early detection of ototoxicity. The overall objective is to develop a more time-efficient ototoxicity monitoring protocol. DESIGN: Threshold data were analyzed from 370 hospitalized patients treated with aminoglycoside antibiotics (AMGs) or cisplatin (CDDP) who received serial auditory monitoring before, during, and after treatment at conventional (0.25 to 8 kHz) and high (9 to 20 kHz) frequencies. RESULTS: For patients showing hearing changes due to ototoxicity, a frequency range was identified for its apparent high sensitivity to initial ototoxicity. This sensitive range is identified according to an individual's hearing threshold configuration, and is, therefore, unique for each patient. The range consists of five frequencies, generally separated by 1/6 octave, e.g., 8, 9, 10, 11.2, and 12.5 kHz. To determine frequencies and combinations of frequencies that were most often involved in ototoxicity detection, threshold data in the sensitive range were analyzed in detail. This analysis suggests that patients receiving treatment with AMG or CDDP can be monitored for hearing thresholds at only five frequencies, resulting in an 84% detection rate for AMG and 94% for CDDP compared with monitoring at all conventional and high frequencies. CONCLUSIONS: This comprehensive analysis supports earlier observations that a sensitive, limited frequency range exists in which serial threshold monitoring will provide early warning of ototoxicity before effects in the speech frequency range. This finding is now being evaluated in a prospective investigation.

Aminoglycosides↗

PubMed1999

Reliability of tinnitus loudness matches under procedural variation.

Repeated tinnitus loudness matches (LMs) were obtained to determine response reliability using a computer-automated technique with two procedural variations, fixed or random step sizes, to increase output level during the initial ascending series of tones at each frequency. Twenty subjects with stable, tonal tinnitus were evaluated with both methods during each of two sessions. Response instructions were displayed on a portable computer, and a pen device was used to make response choices that appeared on the touch-sensitive video monitor. For each method, hearing thresholds and LMs were obtained, with 1-dB resolution, at 1/3-octave frequencies from 1 to 16 kHz. Analyses revealed reliability of LMs to be equivalent between methods. LM data are reported in both dB SPL and dB SL, with the SPL values providing greater reliability both within and between sessions (all r's > or = .889, p's < or = .0001).

Acoustic Impedance Tests↗

PubMed1998

Intrasubject reliability of high-frequency (9-14 kHz) thresholds: tested separately vs. following conventional-frequency testing.

Retrospective analysis of hearing-threshold data from a multisite ototoxicity monitoring study identified an individualized range of predominantly high frequencies (> 8 kHz) that appeared to be highly sensitive to early threshold changes caused by ototoxicity. This suggested the potential for a limited-frequency monitoring protocol that could be conducted rapidly without compromising sensitivity to ototoxicity. Such testing would require high-frequency thresholds to be obtained independently, that is, without prior testing at conventional frequencies (0.25-8 kHz). This study was conducted to determine the test-retest reliability of isolated threshold testing in a "target" frequency range of high frequencies (9, 10, 11.2, 12.5, and 14 kHz) that represented a shortened ototoxicity monitoring test. Twenty normal-hearing subjects were evaluated over five sessions. During each session, subjects were tested in each of two conditions: (1) conventional frequencies (0.25-8 kHz) tested first, followed by target frequencies; and (2) target frequencies tested alone (isolation condition). Depending on test frequency, reliability of high-frequency thresholds was either unchanged or improved in the isolation condition. Although these results cannot be generalized to ill hospitalized patients, who may also have pre-existing hearing loss, they lay the groundwork for development of a time-saving limited-frequency test to monitor for ototoxicity in these patients.

Adult↗

PubMed1995

High-frequency toneburst-evoked ABR latency-intensity functions in sensorineural hearing-impaired humans.

The latency-intensity functions (LIFs) of ABRs elicited by high-frequency (8, 10, 12, and 14 kHz) toneburst stimuli were evaluated in 20 subjects with confirmed 'moderate' high-frequency sensorineural hearing loss. Wave V results from clicks and tonebursts revealed all intra- and intersession data to be reliable (p > 0.05). Linear regression curves were highly significant (p < or = 0.0001), indicating linear relationships for all stimuli analyzed. Comparisons between the linear regression curves from a previously reported normal-hearing subject group and this sensorineural hearing-impaired group showed no significant differences. This study demonstrated that tonebursts at 8, 10, and 12 kHz evoked ABRs which decreased in latency as a function of increasing intensity and that these LIFs were consistent and orderly (14 kHz was not determinable). These results will contribute information to facilitate the establishment of change criteria used to predict change in hearing during treatment with ototoxic medications.

Acoustic Stimulation↗

PubMed1994

High-frequency audiometric monitoring strategies for early detection of ototoxicity.

Therapeutic drugs such as the aminoglycoside antibiotics (AMG) and the chemotherapy agent cisplatin (CDDP) are known to cause irreversible hearing loss, typically affecting highest frequency hearing first with progression of loss to the lower frequency regions. Conventional (0.25-8 kHz) and high-frequency (9-20 kHz) serial hearing threshold monitoring was done in 123 hospitalized patients (222 ears) administered AMG or CDDP. Of ears showing a decrease in sensitivity corresponding with treatment, 62.5% demonstrated initial hearing loss solely in the high-frequency range, 13.5% first showed loss only in the conventional-frequency range, and 24.0% showed loss in both frequency ranges concurrently. Thus, if only high frequencies had been monitored, early change in auditory sensitivity would have been detected in 86.5% of these patients. Further analysis revealed a range of five frequencies, specific to each individual's hearing threshold configuration, in which initial ototoxicity appeared most likely to be detected. Testing only these five frequencies would have identified 89.2% of ears that showed change. The results of this study confirm the need to serially monitor auditory thresholds, especially in the high-frequency range, of patients receiving ototoxic drugs. A shortened five-frequency monitoring protocol is presented and suggested for use with patients unable to tolerate lengthy audiometric testing procedures.

Aminoglycosides↗

PubMed1994

Paired tone-burst study of auditory brainstem response adaptation in guinea pigs: implications for development of multiple-stimulus methods.

In clinical testing using auditory evoked potentials, the practical length of a test session is limited. Thus, the amount of information that can be obtained during a routine test session is limited in electrocochleography and auditory brainstem testing. Attempts to obtain more information within a test session by increasing the stimulus repetition rate yields adapted responses. Multiple-stimulus method that present sequences of stimuli at different frequencies and intensities can increase the efficiency of data collection while avoiding adaptation. This study was designed to investigate rapid adaptation of these early responses to enable more efficient data acquisition using multiple stimuli. Five experiments in guinea pigs using single and paired tone-burst stimuli are described. The intrapair time, frequency, and intensity were varied to determine when adaptation, measured by a latency delay, occurred. The effects of adaptation on waves I through IV are described. The differences in stimulus parameters that avoid adaptation can be determined from these experiments.

Acoustic Stimulation↗

PubMed1994

Multiple-stimulus method for rapid collection of auditory brainstem responses using high-frequency (> or = 8 kHz) tone bursts.

Auditory brainstem responses (ABR) to high-frequency (> or = 8 kHz) tone-burst stimuli have shown potential for objective early detection of ototoxicity. In the case of ill, unresponsive, or otherwise difficult-to-test individuals, the patient group for whom this test is targeted, a threshold-seeking process can be too lengthy. A new method is described for obtaining responses to several high-frequency tone bursts in the same amount of time as that used in obtaining a single responses. Using 10 normal-hearing subjects, four high-frequency tone-burst stimuli (14, 12, 10, and 8 kHz) were presented singly, then in a multiple-stimulus sequence with onsets separated by 10 msec. Wave V response latencies from the multiple-stimulus sequences are compared to those presented singly, with small but statistically significant longer latencies observed for all stimuli following the initial stimulus (14 kHz) in the multiple sequence. Test-retest reliability was comparable between multiple and single conditions. These findings support the development of this technique for clinical auditory monitoring.

Acoustic Stimulation↗

PubMed1993

High-frequency monitoring for early detection of cisplatin ototoxicity.

Cisplatin can cause irreversible hearing loss initially detectable as impairment of high-frequency hearing with progression to lower frequencies. Many patients receiving cisplatin are too ill to tolerate lengthy audiometric testing. Therefore, a rapid and sensitive high-frequency monitoring strategy to detect cisplatin-induced ototoxicity is needed. Serial conventional (0.25 to 8 kHz) and high-frequency (> or = 8 kHz) threshold monitoring was performed in patients receiving cisplatin, resulting in 84% of ears showing hearing loss, of which 71% were detected first in frequencies of 8 kHz or greater. By analysis according to an individualized, specific high-frequency range, early identification of hearing loss occurred in 94% of ears showing change. This five-frequency procedure is a sensitive detector of ototoxicity and is proposed as an alternative monitoring protocol for patients receiving cisplatin who cannot tolerate extended testing.

Algorithms↗

PubMed1993

High-frequency tone burst-evoked ABR latency-intensity functions.

High-frequency tone burst stimuli (8, 10, 12, and 14 kHz) have been developed and demonstrated to provide reliable and valid auditory brainstem responses (ABRs) in normal-hearing subjects. In this study, latency-intensity functions (LIFs) were determined using these stimuli in 14 normal-hearing individuals. Significant shifts in response latency occurred as a function of stimulus intensity for all tone burst frequencies. For each 10 dB shift in intensity, latency shifts for waves I and V were statistically significant except for one isolated instance. LIF slopes were comparable between frequencies, ranging from 0.020 to 0.030 msec/dB. These normal LIFs for high-frequency tone burst-evoked ABRs suggest the degree of response latency change that might be expected from, for example, progressive hearing loss due to ototoxic insult, although these phenomena may not be directly related.

Acoustic Stimulation↗

PubMed1993

High-frequency testing techniques and instrumentation for early detection of ototoxicity.

Veteran patients with certain types of infections and cancers are routinely treated with therapeutic agents having ototoxic potential, thus threatening loss of hearing sensitivity which preexists in the majority of these patients. To prevent communication deficits requiring intervention, this laboratory is developing instrumentation and techniques for early detection of ototoxicity. For this study, conventional (< or = 8 kHz) and high-frequency (> or = 8 kHz) hearing thresholds were monitored behaviorally in hospitalized veterans receiving treatment with ototoxic drugs. Data analysis revealed that monitoring only the high-frequency range would have identified 67% of ears showing change. A five-frequency range of hearing, specific to each individual, was identified for its high sensitivity to early ototoxic change. Monitoring of only these five frequencies in each patient would have identified 82% of ears that showed behavioral change. Auditory brainstem responses (ABR) were obtained in a subgroup using clicks and high-frequency (8-14 kHz) tone bursts. ABR latency/morphology changes were observed in 95% of ears demonstrating behavioral change. High-frequency tone-burst-evoked ABRs alone would have identified 93% of initial changes. Monitoring of high-frequency audition using these techniques shows promise for early detection of ototoxicity with potential for prevention of hearing loss in frequencies essential for verbal communication.

Acoustic Impedance Tests↗

PubMed1992

High-frequency audiometric monitoring for early detection of aminoglycoside ototoxicity.

Treatment with aminoglycosides is known to cause irreversible hearing loss, typically affecting higher-frequency hearing first and progressing to lower frequencies. Standardized methodology has not been developed for early detection of ototoxicity. Serial conventional (0.25-8 kHz) and high-frequency (9-20 kHz) hearing threshold monitoring was done prospectively in 53 hospitalized patients administered aminoglycosides. Hearing loss occurred in 47% of the ears studied, with hearing loss first appearing in the high-frequency range in 71% of ears showing change. Analysis of data on an individual basis revealed a five-frequency range most susceptible to initial ototoxicity. Testing only this range would have resulted in early identification of 82% of ears showing change. Results confirm the critical need for serial auditory threshold monitoring encompassing high frequencies in patients receiving aminoglycosides. A shortened five-frequency monitoring protocol is presented and suggested for use with patients unable to tolerate lengthy audiometric testing procedures.

Amikacin↗

PubMed1992

Comparing laboratory and portable tone-burst auditory brain-stem-response (ABR) systems for monitoring high-frequency (> or = 8 kHz) auditory function.

High-frequency (8-20 kHz) hearing sensitivity is of special interest because of its early warning potential for ototoxicity. Many ill patients, however, are unable to respond behaviorally to auditory test procedures. To objectively monitor high-frequency auditory function in these patients, laboratory instrumentation to evoke the auditory brain-stem response (ABR) with high-frequency (8-14 kHz) tone-burst stimuli was developed and documented. To provide evaluation at bedside, a portable high-frequency tone-burst generator was developed to elicit the ABR. Combined with a portable signal averager, this system was validated by comparison with the laboratory system. Thirty-five normal-hearing subjects were used to compare ABRs to high-frequency tone bursts from each system. Analysis of responses to tone bursts revealed no significant mean latency differences, and no significant intersession reliability differences between systems. These results confirm that the portable system is comparable to the laboratory system in obtaining reliable high-frequency tone-burst responses.

Acoustic Stimulation↗

PubMed1992

Early detection of ototoxicity using high-frequency, tone-burst-evoked auditory brainstem responses.

Subjects receiving treatment with ototoxic agents were evaluated concurrently with conventional and high-frequency (> or = 8 kHz) behavioral threshold measures and with ABR to click and to 8, 10, 12, and 14 kHz tone-burst stimuli. Behavioral threshold data revealed ototoxic change in 51 percent of ears evaluated. Of these ears demonstrating behavioral change, 90 percent revealed concurrent ABR changes. If only ABR monitoring with high-frequency tone-burst stimuli had been used, 87 percent of allears showing behavioral change would have been identified. Three fourths of these would have been identified from wave V responses, with 87 percent identified from the two highest frequencies tested for each individual. This research suggests that behavioral change is reflected accurately in the ABR, that high-frequency tone bursts will identify a majority of initial ototoxic changes, and that monitoring hearing with high-frequency, tone-burst-evoked ABRs during treatment with potentially ototoxic agents is significantly more effective than click-evoked ABRs for early detection of ototoxicity.

Acoustic Impedance Tests↗

PubMed1992

Portable stimulus generator for obtaining high-frequency (8-14 kHz) auditory brainstem responses.

Currently, the most useful application of high-frequency (greater than or equal to 8 kHz) auditory evaluation is for serial monitoring of patients receiving potentially ototoxic agents. Many individuals, however, are unable to respond to behavioral auditory test techniques. An objective evaluation method such as the auditory brainstem response (ABR) is valuable with difficult-to-test individuals. Laboratory instrumentation has been demonstrated to evoke high-frequency-specific (8-14 kHz) ABRs with reliable intrasubject latencies over time. This instrumentation is limited, however, because it cannot be transported to the patient confined to a hospital room. A portable device has now been constructed to deliver high-frequency (8-14 kHz) tone-burst stimuli comparable to the lab system. This digital/analog high-frequency tone-burst stimulus generator weighs less than 5 pounds. It can be utilized with any ABR signal averager capable of generating a positive (condensing) click at approximately 4.8 volts. Case studies are presented to demonstrate the frequency-specific responses obtained with these high-frequency tone-burst stimuli.

Acoustic Stimulation↗