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Biomedical subjects

R W Keith

Publications and source records attributed to R W Keith.

52 records · Page 3Linked to original sources
PubMed1976

Acoustic impedance measurement in the otological assessment of multiply handicapped children.

This survey investigated the use of acoustic impedance measurement on a population of multiply handicapped children and correlated the results with otoscopy. Thirty-one children were tested with an impedance meter studying tympanometry, tympanic membrane compliance, and acoustic reflex. Otoscopic examination was also scheduled for each child. The results show that 42% of children tested had some kind of middle-ear problem, mostly unrecognized at the time of this survey. There was 100% agreement between impedance and otoscopic findings. Apparently impedance audiometry can be useful for identifying middle-ear disorders in children who cannot be tested by traditional audiometric methods.

Acoustic Impedance Tests↗
PubMed1975

Middle ear function in neonates.

This study was designed to investigate the middle ear function of neonates during the first few hours of life. Twenty normal babies, ranging in age from 2.5 to 20 hours old, were tested witn an electroacoustic impedance bridge. Measurements of the acoustic compliance of the tympanic membrane and tympanometry were obtained on both ears of each child. Results of compliance measurements indicated a median of 1,2 cu cm with a range of 0.25 to 1.65 cucm. Tympanometry results showed smooth notched-shaped tympanograms in most cases although afew M-shaped tympanograms were observed. All of the infants demonstrated normal middle ear pressures and mobile middle ear systems. The finding of normal middle ear function in these neonates suggest that mucus is not commonly present and therefore not a factor in infants' response to sound.

Compliance↗
PubMedDate not supplied

Lead exposure and the central auditory processing abilities and cognitive development of urban children: the Cincinnati Lead Study cohort at age 5 years.

This analysis examined the relationship between lead exposure as registered in whole blood (PbB) and the central auditory processing abilities and cognitive developmental status of the Cincinnati cohort (N = 259) at age 5 years. Although the effects were small, higher prenatal, neonatal, and postnatal PbB levels were associated with poorer central auditory processing abilities on the Filtered Word Subtest of the SCAN (a screening test for auditory processing disorders). Higher postnatal PbB levels were associated with poorer performance on all cognitive developmental subscales of the Kaufman Assessment Battery for Children (K-ABC). However, following adjustment for measures of the home environment and maternal intelligence, few statistically or near statistically significant associations remained. Our findings are discussed in the context of the related issues of confounding and the detection of weak associations in high risk populations.

Auditory Perceptual Disorders↗
PubMedDate not supplied

Filtered word testing in the assessment of children's central auditory abilities.

The purpose of this study was to evaluate the effects of various cut-off frequencies on low-pass filtered speech discrimination test results obtained from children. Two groups of children, one presumed to have normal auditory perception and the other with auditory learning disabilities, were tested. Phonetically Balanced Kindergarten word list words were low-pass filtered at 1000 Hz, 750 Hz, and 500 Hz. The results indicate a clear separation of groups for the 1000 Hz filtered condition only. The implications of these preliminary test findings are discussed.

Auditory Diseases, Central↗
PubMedDate not supplied

Relationship between two dichotic listening tests and the Token test for children.

The relationship between two dichotic listening tasks was studied. The two dichotic tests used were the Staggered Spondaic Word (SSW) test and the directed Dichotic Consonant-Vowel (CV) test. These measures were administered to 104 children between the ages of 6.0 and 8.0 yrs. The subjects were divided into two groups according to their Token test scores with group I having normal Token test scores and group II having below average scores on the Token test. When the performances of the two groups on the SSW test were compared, a significant difference was found between them on the right and left competing conditions of the test. There was no difference between the groups on any response bias. On the directed Dichotic CV test the two groups were significantly different on the right ear scores but not on the left ear scores under both directed conditions. The groups were also significantly different on the directed right task when the difference between the two ear scores was compared but not on the directed left task. It was concluded that there is a relationship between these two dichotic measures and the Token Test for Children.

Auditory Pathways↗
PubMedDate not supplied

Interpretation of the Staggered Spondee Word (SSW) test.

The Staggered Spondee Word (SSW) test is a dichotic listening test that has been frequently used in the evaluation of auditory perceptual abilities in children with language and learning problems. Interpretation of this test is based on scores obtained under noncompeting and competing portions of the test stimuli, and on response biases that include ear and order effects, reversals, the type A pattern, and the total bias score. Alternate methods of interpreting SSW results are suggested. Data obtained on 57 children referred for central auditory and language testing are presented for illustration.

Adolescent↗
PubMedDate not supplied

Performance of adults on directed listening tasks using a dichotic CV test.

The purpose of this study was to examine the response of adult subjects to directed listening tasks, using the dichotic consonant-vowel (CV) identification test. Twenty-five subjects, 20 to 36 years of age, were tested. Dichotic CV testing was administered utilizing the directed listening paradigm and free recall instructions. Results indicated that subjects showed right ear advantage in the directed right listening condition, and left ear advantage in directed left listening condition. Free recall listening conditions showed a right ear advantage. These results show a previously unreported maturational effect on dichotic CV testing. Implications of test findings are discussed.

Adult↗
PubMedDate not supplied

Auditory processing abilities in children with previous middle ear effusion.

The present study was designed to determine whether auditory processing disorders are present in children with documented middle ear effusion (MEE) that required surgical treatment. Children with previous MEE and control subjects, in two age groups, were studied using five tests of auditory processing abilities: low-pass filtered speech, staggered spondaic word test, speech in noise, auditory sequential memory, and sound blending. Results found differences in groups at mean age 7 on the filtered speech tests, but no statistical differences were found on any other test at age 7 or on any test at mean age 9. The results indicate that well-managed MEE appears to have no long-term effects on children acquiring this disease.

Auditory Perceptual Disorders↗
PubMedDate not supplied

An effect of linguistic experience. Auditory word discrimination by native and non-native speakers of English.

In this study, the effect of linguistic experience on the auditory discrimination of words has been examined. 18 subjects, including 6 native and 12 non-native speakers of English, were tested with CID auditory test W-22 in quiet and in the presence of white noise at the signal-to-noise (S/N) ratios of +12, +6 and 0 dB. The non-native speakers of English included 6 with 1 year of experience and 6 with 3-4 years of experience speaking Enligsh in the USA. In the absence of noise, the results were essentially equivalent for all three groups. As noise level increased, word discrimination deteriorated for all three groups with non-native speakers of English obtaining results significantly poorer than native speakers of English. Linguistic experience and noise levels were significant at the 0.001 level fo confidence. It appears that at 0 dB S/N, individual variability of non-native speakers of English, regardless of their original linguistic background, was much smaller than that found for native speakers of English. The results of the study tend to indicate that a limited linguistic experience results in a persistent deterioration of auditory word discrimination under impoverished conditions of audition.

Adult↗
PubMedDate not supplied

Loudness and the acoustic reflex: normal-hearing listeners.

The relationships among most comfortable listening level (MCL), loudness discomfort level, and the acoustic reflex to speech were studied on normal-hearing listeners using earphones and sound field test conditions. Recorded sentence materials were presented monaurally in quiet and, in the sound field, in the presence of 55 dB SPL cafeteria noise. The results indicate the MCL in the quiet sound field at approximately 70 dB SPL with the acoustic reflex occurring at 16 dB higher intensity. The earphone MCL was 7 dB lower than in the sound field, a finding that may reflect a real reverse in usual earphone/sound field results or simply calibration factors particular to the speakers and test room used in this study. The AR to speech seems to occur at approximately equal intensities between the MCL and LDL tested in quiet. The MCL is elevated by noise whereas the acoustic reflex remains at a constant level, indicating that no absolute relationship exists between loudness and the AR.

Acoustic Impedance Tests↗
PubMedDate not supplied

Loudness and the acoustic reflex: cochlear-impaired listeners.

The relationships among most comfortable listening level (MCL), loudness discomfort level, and the acoustic reflex (AR) to speech were studied on cochlear-impaired listeners using earphones and sound field conditions. Recorded sentence materials were presented monaurally in quiet and in the sound field in the presence of 55 dB SPL cafeteria noise. Both unaided and aided sound field testing were done. The results indicated that the MCL and AR fell at approximately the same intensities under all test conditions, whereas the LDL occurred at approximately 18 dB higher intensity. The MCL was elevated by the presence of noise, whereas the AR remained invariant. Also, the AR occurred below the level predicted by the loudness function. The results tend to indicate that although the AR is highly correlated with MCL in cochlear-impaired listeners a cause and effect relationship may not exist.

Adolescent↗
PubMedDate not supplied

An acoustic reflex technique of establishing hearing aid settings.

An acoustic reflex method of establishing hearing aid gain settings for most comfortable loudness was tested. Forty hearing-aid users were examined to determine relationships among MCL, loudness discomfort level, and the contralateral acoustic reflex to speech, under unaided and aided conditions. Results indicate that a simple 2-part rule results in amplification to most comfortable loudness for 76% of subjects. Implications for establishing hearing aid saturation sound pressure level settings are discussed.

Adolescent↗