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Biomedical subjects

L S Eisenberg

Publications and source records attributed to L S Eisenberg.

At least 19 recordsLinked to original sources
PubMed2000

Speech recognition with reduced spectral cues as a function of age.

Adult listeners are able to recognize speech even under conditions of severe spectral degradation. To assess the developmental time course of this robust pattern recognition, speech recognition was measured in two groups of children (5-7 and 10-12 years of age) as a function of the degree of spectral resolution. Results were compared to recognition performance of adults listening to the same materials and conditions. The spectral detail was systematically manipulated using a noise-band vocoder in which filtered noise bands were modulated by the amplitude envelope from the same spectral bands in speech. Performance scores between adults and older children did not differ statistically, whereas scores by younger children were significantly lower; they required more spectral resolution to perform at the same level as adults and older children. Part of the deficit in younger children was due to their inability to utilize fully the sensory information, and part was due to their incomplete linguistic/cognitive development. The fact that young children cannot recognize spectrally degraded speech as well as adults suggests that a long learning period is required for robust acoustic pattern recognition. These findings have implications for the application of auditory sensory devices for young children with early-onset hearing loss.

Adult↗
PubMed1998

Subjective judgements of clarity and intelligibility for filtered stimuli with equivalent speech intelligibility index predictions.

The purpose of this investigation was to determine whether subjective judgments of clarity or intelligibility would be rated equally among conditions in which speech was equated for predicted intelligibility (using the Speech Intelligibility Index, SII) but varied in bandwidth. Twenty listeners with normal hearing rated clarity and intelligibility for sentence material (Hearing In Noise Test) in speech-shaped noise at six paired low- and high-pass filtered conditions in which SII was equated for each pair. For three paired conditions, predicted intelligibility increased as SII increased monotonically (0.3, 0.4, 0.5). In the remaining paired conditions, SII continued to increase monotonically (0.6, 0.7, 0.8) but predicted intelligibility was held at a maximal level (> or = 95%). Predicted intelligibility was estimated from the transfer function relating SII to speech recognition scores determined in preliminary experiments. Differences in ratings between paired low- and high-pass filtered sentences did not reach statistical significance for either clarity or intelligibility, indicating that the spectral differences at equivalent SIIs did not influence the judgments for either of the two dimensions. For conditions in which predicted intelligibility increased, both clarity and intelligibility ratings increased in a similar manner. For conditions in which predicted intelligibility was maximized, intelligibility ratings remained the same statistically across conditions while clarity ratings changed modestly. Although high correlations were observed between clarity and intelligibility ratings, intelligibility ratings were consistently higher than clarity ratings for comparable conditions. The results indicated that listeners with normal hearing produced clarity and intelligibility ratings for the same speech material and experimental conditions that were highly related but differed in magnitude. Caution is required when substituting clarity for intelligibility.

Adolescent↗
PubMed1997

Subjective judgments of speech clarity measured by paired comparisons and category rating.

OBJECTIVE: The purpose of this study was to compare listeners' subjective judgments of speech clarity via paired comparisons and category rating using stimulus conditions that varied in the relative spacing between stimulus items, producing either a wide or narrow range of performance. DESIGN: Subjective judgments of speech clarity were measured via paired comparisons and category rating in 12 normal-hearing (Experiment 1) and eight hearing-impaired adults (Experiment 2). Sentences processed by six band-pass filters that increased monotonically in Articulation Index (AI) estimates constituted the stimuli to be judged. Using subsets of three filters from the group of six, subjective judgments were additionally obtained for stimulus conditions in which the performance ranges were wide (large differences in AI) and narrow (small differences in AI). RESULTS: Speech clarity judgments obtained by paired comparisons and category rating were highly related to the AI estimates both for normal-hearing and hearing-impaired subjects. When the performance range was wide, both methods provided similar judgments for the normal-hearing subjects. For the hearing-impaired subjects, paired comparisons were more sensitive than category rating. When the performance range was narrow, paired comparisons were more sensitive than category rating in differentiating between filters for both groups of subjects. This difference was less obvious for the normal-hearing subjects when paired comparison data were converted to a scale comparable to the category ratings. Large between-subject variability was evident for the hearing-impaired subjects on the psychophysical scaling procedures, most notably for category rating. CONCLUSIONS: When judging the clarity among stimulus items where performance varied over a wide range, both category rating and paired comparisons provided comparable judgments for normal-hearing listeners. For conditions in which perceptual differences between stimulus items were restricted either by the choice of conditions or by the effects of sensorineural hearing loss, the method of paired comparisons was the more sensitive procedure.

Adult↗
PubMed1996

Comparison of probe insertion methods on estimates of ear canal SPL.

Real-ear sound pressure levels (SPLs) were compared among three methods used for positioning a probe microphone in the ear canal. The probe insertion techniques included (1) an acoustic method that incorporates use of the quarter-wave anti-resonance property of the ear to determine acoustically the location of the probe tube relative to the eardrum; (2) a constant insertion depth method (25 mm from the intratragal notch); and (3) the earmold +5-mm method, which places the probe 5 mm beyond the tip of the earmold, thereby avoiding problems associated with the transition region where sound exits from the bore of the earmold into the larger ear canal. Measurements were obtained at 32 test frequencies in 24 adults with normal middle ear impedance. Results indicated that the SPLs measured by the acoustic method were modestly higher than those measured by the other two methods. This result was most evident in subjects with long ear canals (> 25 mm) and at high test frequencies (3.0 to 6.3 kHz).

Amplifiers, Electronic↗
PubMed1995

Speech recognition in amplitude-modulated noise of listeners with normal and listeners with impaired hearing.

The effect of amplitude-modulated (AM) noise on speech recognition in listeners with normal and impaired hearing was investigated in two experiments. In the first experiment nonsense syllables were presented in high-pass steady-state or AM noise to determine whether the release from masking in AM noise relative to steady-state noise was significantly different between normal-hearing and hearing-impaired subjects when the two groups listened under equivalent masker conditions. The normal-hearing subjects were tested in the experimental noise under two conditions: (a) in a spectrally shaped broadband noise that produced pure tone thresholds equivalent to those of the hearing-impaired subjects, and (b) without the spectrally shaped broadband noise. The release from masking in AM noise was significantly greater for the normal-hearing group than for either the hearing-impaired or masked normal-hearing groups. In the second experiment, normal-hearing and hearing-impaired subjects identified nonsense syllables in isolation and target words in sentences in steady-state or AM noise adjusted to approximate the spectral shape and gain of a hearing aid prescription. The release from masking was significantly less for the subjects with impaired hearing. These data suggest that hearing-impaired listeners obtain less release from masking in AM noise than do normal-hearing listeners even when both the speech and noise are presented at levels that are above threshold over much of the speech frequency range.

Adult↗
PubMed1995

Reliability and sensitivity of paired comparisons and category rating in children.

Children's subjective judgments of speech clarity using the methods of paired comparisons and category rating were evaluated in this investigation. Eighty children with normal hearing between the ages of 4 and 8 years judged the clarity of sentences that were systematically bandpass-filtered using conditions that increased intelligibility as estimated by the Articulation Index. Subjects were classified into four age groups (4-, 5-, 6-, and 7-8-year age groups) with 20 subjects per group. With use of materials and training methods suitable for children, judgments were obtained via the two psychophysical procedures (10 subjects per age group for each procedure). Results indicated that children 5 years of age and older were able to make reliable clarity judgments using either procedure; however, the method of paired comparisons was more sensitive than category rating in detecting differences between the bandpass-filtered conditions.

Age Factors↗
PubMed1994

Effects of probe insertion depth on real ear measurements.

The purpose of this article is to provide an overall summary of the role probe insertion depth has on real ear measurements, and to compare the real ear sound pressure level measured by a probe microphone system, using three methods for positioning the probe in an ear canal. The probe insertion techniques that were compared included: (1) an acoustic method that incorporates use of the quarter-wave antiresonance property of the ear to determine acoustically the location of the probe tube relative to the eardrum in an individual ear; (2) a constant insertion depth method (25 mm from the intratragal notch); and (3) the earmold +5 mm method, which places the probe 5 mm beyond the tip of the individual's earmold in the canal, thereby avoiding problems associated with the transition region, where sound exits from the bore of the earmold into the larger ear canal. Measurements were obtained for each method at 32 frequencies in the unoccluded ears of 17 subjects. Results indicated that the sound pressure levels measured by the acoustic method were significantly larger than those measured by the other two methods. This result was most evident in subjects with long ear canals (> 25 mm) and at high test frequencies (4.0 to 6.3 kHz). For subjects with short or average length ear canals, the three methods provided essentially equivalent results.

Adult↗
PubMed1991

Paired comparison judgments for hearing aid selection in children.

Three experiments were conducted to investigate the feasibility of using a paired comparison technique to select hearing aids for children. The first two experiments determined the age at which normal-hearing children and hearing-impaired children with mild to moderately severe sensorineural hearing loss could be expected to meet criteria on a paired comparison task involving judgments of auditory clarity. Of 25 normal-hearing children between the ages of 4.0 and 6.4 yr, five out of five children between 6.0 and 6.4 yr of age passed the auditory paired comparison task. Of 10 hearing-impaired children between the ages of 5.5 and 7.4 yr, five out of five children between 6.5 and 7.4 yr of age passed the auditory paired comparison task. In Experiment 3, eight hearing-impaired children between the ages of 5.7 and 7.8 yr judged the clarity of seven hearing aids in two paired comparison, round robin tournaments. The results showed that correlations between the two tournaments were moderate to strong for six children and weak for two children. Of the six children with stronger correlations between tournaments, correlations between paired comparison judgments and phoneme identification scores were moderate to strong for four children and weak for two children. When compared with a hearing aid that approximated a standard prescription, the hearing aid selected by the paired comparison technique neither degraded nor enhanced speech intelligibility. Results from this study indicate that a paired comparison technique is feasible for use with hearing-impaired children 6.5 yr of age, and occasionally younger, who exhibit mild to moderately severe sensorineural hearing loss and are capable of performing the task reliably.

Age Factors↗
PubMed1987

Electrical stimulation of the auditory brain stem structure in deafened adults.

Electrical stimulation of the cochlear nuclear complex in the brain stem was first accomplished in a female adult deafened by bilateral acoustic tumors. The central electroauditory prosthesis (CEP) was surgically placed at the time of the second tumor removal. The patient has now been receiving electrical stimulation for 5 years. Six more adults have received the CEP at the time of tumor surgery. Clinical results indicate fluctuations in electrical measurements over time, particularly in the first weeks following surgery. Patients are able to sustain tone perception for one minute at all frequencies tested. Auditory discrimination test results reveal above-chance performance on suprasegmental measures, similar to scores achieved by cochlear implant users. No serious complications have occurred to date.

Adult↗
PubMed1987

Our experience with cochlear implants: have we erred in our expectations?

Many clinicians feel that single-channel cochlear implants are limited in the information they can provide. This has led to some common misconceptions regarding single-channel and multichannel systems. At the House Ear Institute, a growing number of children with the 3M/House single-channel implant are demonstrating open-set understanding of speech on measures designed to test such abilities in children. As a result, we have revised our thinking regarding the potential of this device.

Adolescent↗
PubMed1984

Electrical stimulation of the auditory system in children deafened by meningitis.

Twenty-five children deafened by meningitis were compared with 10 congenitally deaf children on cochlear implant performance. All subjects had met the audiologic criterion of profound deafness as required for implant surgery. Twenty subjects in the meningitis group had some degree of ossification at the round window, and drilling was required for electrode insertion into the scala tympani. In six of these subjects, bone completely filled the scala. There was a significant relationship between extensive ossification and the etiologic pathogen Diplococcus pneumoniae, as determined by radiologic and surgical reports. Postoperative results revealed that all subjects could be electrically stimulated, except for one with extensive bone formation. On implant performance, the meningitis group demonstrated sound-field thresholds comparable to those of the group with congenital deafness but required significantly higher voltage settings. These findings suggest that even with extensive labyrinthine ossification caused by meningitic deafness, neural elements are present and can be stimulated if enough power can be safely provided.

Child↗
PubMed1984

Tone decay in subjects with the single-channel cochlear implant.

Tone decay was studied in a group of 17 profoundly deaf adults who have a single-channel cochlear implant. With direct electrical input through the subject's induction coil system, tone decay was evaluated at 125, 250, 500, 2 000, 4 000, and 16 000 Hz. Results indicated that as the intensity of electrical stimulation increased, the ability to perceive a continuous signal also increased for the majority of the subjects. All but 3 of the subjects were able to perceive the electrical signal at suprathresholds for 2 min. The 3 subjects who exhibited tone decay differed from the rest of the sample in several ways: (1) they became deaf at an earlier age; (2) they had more years of profound deafness, and (3) they had fewer years of cochlear implant and hearing aid use.

Adult↗
PubMedDate not supplied

Cochlear implants in children.

In recent years, the House single-electrode cochlear implant has proven to be a clinically feasible prosthesis for profoundly deaf adults. Based on these findings, the decision was made to begin implanting those children who could not benefit from hearing aids. As of August 1982, 23 profoundly deaf children (ranging in age from 3.4 to 17.5 yrs) have received the cochlear implant. The majority were deafened by meningitis. Results to date indicate that children demonstrate sound field thresholds and receive timing/intensity information comparable to that of adult implant patients. Results have been extremely encouraging, but only long-term experience will determine the ultimate benefit of the implant in children.

Adolescent↗