Exploring auditory temporal resolution and dichotic listening skills among individuals with type 2 diabetes mellitus.

The study aimed to explore the auditory temporal resolution and dichotic listening skills in patients with type 2 diabetes mellitus (T2DM) and identify associated health-related factors. Using a cross-sectional design, 87 adults with T2DM and 48 non-diabetic controls, all with normal hearing, participated. The two central auditory processing (CAP) skills were assessed through the Gaps-In-Noise (GIN) and Dichotic-Digits Listening (DDL) tests. T2DM participants underwent blood tests to measure various health-related factors. In the GIN test, the shortest gap threshold (GapTh) obtained across both ears was significantly higher in the diabetic group (9.1 ± 2.4 ms) compared to the non-diabetic group (7.5 ± 1.5 ms), and the score of correctly identified gaps (GapSc) in the diabetic group (45±11 %) was significantly lower than GapSc in the non-diabetic group (52±9 %), p < 0.001. In the DDL test, the free-recall score (73.8 ± 18.5 %) across both ears and the right-ear advantage (-1.3 ± 20.6 %) in the diabetic group were significantly lower than the free-recall score (85.8 ± 11.9 %) and right-ear advantage (6.9 ± 11.9 %) in the non-diabetic group, p < 0.005. Furthermore, the duration of diabetes, eGFR level, retinopathy, carotid plaque, fasting blood glucose level, and HDL-C (good cholesterol) level were factors significantly associated with performances in the GIN and/or DDL tests for T2DM participants. In conclusion, individuals with T2DM are at risk of reduced auditory processing skills in temporal resolution and dichotic listening, impacting their speech understanding. Six health-related factors were identified as significantly associated with CAP skills in T2DM patients.

Influence of Speech Recognition Ability on Acceptable Noise Level for Mandarin (Chinese) Speakers with Normal Hearing.

INTRODUCTION: Noise can induce hearing loss and reduce speech understanding. The Acceptable Noise Level (ANL) test has been widely used in audiology. However, strategies used by listeners to determine ANLs are unclear. The current study evaluated the role of speech recognition in selecting ANL and how well ANL could predict speech understanding in a noisy situation. METHODS: Forty-five Mandarin speakers with normal hearing were tested in both ears. ANL is defined as Most Comfortable Level (MCL) minus Background Noise Level (BNL). To obtain ANL monaurally with an earphone, the study measured participants' MCL to hear a Mandarin story in quiet and the maximum BNL to tolerate while following the story. Then, based on the participant's ANL, speech recognition in noise was examined using a set of phonemic-balanced Mandarin words. The signal-to-noise ratio (SNR) was adjusted to ANL, ANL - 10 dB ("degraded noise condition"), and ANL + 10 dB ("improved noise condition"). RESULTS: The mean ANLs were 2.4 dB and 2.6 dB for the left and right ears, respectively. The mean speech recognition with SNR adjusted to ANL was relatively high for both ears (81-83% correct). Even for those ear samples with very low ANL (<0 dB), speech performance obtained at SNR = ANL was still high. The mean speech recognition obtained at SNR = ANL was 5 percentage points lower than the mean speech recognition at the improved noise condition and 14 percentage points higher than the mean speech recognition at the degraded noise condition. Speech recognition obtained at SNR = ANL and ANL - 10 dB correlated significantly with ANL. CONCLUSION: Speech recognition in noise appears to play an important role for listeners with normal hearing in deciding their ANLs. Additionally, ANL can predict speech performance (r-squared = 53-61%) in the degraded noise condition.

Dichotic listening using Mandarin CV-words of six plosives and vowel /a/.

OBJECTIVE: Available data on dichotic listening using tonal Chinese words have been limited, and conflicting results on a right-ear advantage (REA) have been reported. The current study developed a set of Mandarin CV-words based on the Bergen dichotic listening paradigm. DESIGN: The test materials consisted of two sets of stimuli. The English set, derived from the iDichotic application, consisted of six nonsense syllables with plosives conjugated to /a/. The Mandarin set had these 6 CV-syllables spoken as real words according to the Mandarin phonology. Study sample: Forty young, native Mandarin speakers were tested dichotically with both sets of test materials. Twenty participants were right-handed, and the other twenty were left-handed. Fourteen participants were randomly selected to repeat the test with the Mandarin set. RESULTS: The mean difference of correct recognition responses between two ears indicated a REA with both sets of stimuli for the right-handers, but not for left-handers. For the right-handers, performance with the Mandarin set was significantly better than performance with the English set. Dichotic listening with the Mandarin set had strong correlation between two time points, r = 0.8. CONCLUSIONS: Performance using the Mandarin set is reliable in dichotic listening; a REA is observed for the right-handers.

Factors affecting the Mandarin dichotic digits test.

Objective: Data with regard to the Mandarin dichotic digits test (DDT) are limited, with conflicting results reported between the Mandarin and English DDTs. The current study examined factors that might affect the performance in the Mandarin DDT. Design: The digits were arranged in 3 sets of 20 dichotic pairs; each set comprised 2, 3 or 4 digits in a pair. Study sample: Forty-one young, native Mandarin speakers with normal hearing were tested; 30 of them were right-handed and 11 left-handed. Six participants repeated the test. Results: The prevalence of ceiling effect in recognition score decreased systematically as the digit-pair length increased. At digit sets of 3-pair and 4-pair, the right-handed group showed a significant higher recognition score at right ear than left ear, while the left-handed group reversed the performance. The score difference between ears is significantly different between the right- and left-handed groups. The retest of the Mandarin DDT was reliable. Conclusions: For the right-handed group, a right-ear advantage can exist in the Mandarin DDT at a longer digit-pair length, similar to what was reported in the English DDT. Moreover, for the left-handed group, the attended right hemisphere in processing the tonal digits can result in a left-ear advantage.

Development of the Mandarin speech banana.

Purpose: For Indo-European languages, "speech banana" is widely used to verify the benefits of hearing aids and cochlear implants. As a standardised "Mandarin speech banana" is not available, clinicians in China typically use a non-Mandarin speech banana. However, as Chinese is logographic and tonal, using a non-Mandarin speech banana is inappropriate. This paper was designed to develop the Mandarin speech banana according to the Mandarin phonetic properties. Method: In the first experiment, 14 participants read aloud the standard Mandarin initials and finals. For each pronounced sound, its formants were measured. The boundary of all formants formed the formant graph (intensity versus frequency). In the second experiment, 20 participants listened to a list of pre-recorded initials and finals that had been filtered with different bandwidths. The minimum bandwidth to recognise a target sound defined its location on the formant graph. Result: The Mandarin speech banana was generated with recognisable initials and finals on the formant graph. Tone affected the shape of the formant graph, especially at low frequencies. Conclusion: Clinicians can use the new M andarin speech banana to counsel patients about what sounds are inaudible to them. Speech training can be implemented based on the unheard sounds in the speech banana.

Central conduction time in auditory brainstem response and ear advantage in dichotic listening across menstrual cycle.

The ovarian hormones fluctuate during the menstrual cycle in women. Such fluctuation of sex hormones, in particular estrogen, is believed to affect the central conduction time in auditory function as well as the language lateralization in cognitive function. However, findings are inconsistent. The underlying mechanisms are also unclear. This paper examined if there was any relation between the central conduction time and the language lateralization at different times during the menstrual cycle. Twenty young women with normal menstrual cycle were tested four times (5 to 7 days apart) across the menstrual cycle. The test battery included the electrophysiological measurement of auditory evoked response in brainstem and the speech performance in dichotic listening with monosyllables as stimulus pairs. The dichotic listening task was conducted under the non-forced, forced-right and forced-left attention. The central conduction time was defined by the time elapsed between two auditory elicited responses along the auditory pathway. The language lateralization in dichotic listening was expressed in ear advantage, which was the right-ear score minus the left-ear score. The results showed that the effects of test time were significant on both the central conduction time and the ear advantage under the forced-left attention. Overall, the interaural difference in the central conduction time correlates with the ear advantage (non-forced attention) at the beginning of the menstrual cycle. The change in central conduction time between two test times correlates significantly with the change in ear advantage under the non-forced and forced-left attention. Conclusively, the central conduction time depends on the time during the menstrual cycle, which in turn may affect the performance in dichotic listening.

Tracking of Noise Tolerance to Measure Hearing Aid Benefit.

BACKGROUND: The benefits offered by noise reduction (NR) features on a hearing aid had been studied traditionally using test conditions that set the hearing aids into a stable state of performance. While adequate, this approach does not allow the differentiation of two NR algorithms that differ in their timing characteristics (i.e., activation and stabilization time). PURPOSE: The current study investigated a new method of measuring noise tolerance (Tracking of Noise Tolerance [TNT]) as a means to differentiate hearing aid technologies. The study determined the within-session and between-session reliability of the procedure. The benefits provided by various hearing aid conditions (aided, two NR algorithms, and a directional microphone algorithm) were measured using this procedure. Performance on normal-hearing listeners was also measured for referencing. RESEARCH DESIGN: A single-blinded, repeated-measures design was used. STUDY SAMPLE: Thirteen experienced hearing aid wearers with a bilaterally symmetrical (≤10 dB) mild-to-moderate sensorineural hearing loss participated in the study. In addition, seven normal-hearing listeners were tested in the unaided condition. DATA COLLECTION AND ANALYSIS: Participants tracked the noise level that met the criterion of tolerable noise level (TNL) in the presence of an 85 dB SPL continuous discourse passage. The test conditions included an unaided condition and an aided condition with combinations of NR and microphone modes within the UNIQUE hearing aid (omnidirectional microphone, no NR; omnidirectional microphone, NR; directional microphone, no NR; and directional microphone, NR) and the DREAM hearing aid (omnidirectional microphone, no NR; omnidirectional microphone, NR). Each tracking trial lasted 2 min for each hearing aid condition. Normal-hearing listeners tracked in the unaided condition only. Nine of the 13 hearing-impaired listeners returned after 3 mo for retesting in the unaided and aided conditions with the UNIQUE hearing aid. The individual TNL was estimated for each participant for all test conditions. The TNT index was calculated as the difference between 85 dB SPL and the TNL. RESULTS: The TNT index varied from 2.2 dB in the omnidirectional microphone, no NR condition to -4.4 dB in the directional microphone, NR on condition. Normal-hearing listeners reported a TNT index of -5.7 dB using this procedure. The averaged improvement in TNT offered by the NR algorithm on the UNIQUE varied from 2.1 dB when used with a directional microphone to 3.0 dB when used with the omnidirectional microphone. The time course of the NR algorithm was different between the UNIQUE and the DREAM hearing aids, with the UNIQUE reaching a stable TNL sooner than the DREAM. The averaged improvement in TNT index from the UNIQUE directional microphone was 3.6 dB when NR was activated and 4.4 dB when NR was deactivated. Together, directional microphone and NR resulted in a total TNT improvement of 6.5 dB. The test-retest reliability of the procedure was high, with an intrasession 95% confidence interval (CI) of 2.2 dB and an intersession 95% CI of 4.2 dB. CONCLUSIONS: The effect of the NR and directional microphone algorithms was measured to be 2-3 and 3.6-4.4 dB, respectively, using the TNT procedure. Because of its tracking property and reliability, this procedure may hold promise in differentiating among some hearing aid features that also differ in their time course of action.

Effects of cisplatin on the auditory function of ovariectomized rats with estrogen deficiency.

CONCLUSION: The ovariectomy in rats does not change their auditory function. However, combining ovariectomy with Cisplatin treatment increases the risk of damaging the auditory function relative to the ototoxic effect caused by Cisplatin alone or ovariectomy alone. OBJECTIVES: The auditory benefit from estrogen depends on a number of factors that make findings among studies controversial. The present study was to examine the impact of Cisplatin, a chemotherapy drug, on the auditory function of ovariectomized rats. METHODS: Thirty-two female rats were assigned to three groups (OVX + C, OVX - C, Sham + C). The rats in the OVX + C and OVX - C groups received bilateral ovariectomy, and those in the Sham + C group received a sham surgery with intact ovaries. After 6 weeks the rats in the OVX + C and Sham + C groups were then treated with Cisplatin for 4 days, but not those in the OVX - C group (control). The auditory function was measured with DPOAE SNRs and ABR thresholds before the surgery and after the Cisplatin treatment. RESULTS: The OVX + C group had significantly decreased the DPOAE SNRs and increased the ABR thresholds relative to the Sham + C group at stimulus frequencies between 2-8 kHz, and the Sham + C group also had worse auditory function than the OVX - C group.

Effects of Noise Exposure on the Auditory Function of Ovariectomized Rats with Estrogen Deficiency.

OBJECTIVE: The benefits of estrogen for the auditory function of women depend on a number of factors. In this study, we aimed to examine the impact of noise trauma on the auditory function of ovariectomized rats with estrogen deficiency. MATERIALS AND METHODS: Twenty-eight young, female Sprague-Dawley rats were assigned to three groups (OVX+N, OVX-N, Sham+N). Rats in the OVX+N group and the OVX-N group underwent bilateral ovariectomy (OVX); the OVX+N group alone was also exposed to white noise (N) of 115 dB SPL for 8 hours a day over 14 days. The Sham+N group consisted of rats with intact ovaries that were exposed to the same noise. The auditory function of all rats was measured before treatment and after noise exposure by the signal-to-noise ratio (SNR) of distortion-product otoacoustic emissions (DPOAE) and the threshold of auditory-evoked brainstem response (ABR). RESULTS: The Sham+N group (intact ovaries, noise-exposed) had worse auditory function than the OVX-N group (ovariectomy, no noise). The OVX+N group had decreased SNRs of DPOAE and increased ABR thresholds relative to the Sham+N group. CONCLUSION: Noise exposure may cause greater damage to auditory function when estrogen levels are low in females.

Speech intelligibility benefits of hearing AIDS at various input levels.

BACKGROUND: Although the benefits of hearing aids are generally recognized for soft- and conversational-level sounds, most studies have reported negative benefits (i.e., poorer aided than unaided performance) at high noise inputs. Advances in digital signal processing such as compression, noise reduction, and directional microphone could improve speech perception at high input levels. This could alter our view on the efficacy of hearing aids in loud, noisy situations. PURPOSE: The current study compared the aided versus the unaided speech intelligibility performance of hearing-impaired (HI) listeners at various input levels (from 50-100 dB SPL) and signal-to-noise ratios (SNRs; quiet, +6, +3, and -3 dB) in order to document the benefits of modern hearing aids. In addition, subjective preference between aided and unaided sounds (speech and music) at various input levels was also compared. RESEARCH DESIGN: The experiment used a factorial repeated-measures design. STUDY SAMPLE: A total of 10 HI adults with symmetrical moderate to severe hearing losses served as test participants. In addition, speech intelligibility scores of five normal-hearing (NH) listeners were also measured for comparison. INTERVENTION: Speech perception was studied at 50 and 65 dB SPL input levels in quiet and also in noise at levels of 65, 85, and 100 dB SPL with SNRs of +6, +3, and -3 dB. This was done for all participants (HI and NH). In addition, the HI participants compared subjective preference between the aided and unaided presentations of speech and music stimuli at 50, 65, 85, and 100 dB SPL in quiet. DATA COLLECTION AND ANALYSIS: The data were analyzed with repeated-measures analysis of variance. RESULTS: The results showed a decrease in aided benefits as input levels increased. However, even at the two highest input levels (i.e., 85 and 100 dB SPL), aided speech scores were still higher than the unaided speech scores. Furthermore, NH listeners and HI listeners in the aided condition showed stable speech-in-noise performance between 65 and 100 dB SPL input levels, except that the absolute performance of the NH listeners was higher than that of the HI listeners. Subjective preference for the unaided sounds versus the aided sounds increased as input level increased, with a crossover intensity at approximately 75 dB SPL for speech and 80 dB SPL for music. CONCLUSIONS: The results supported the hypothesis that the study hearing aid can provide aided speech-in-noise benefit at very high noise inputs in a controlled environment.

Amplification for listeners with a moderately severe high-frequency hearing loss.

BACKGROUND: Some evidence exists to support the use of an extended bandwidth (EBW) for those with a relatively mild to moderate degree of hearing loss. The use of frequency lowering is suggested for those with a severe/profound degree of hearing loss. The amplification option for those with a moderately severe hearing loss in the high frequencies is less clear. This study compared three amplification options for listeners with a moderately severe hearing loss in the high frequencies. PURPOSE: The efficacy of three amplification options-limited bandwidth to 4000 Hz, EBW, and frequency transposition-were evaluated for listeners with a moderately severe, high-frequency hearing loss. RESEARCH DESIGN: The experiment used a factorial repeated-measures design. STUDY SAMPLE: A total of 13 adults with bilateral hearing loss of 50-70 dB HL at 4000 Hz served as test participants. DATA COLLECTION AND ANALYSIS: The participants rated the sound quality of birdsongs and music when aided with the amplification options. Speech perception in quiet was measured at 50 dB SPL and 68 dB SPL input levels. The participants also completed a questionnaire on the best amplification option to use in different real-life environments during a 2 wk, take-home trial. The data were analyzed with repeated-measures analysis of variance. RESULTS: The findings showed that more listeners preferred the EBW for home use but that the frequency transposition was the least preferred. In addition, the performance of the EBW was better than that of the limited bandwidth in speech recognition but similar to that of the frequency transposition. CONCLUSIONS: The results supported the fitting of an EBW as the better choice for this group of listeners.

Development of the ORCA nonsense syllable test.

OBJECTIVES: Many new processing features in hearing aids have their primary effects on information located in the high frequencies. Speech perception tests that are optimized for evaluating high-frequency processing are needed to adequately study its effects on speech identification. The goal of the current research was to develop a medium for evaluating the effects of high-frequency processing in hearing aids. DESIGN: A list of 115 consonant-vowel-consonant-vowel-consonant nonsense syllables with American English consonants in all word positions was created in an open-set phoneme identification format. The source material was spoken by a male and a female speaker. A custom computer program was developed for administration of the test and automatic analysis of the test results. Nine normal-hearing listeners were employed in the collection of the normative data. The test was presented to the listeners in quiet (at 68 dB SPL), in noise at five signal-to-noise ratios (SNRs; -10, -5, 0, 5, and 10), and in a low-pass filter condition with cutoff frequencies at 500, 1000, 1500, 2000, and 4000 Hz. The data were examined to evaluate the psychometric properties of the test for different phoneme positions and phoneme classes. In addition, a shortened version of the test was developed based on the data from normal-hearing listeners. The test-retest reliability was verified at 0 dB SNR. The full and shortened versions of the test were repeated in 10 hearing-impaired listeners at their most comfortable listening level in quiet and in noise at various SNRs. RESULTS: The availability of high-frequency output was verified with acoustic analysis. The performance intensity functions for both versions of the test (i.e., male and female speakers) showed expected monotonic growth with SNR and cutoff frequencies. High reliability was seen between test and retest identification scores in normal-hearing and hearing-impaired listeners. CONCLUSIONS: The current nonsense syllable test provided a reliable and efficient means for phoneme identification testing.

Subjective and objective evaluation of noise management algorithms.

PURPOSE: To measure the subjective and objective improvement of speech intelligibility in noise offered by a commercial hearing aid that uses a fully adaptive directional microphone and a noise reduction algorithm that optimizes the Speech Intelligibility Index (SII). RESEARCH DESIGN: Comparison of results on the Hearing in Noise Test (HINT) and the Acceptable Noise Level task (ANL). STUDY SAMPLE: Eighteen participants with varying configurations of sensorineural hearing loss. RESULTS: Both the directional microphone and the noise reduction algorithm improved the speech-in-noise performance of the participants. The benefits reported were higher for the directional microphone than the noise reduction algorithm. A moderate correlation was noted between the benefits measured on the HINT and the ANL for the directional microphone condition, the noise reduction condition, and the directional microphone plus noise reduction conditions. CONCLUSIONS: These results suggest that the directional microphone and the SII-based noise reduction algorithm may improve the SNR of the listening environments, and both the HINT and the ANL may be used to study their benefits.

Efficacy of linear frequency transposition on consonant identification in quiet and in noise.

BACKGROUND: Frequency transposition has gained renewed interest in recent years. This type of processing takes sounds in the unaidable high-frequency region and moves them to the lower frequency region. One concern is that the transposed sounds mask or distort the original low-frequency sounds and lead to a poorer performance. On the other hand, experience with transposition may allow the listeners to relearn the new auditory percepts and benefit from transposition. PURPOSE: The current study was designed to examine the effect of linear frequency transposition on consonant identification in quiet (50 dB SPL and 68 dB SPL) and in noise at three intervals--the initial fit, after one month of use (along with auditory training), and a further one month of use (without directed training) of transposition. RESEARCH DESIGN: A single-blind, factorial repeated-measures design was used to study the effect of test conditions (three) and hearing aid setting/time interval (four) on consonant identification. STUDY SAMPLE: Eight adults with a severe-to-profound high-frequency sensorineural hearing loss participated. INTERVENTION: Participants were fit with the Widex m4-m behind-the-ear hearing aids binaurally in the frequency transposition mode, and their speech scores were measured initially. They wore the hearing aids home for one month and were instructed to complete a self-paced "bottom-up" training regimen. They returned after the training, and their speech performance was measured. They wore the hearing aids home for another month, but they were not instructed to complete any auditory training. Their speech performance was again measured at the end of the two-month trial. DATA COLLECTION AND ANALYSIS: Consonant performance was measured with a nonsense syllable test (ORCA-NST) that was developed at this facility (Office of Research in Clinical Amplification [Widex]). The test conditions included testing in quiet at 50 dB SPL and 68 dB SPL, and at 68 dB SPL in noise (SNR [signal-to-noise ratio] = +5). The hearing aid conditions included no transposition at initial fit (V1), transposition at initial fit (V2), transposition at one month post-fit (V3), and transposition at 2 months post-fit (V4). Identification scores were analyzed for each individual phoneme and phonemic class. Repeated-measures ANOVA were conducted using SPSS software to examine significant differences. RESULTS: For all test conditions (50 dB SPL in quiet, 68 dB SPL in quiet, and 68 dB SPL in noise), a statistically significant difference (p < 0.05 level) was reached between the transposition condition measured at two months postfitting and the initial fitting (with and without transposition) for fricatives only. The difference between transposition and the no-transposition conditions at the 50 dB SPL condition was also significant for the initial and one-month intervals. Analysis of individual phonemes showed a decrease in the number of confusions and an increase in the number of correct identification over time. CONCLUSIONS: Linear frequency transposition improved fricative identification over time. Proper candidate selection with appropriate training is necessary to fully realize the potential benefit of this type of processing.

Comparison of vent effects between a solid earmold and a hollow earmold.

BACKGROUND: Hollow earmolds have become a popular type of earmold used in thin-tube, microsize hearing aid fittings. It is desirable for clinicians to be familiar with their characteristics and limitations. PURPOSE: This investigation compared the effects of vent diameter between a traditional solid earmold and a hollow earmold that is used in modern thin-tube hearing aid fittings. RESEARCH DESIGN: A single-blind, 2 x 4 factorial design was used. STUDY SAMPLE: Eight adults with a high-frequency hearing loss participated. INTERVENTION: Custom earmolds for use with thin-tube hearing aids were made for each participant. Two types of earmolds were made: a solid earmold with a traditional vent length and a hollow earmold where the thickness of the shell was the length of the vent. Vent diameters were 0, 1, 2, and 3 mm. DATA COLLECTION AND ANALYSIS: The vent effect was evaluated on real-ear aided response, real-ear occluded response during vocalization, subjective occlusion rating, insertion loss, and maximum available gain before feedback. Real-ear measurements were made with the Fonix 6500 probe-microphone real-ear system. Vocalizations from the participants were analyzed with a custom MATLAB program, and statistical analysis was conducted with SPSS software. RESULTS: A systematic vent effect was seen with each earmold type as the nominal vent diameter changed. For the same vent diameter, the vent effect seen with the hollow earmold was greater than that of the solid earmold. CONCLUSIONS: Because of the difference in vent length (and thus acoustic mass) between a solid and a hollow earmold, the effect of vent diameter in a hollow earmold is more pronounced than that seen in a solid earmold of the same nominal vent diameter. Thus, a smaller vent diameter will be needed in a hollow earmold than in a solid earmold to achieve similar vent effects.

Personal amplification for school-age children with auditory processing disorders.

BACKGROUND: Children with auditory processing disorders (APD) are described to have a signal-to-noise ratio (SNR) difficulty. Frequency-modulated (FM) systems have been reported to improve this situation. Yet the use of personal amplification that may be more portable has not been attempted. PURPOSE: To determine whether personal amplification would result in improvement in speech-in-noise performances (attentiveness and speech recognition) and daily functioning in children with diagnosed APD. In addition, the desired hearing aid features (such as required gain, directional microphone and noise reduction, and open-ear fitting) are examined. RESEARCH DESIGN: A single-blind, longitudinal descriptive study in which subjects served as their own control in various hearing aid conditions. STUDY SAMPLE: Fourteen normal hearing children who had a diagnosis of APD and who were between the ages of 7 and 11 participated. INTERVENTION: All subjects wore bilateral, mild-gain, behind-the-ear, wide dynamic range compression hearing aids fitted in an open-ear mode. Gain on the hearing aids was adjusted to provide approximately 10 dB of insertion gain for conversational input. Directional microphone and noise reduction were used on the hearing aids. Subjects wore the hearing aids home and were encouraged to use them as much as possible in their daily environments (school, home, and social activities). Subjects were seen four times: an initial visit where hearing aids were fitted, then visits at 2 weeks, 3 months, and 6 months after the initial fitting. The majority of the testing was completed during these final three visits. DATA COLLECTION AND ANALYSIS: The children were evaluated on the Northwestern University word-list (NU-6) and the Auditory Continuous Performance Test (ACPT) in noise at most visits. The hearing aids were evaluated in the omnidirectional microphone mode only, omnidirectional microphone with noise reduction (NR) mode, and directional microphone with NR mode. The children's parents and teachers were asked to complete the Children's Auditory Processing Performance Scale (CHAPS) questionnaire both before and at the end of the study. RESULTS: The results showed that the use of hearing aids in the omnidirectional microphone mode alone did not improve speech identification in noise over the unaided condition. However, the inclusion of the NR algorithm and directional microphones improved speech understanding in noise. Amplification reduced the number of errors on the ACPT and improved several areas on the CHAPS; however, the results were not statistically significant. CONCLUSIONS: The use of mild-gain, open-ear fitting hearing aids with a directional microphone and noise reduction algorithm may be attempted on some children with APD on a trial basis.

Performance of a fully adaptive directional microphone to signals presented from various azimuths.

The signal-to-noise ratio advantage of a directional microphone is achieved by reducing the sensitivity of the microphone to sounds from the sides and back. A fully adaptive directional microphone (one that automatically switches between an omnidirectional mode and various directional polar patterns) may allow the achievement of signal-to-noise (SNR) improvement with minimal loss on audibility to sounds that originate from the sides and back. To demonstrate such possibilities, this study compared the soundfield aided thresholds, speech in quiet at different input levels, and speech in noise performance of 17 hearing-impaired participants under three microphone modes (omnidirectional, fixed hypercardioid, and fully [or automatic] adaptive) as the stimuli were presented from 0 degrees to 180 degrees in 45 degrees intervals. The results showed a significant azimuth effect only with the fixed directional microphone. In quiet, the fully adaptive microphone performed similarly as the omnidirectional microphone at all frequencies, input levels, and azimuths. In noise, the fully adaptive microphone achieved similar SNR improvement as the fixed directional microphone. Clinical implications of the results of this study were discussed.

Real-world performance of a reverse-horn vent.

The present study compared differences in subjective and objective performance in completely-in-the-canal (CIC) hearing aids with conventional uniform 1.5 mm parallel vents and another with a reverse horn vent where the diameter increased from 1.5 mm on the lateral faceplate to 3 mm on the medial opening of the hearing aid. Nine hearing-impaired persons with a high-frequency hearing loss participated. The test battery included unaided in situ thresholds, amount of available gain before feedback, speech in quiet, speech in noise (HINT), subjective ratings of hollowness and tolerance, objective measures of the occlusion effect, and real-ear aided response. Results showed less available gain before feedback but less occlusion effect for subjective ratings and objective measures with the reverse horn vent. This type of vent design may be useful to increase the effective vent diameter of custom (including CIC) hearing aids.

Vent configurations on subjective and objective occlusion effect.

The current study reexamined the effect of vent diameters on objective and subjective occlusion effect (OE) while minimizing two possible sources of variability. Nine hearing-impaired participants with primarily a high-frequency hearing loss were evaluated. Laser shell-making technology was used to make ear inserts of completely-in-the-canal (CIC) hearing aids for the study. This was to minimize any potential slit leakage from the inserts. The vent dimensions were systematically altered during the study. Participants sustained /i/ for 5 sec, and the real-ear occluded response was measured with a custom-made program that performed frequency averaging to reduce response variability. Participants also repeated the phrase "Baby Jeannie is teeny tiny" and rated their own voice. The results showed a systematic change in the objective OE and subjective ratings of OE as the vent diameter was modified. Furthermore, a significant correlation was seen between subjective rating and objective occlusion effect.