Biomedical subjects

C C Crandell

Publications and source records attributed to C C Crandell.

9 recordsLinked to original sources

PubMed1999

Effects of sound-field frequency modulation amplification on reducing teachers' sound pressure level in the classroom.

Voice problems are a frequent difficulty that teachers experience. Common complaints by teachers include vocal fatigue and hoarseness. One possible explanation for these symptoms is prolonged elevations in vocal loudness within the classroom. This investigation examined the effectiveness of sound-field frequency modulation (FM) amplification on reducing the sound pressure level (SPL) of the teacher's voice during classroom instruction. Specifically, SPL was examined during speech produced in a classroom lecture by 10 teachers with and without the use of sound-field amplification. Results indicated a significant 2.42-dB decrease in SPL with the use of sound-field FM amplification. These data support the use of sound-field amplification in the vocal hygiene regimen recommended to teachers by speech-language pathologists.

Adult↗

PubMed1998

Reliability issues with the Synthetic Sentence Identification test.

This investigation examined the reliability of the Synthetic Sentence Identification (SSI) test. An adaptive procedure was used to assess speech recognition thresholds (SRTs) for the SSI lists over two separate test sessions. The commercially available Davy Crockett passage and a multitalker babble were used as competition. Subjects consisted of 20 adults with normal hearing sensitivity. Results indicated (1) significantly higher SRTs with the multitalker babble, (2) significant differences in SRTs among SSI lists when using the Davy Crockett competition, (3) no significant learning/practice or fatigue effects across trials in either noise condition, and (4) high test-retest reliability across test sessions. Clinical implications of these data are considered.

Adolescent↗

PubMed1997

Middle ear pressure variation: effect of nitrous oxide.

Previous studies examining middle ear pressure changes due to inhalant anesthesia, including nitrous oxide, have cited equivocal results. An investigation was performed to closely monitor changes in middle ear pressure during middle ear surgery. Baseline tympanometry was performed before anesthesia, and middle ear pressure was then documented in 1-min time intervals. A total of 97 subjects were studied; 51 received nitrous oxide and halothane, and 46 received halothane alone. Results indicate that nitrous oxide causes significantly greater pressure fluctuations than halothane alone. There were no effects for time of surgery, type of fluid, or baseline. Pressure fluctuation was attributed to eustachian tube function. Case studies are presented to demonstrate subject variability, and suggestions for validation study procedures are presented.

Acoustic Impedance Tests↗

PubMed1995

Speech recognition in noise by hearing-impaired and noise-masked normal-hearing listeners.

A prevailing complaint among individuals with sensorineural hearing loss (SNHL) is difficulty understanding speech, particularly under adverse listening conditions. The present investigation compared the speech-recognition abilities of listeners with mild to moderate degrees of SNHL to normal-hearing individuals with simulated hearing impairments, accomplished using spectrally shaped masking noise. Speech-perception ability was assessed using the predictability-high sentences from the Speech Perception in Noise test. Results revealed significant differences between groups in sentential-recognition ability, with the hearing-impaired subjects performing poorer than the masked-normal listeners. These findings suggest the presence of a secondary distortion degrading sentential-recognition ability in the hearing impaired, implications of these data will be discussed concerning the mechanism(s) responsible for speech perception in the hearing impaired.

Adult↗

PubMed1993

Speech recognition in noise by children with minimal degrees of sensorineural hearing loss.

It is well recognized that the acoustical environment in a classroom is an important variable in the psychoeducational achievement of hearing-impaired children. To date, however, there remains a paucity of information concerning the importance of classroom acoustics for children with minimal degrees of sensorineural hearing loss (SNHL). The present investigation examined the effects of commonly reported classroom signal to noise ratios (+6, +3, 0, -3, and -6 dB) on the sentence recognition of 20 normal-hearing children and 20 children with minimal degrees of SNHL (i.e., pure-tone averages of 15-30 dB HL through the speech frequency range). Results indicated that children with minimal degrees of SNHL obtained poorer recognition scores than normal-hearing children across most listening conditions. Moreover, the performance decrement between the two groups increased as the listening environment became more adverse. Educational implications of these data, such as acoustical modification of the classroom and/or the utilization of frequency modulation sound field amplification systems, are discussed.

Acoustic Stimulation↗

PubMed1993

Incidence of excessive/impacted cerumen in individuals with mental retardation: a longitudinal investigation.

A major sequelae of impacted cerumen (earwax) is conductive hearing loss, which can be deleterious to linguistic, social, and intellectual development, particularly for individuals with mental retardation. The longitudinal incidence (12-year period) of excessive/impacted cerumen and related conductive hearing loss of 117 adults with mental retardation was examined. Results indicated a considerably higher incidence of excessive cerumen and cerumen impaction with associated conductive hearing loss in adults with mental retardation (28%) than in the general adult population (2% to 6%). Moreover, a strong propensity for recurrent cerumen impaction in the mentally retarded population was found. These findings were discussed in view of the management of cerumen impaction among individuals with mental retardation.

Adult↗

PubMed1991

Individual differences in speech recognition ability: implications for hearing aid selection.

Hearing-impaired listeners with similar audiometric configurations often demonstrate varying abilities to understand speech in the presence of noise and/or reverberation. To date, however, it is unclear which auditory mechanisms are responsible for these perceptual deficits. This lack of information is unfortunate, as individual susceptibility to noise and reverberation may explain why hearing-impaired listeners receive varying degrees of benefit from rehabilitative strategies. The present discussion will examine: (1) individual speech recognition susceptibility to noise and reverberation in hearing-impaired listeners and (2) auditory and cognitive hypotheses to explain individual differences in speech recognition performance. Theoretical and clinical implications for hearing aid selection procedures will be discussed.

Hearing Aids↗

PubMed1986

Acoustic radiation produced by B-71, B-72, and KH 70 bone vibrators.

The amount of acoustic radiation produced by two samples of a Radioear B-71, B-72, and Pracitronic KH 70 bone vibrator was determined for 30 normal-hearing subjects at 4000 Hz. The mean amount of acoustic radiation was very similar for both samples of each vibrator type but significantly (p less than 0.05) different between the bone vibrator types. The mean amount of acoustic radiation averaged over both samples was 8.3 dB for the B-72, 4.3 dB for the B-71, and -0.3 dB for the KH 70. Individual subject data indicated that the B-72 produced excessive acoustic radiation (greater than 5 dB) for 80% of the subjects, the B-71 for 38% of the subjects, and the KH 70 for 8% of the subjects which could cause an invalid high-frequency air-bone gap. Precautions should be taken during bone conduction audiometry to eliminate the possibility of acoustic radiation produced by bone vibrators. A need for additional standards in this area is stressed.

Acoustics↗

PubMed1986

An update on amplification: some changing directions.

This report reviews some of the developments and changes that are occurring in the field of amplification. The discussion focuses on such areas as hearing aid rules and regulations, hearing aid sales and dispensing practices, hearing aid technology, and selection and evaluation procedures.

Hearing Aids↗