Self-report and long-term field measures of MP3 player use: how accurate is self-report?

OBJECTIVE: This study was designed to evaluate the usage patterns of portable listening device (PLD) listeners, and the relationships between self-report measures and long-term dosimetry measures of listening habits. DESIGN: This study used a descriptive correlational design. STUDY SAMPLE: Participants (N = 52) were 18-29 year old men and women who completed surveys. A randomly assigned subset (N = 24) of participants had their listening monitored by dosimetry for one week. RESULTS: Median weekly noise doses reported and measured through dosimetry were low (9-93%), but 14.3% of participants reported exceeding a 100% noise dose weekly. When measured by dosimetry, 16.7% of participants exceeded a 100% noise dose weekly. The self-report question that best predicted the dosimetry-measured dose asked participants to report listening duration and usual listening level on a visual-analog scale. CONCLUSIONS: This study reports a novel dosimetry system that can provide accurate measures of PLD use over time. When not feasible, though, the self-report question described could provide a useful research or clinical tool to estimate exposure from PLD use. Among the participants in this study, a small but substantial percentage of PLD users incurred exposure from PLD use alone that increases their risk of music-induced hearing loss.

The Marion Downs National Center for Infant Hearing: developing comprehensive state systems.

The Marion Downs National Center for Infant Hearing was established in 1996 through a Maternal and Child Health Grant awarded to the University of Colorado. The goals of the grant are to implement statewide systems of newborn hearing screening, audiologic assessment, and early intervention in 19 states. Newborn hearing screening alone will not assure early identification or positive outcomes for the development of communication and language. Therefore, the staff at the Marion Downs National Center developed comprehensive goals for all participating states. These goals are described in this article.

A comparison of monotic and dichotic complex-tone pitch perception in listeners with hearing loss.

The perception of fundamental pitch for two-harmonic complex tones was examined in musically experienced listeners with cochlear-based high-frequency hearing loss. Performance in a musical interval identification task was measured as a function of the average rank of the lowest harmonic for both monotic and dichotic presentation of the harmonics at 14 dB Sensation Level. Listeners with hearing loss demonstrated excellent musical interval identification at low fundamental frequencies and low harmonic numbers, but abnormally poor identification at higher fundamental frequencies and higher average ranks. The upper frequency limit of performance in the listeners with hearing loss was similar in both monotic and dichotic conditions. These results suggest that something other than frequency resolution per se limits complex-tone pitch perception in listeners with hearing loss.

The role of educators of the deaf in the early identification of hearing loss.

About 16,000 babies each year will be identified with hearing loss by age 3 months once universal newborn hearing screening becomes a reality. Identification of hearing loss in infancy, followed by appropriate intervention by age 6 months, can result in normal language development, regardless of degree of hearing loss. As the average age of identification of hearing loss moves downward toward 2 months, children with hearing loss will enter the educational system earlier and with language skills commensurate with those of their hearing peers. In order to provide appropriate services to children with hearing loss and their families, early interventionists will need to forge links to health care providers involved in universal newborn hearing screening programs, to have specialized training in deafness and hearing loss, and to have expertise in providing services to very young children and to children with hearing loss in the broad range from mild to profound.

Psychometric functions for discrimination of two-component complex tones in listeners with normal hearing and listeners with hearing loss.

This study compared the ability of 5 listeners with normal hearing and 12 listeners with moderate to moderately severe sensorineural hearing loss to discriminate complementary two-component complex tones (TCCTs). The TCCTs consist of two pure tone components (f1 and f2) which differ in frequency by delta f (Hz) and in level by delta L (dB). In one of the complementary tones, the level of the component f1 is greater than the level of component f2 by the increment delta L; in the other tone, the level of component f2 exceeds that of component f1 by delta L. Five stimulus conditions were included in this study: fc = 1000 Hz, delta L = 3 dB; fc = 1000 Hz, delta L = 1 dB; fc = 2000 Hz, delta L = 3 dB; fc = 2000 Hz, delta L = 1 dB; and fc = 4000 Hz, delta L = 3 dB. In listeners with normal hearing, discrimination of complementary TCCTs (with a fixed delta L and a variable delta f) is described by an inverted U-shaped psychometric function in which discrimination improves as delta f increases, is (nearly) perfect for a range of delta f's, and then decreases again as delta f increases. In contrast, group psychometric functions for listeners with hearing loss are shifted to the right such that above chance performance occurs at larger values of delta f than in listeners with normal hearing. Group psychometric functions for listeners with hearing loss do not show a decrease in performance at the largest values of delta f included in this study. Decreased TCCT discrimination is evident when listeners with hearing loss are compared to listeners with normal hearing at both equal SPLs and at equal sensation levels. In both groups of listeners, TCCT discrimination is significantly worse at high center frequencies. Results from normal-hearing listeners are generally consistent with a temporal model of TCCT discrimination. Listeners with hearing loss may have deficits in using phase locking in the TCCT discrimination task and so may rely more on place cues in TCCT discrimination.

Just noticeable differences for glottal flow waveform characteristics.

This study was primarily motivated by the need to establish the correspondence between auditory abilities and laryngeal function. Just noticeable differences (JNDs) were obtained for the open quotient and speed quotient of the glottal flow waveform. The quotients were synthesized for both the glottal flow alone, and for the output pressure signal after the glottal flow signal was applied to the synthesis vocal tract for the vowel /a/. Six adult men and five adult women, all teachers of singing, participated as listeners. An adaptive auditory listening procedure was used to estimate JNDs for the four types of stimuli. The group average JND values were as follows. For the standard open quotient value of .6000, JND = 0.0264 (SD = .010) for the glottal flow and JND = 0.0344 (SD = .020) for the output pressure. For the open quotient, there was no statistically significant difference between genders or between the types of signals. For the standard speed quotient value of 2.000, JND = 0.154 (SD = .043) for the glottal flow and JND = 0.319 (SD = .167) for the output pressure. For the speed quotient, there was no statistically significant difference between genders, but the difference between types of stimulus (glottal flow versus output pressure) was significant (p < .006). The variance among the JND values was significantly larger for the output pressure stimuli compared to the glottal flow stimuli for both the open quotient and the speed quotient.

Role of fundamental frequency differences in the perceptual separation of competing vowel sounds by listeners with normal hearing and listeners with hearing loss.

This study compared the ability of listeners with normal hearing and listeners with moderate to moderately-severe sensorineural hearing loss to use fundamental frequency differences (delta F0) in the identification of monotically presented simultaneous vowels. Two psychophysical procedures, double vowel identification and masked vowel identification, were used to measure identification performance as a function of delta F0 (0 through 8 semitones) between simultaneous vowels. Performance in the double vowel identification task was measured by the percentage of trials in which listeners correctly identified both vowels in a double vowel. The masked vowel identification task yielded thresholds representing signal-to-noise ratios at which listeners could just identify target vowels in the presence of a masking vowel. In the double vowel identification task, both listeners with normal hearing and listeners with hearing loss showed significant delta F0 benefit: Between 0 and 2 semitones, listeners with normal hearing showed an 18.5% average increase in performance; listeners with hearing loss showed a 16.5% average increase. In the masked vowel identification task, both groups showed significant delta F0 benefit. However, the mean benefit associated with delta F0 differences in the masked vowel task was more than twice as large in listeners with normal hearing (9.4 dB) when compared to listeners with hearing loss (4.4 dB), suggesting less delta F0 benefit in listeners with hearing loss. In both tasks, overall performance of listeners with hearing loss was significantly worse than performance of listeners with normal hearing. Possible reasons for reduced delta F0 benefit and decreased overall performance in listeners with hearing loss include reduced audibility of vowel sounds and deficits in spectro-temporal processing.

Effects of harmonic content on complex-tone fundamental-frequency discrimination in hearing-impaired listeners.

Complex-tone (fundamental) frequency discrimination was measured in eight well-trained listeners with moderately severe sensorineural hearing impairments as a function of parametric variations in the rank, number, and sensation level of stimulus components. Results indicate substantial differences in the effects of harmonic content on complex-tone frequency discrimination among hearing-impaired listeners and between hearing-impaired and normal-hearing listeners. Despite large variability among the hearing-impaired subjects, several patterns of results emerged: Performance of two subjects grew worse as harmonic rank increased; performance of three subjects did not change substantially with changes in harmonic rank; and performance of three impaired subjects improved as harmonic rank increased. Performance of all but two subjects was significantly degraded for stimuli containing low-order harmonics. For stimuli containing only high-order harmonics, five subjects showed performance that was comparable to that of normal-hearing subjects, and three showed abnormally poor performance. Performance of impaired subjects generally improved as the number of stimulus components increased. The sensation level of stimulus components influenced the performance of several impaired subjects, but not in a uniform manner. To the extent that complex-tone fundamental-frequency discrimination can be assumed to be a pitch perception task, the present results suggest that, in contrast to normal-hearing subjects, hearing-impaired listeners rely primarily on periodicity cues in the perception of complex-tone pitch.

Longitudinal measurements of spontaneous otoacoustic emissions in infants.

It has previously been shown [E. M. Burns, K. H. Arehart, and S. L. Campbell, J. Acoust. Soc. Am. 91, 1575-1581 (1992)] that both the overall prevalence of spontaneous otoacoustic emissions (SOAEs) and most of the various gender- and ear-related prevalence tendencies are not significantly different in 1-month-olds and adults. However, large differences were found between the neonates and adults in the distributions of the frequencies and levels of SOAEs. Both the average level and the median frequency were significantly higher in infants. To obtain longitudinal SOAE data, infants from this original group of 1-month-olds were tested at ages 3, 6, 12, and 24 months. In general, individual SOAEs decrease in level with age, and high-frequency SOAEs tend to show the largest decreases. No substantial shifts occur in the frequencies of individual SOAEs. The frequency and level distributions at 24 months of age are still not adult-like. SOAEs which show short-term instabilities in frequency and/or amplitude at 1 month of age typically continue to evidence such instabilities at later ages. These results suggest the cochlea is adult-like at birth, and imply that the observed SOAE changes reflect developmental changes in the external and middle ear.

Ear-canal impedance and reflection coefficient in human infants and adults.

The ear-canal impedance and reflection coefficient were measured in an adult group and in groups of infants of age 1, 3, 6, 12, and 24 months over frequency range 125-10,700 Hz. The development of the external ear canal and middle ear strongly affect input impedance and reflection coefficient responses, and this development is not yet complete at age 24 months. Contributing factors include growth of the area and length of the ear canal, a resonance in the ear-canal walls of younger infants, and a probable influence of growth of the middle-ear cavities. The middle-ear compliance is lower in infants than adults, and the middle-ear resistance is higher. The power transfer into the middle ear of the infant is much less than into that of the adult. Such differences in power transfer directly influence both behavioral and physiological measurements of hearing. The difficulties of interpretation of neonatal tympanograms are shown to be a consequence of ear-canal wall vibration. Impedance and reflectance measurements in the 2-4-kHz range are recommended as a potentially useful clinical tool for circumventing these difficulties.

Prevalence of spontaneous otoacoustic emissions in neonates.

The prevalence of spontaneous otoacoustic emissions (SOAEs) was measured in a group of 100 neonates and in a group of 50 normal-hearing young adults. The prevalence of SOAEs in the adult group (0.62) is at the high end of the range of prevalences reported in other surveys of adult SOAEs based on measurements using similar microphones. The prevalence of SOAEs in neonates (0.64) is not significantly different from that in adults. The various tendencies that have been found to be significant in the pooled results of other surveys are also evident in our adult group: more SOAEs in right ears, a higher prevalence of SOAEs in females, and a dependence between ears for the occurrence of SOAEs. The above-mentioned tendencies are also significant in the infant data. The major differences between the infant and adult results are the predominant SOAE frequency range and the average levels of SOAEs. The majority of adult SOAEs are between 1.0 and 2.0 kHz, whereas the majority of neonatal SOAEs are between 2.5 and 5.0 kHz. The average SOAE level is -2.6 dB SPL for adults and 8.5 dB SPL for infants.

A comparison of psychometric functions for detection in normal-hearing and hearing-impaired listeners.

Psychometric functions (PFD) for the detection of pure tones were obtained with a two-interval forced-choice procedure from a group of listeners with normal hearing and a group of listeners with sensorineural impairments of presumed cochlear origin. Five PFDs were obtained for each group at each of the four test frequencies (500, 2000, 4000, and 8000 Hz). The slopes of PFDs were abnormally steep in some of the hearing-impaired listeners, but were statistically significant only at 2000 Hz.