An Evaluation of Barrier Efficacy and Cognitive Evaluation Theory as Predictors of Exercise Attendance

The purpose of this study was to evaluate the barrier efficacy and cognitive evaluation theory with regard to predicting exercise attendance. Participants consisted of 189 undergraduates attending not-for-credit fitness classes at a regional comprehensive university in the Midwest. A revised 17-item version of the Intrinsic Motivation Inventory was used to assess exercise enjoyment and the three components of self-determination theory (competence, autonomy, and relatedness). A modified version of the Self-Efficacy Scale was used to assess self-efficacy. Attendance was significantly correlated with competency and self-efficacy. Regression results revealed that class, relatedness, and competence accounted for a significant amount of variance in attendance. Future research should examine the effects of competence-enhancing strategies on exercise adherence.     

The effects of music preference and exercise intensity on psychological variables

The purpose of this study was to examine the effects of music preference and exercise intensity on exercise enjoyment, perceived exertion (RPE), and attentional focus. Participants were assigned to 1 of 3 music preference conditions (most preferred, least preferred, or no music) and walked/ran on a treadmill at 1 of 3 exercise intensities (low, moderate, or high) for 20 minutes. Measures of exercise enjoyment, RPE, and attentional focus (association, dissociation, distress) were taken. A 3 x 3 ANOVA on enjoyment revealed that when participants paid attention to the music, music accounted for roughly 5% of the variance in exercise enjoyment (p = .04). Results of a 3 (music) x 3 (intensity) repeated measures ANOVA on RPE showed a main effect of intensity (p < .001) but no main effect for music and no interaction effect. A 3 x 3 ANOVA on attentional focus revealed that those in the high intensity condition reported the greatest association (p < .001) and distress (p < .001). Although not significant, on average, participants in the most preferred music condition reported the highest levels of dissociation.     

Coherence measurements in hearing instruments, using different broad-band signals.

In this investigation the effect of different broad-band test signals on non-linear distortion in hearing instruments was examined using coherence measurements, and the interaction between different test signals and types of automatic signal processing is explored. It is concluded that the use of coherence measurements to quantify non-linear distortion in hearing instruments is only valid for instruments without automatic signal processing. This limitation arises because interaction between type of test signal and the automatic signal processing used causes system time-variations, which influences the measured coherence function in an uncontrollable way.     

Effect of signal-to-noise ratio on directional microphone benefit and preference

This study examined speech intelligibility and preferences for omnidirectional and directional microphone hearing aid processing across a range of signal-to-noise ratios (SNRs). A primary motivation for the study was to determine whether SNR might be used to represent distance between talker and listener in automatic directionality algorithms based on scene analysis. Participants were current hearing aid users who either had experience with omnidirectional microphone hearing aids only or with manually switchable omnidirectional/directional hearing aids. Using IEEE/Harvard sentences from a front loudspeaker and speech-shaped noise from three loudspeakers located behind and to the sides of the listener, the directional advantage (DA) was obtained at 11 SNRs ranging from -15 dB to +15 dB in 3 dB steps. Preferences for the two microphone modes at each of the 11 SNRs were also obtained using concatenated IEEE sentences presented in the speech-shaped noise. Results revealed that a DA was observed across a broad range of SNRs, although directional processing provided the greatest benefit within a narrower range of SNRs. Mean data suggested that microphone preferences were determined largely by the DA, such that the greater the benefit to speech intelligibility provided by the directional microphones, the more likely the listeners were to prefer that processing mode. However, inspection of the individual data revealed that highly predictive relationships did not exist for most individual participants. Few preferences for omnidirectional processing were observed. Overall, the results did not support the use of SNR to estimate the effects of distance between talker and listener in automatic directionality algorithms.     

The occlusion effect in unilateral versus bilateral hearing aids

The benefit of bilateral hearing aids is well documented, but many hearing-aid users still wear only one aid. It is plausible that the occlusion effect is part of the reason for some hearing-aid users not wearing both hearing aids. In this study we quantified the subjective occlusion effect by asking ten experienced users of bilateral hearing aids and a reference group of ten normal-hearing individuals to rate the naturalness of their own voice while reading a text sample aloud. The subjective occlusion effect was evaluated in the unilateral versus bilateral condition for a variety of vent designs in earmolds and in a custom hearing aid. The subjective occlusion effect was significantly higher for bilateral hearing aids with all vent designs with the exception of a non-occluding eartip option. The subjective occlusion effect was reduced with the more open vent designs in both the unilateral and bilateral conditions. Assuming that the occlusion effect is a barrier to bilateral hearing aid use, these results indicate that open-hearing-aid fittings can help promote the use of two aids.     

Acoustic feedback margin improvements in hearing instruments using a prototype DFS (digital feedback suppression) system.

The properties of a prototype DFS (digital feedback suppression) system have been investigated. 21 ears fitted with behind-the-ear (BTE) hearing instruments and hard acrylic ear-moulds and 4 ears fitted with vented in-the-ear (ITE) hearing instruments were selected for the investigation. Two ITE instruments with different venting were employed to one of the ears. Complex loop gain has been measured in an anechoic room, and from these measurements the improvements in acoustic feedback margin due to the DFS system have been determined. For the BTE group, median values of 13.1 and 10.0 dB of improvement were established for two sets of measurements introducing a 180 degrees phase shift in connection with the last set of measurements. For the ITE group, values from 9.8 to 16.1 dB and from 13.7 to 16.3 dB of improvement were observed for the normal and the 180 degrees phase shift conditions respectively. Beyond this the DFS system may improve the sound quality to some extent, because the amplitude distortion, caused by the external feedback signal, is almost completely eliminated.     

Xanthopsia treated with thiamine

A patient with a history of extensive alcohol abuse developed xanthopsia, ataxia, and mental changes. Thiamine was given in the dosage of 200 mg daily, and the xanthopsia disappeared rapidly followed by normalization of the other symptoms. Xanthopsia might be due to a thiamine deficiency.     

Acoustical feedback associated with the use of post aural hearing aids for profoundly deaf children

The feedback properties of 29 ears fitted with post aural hearing aids and hard acrylic earmoulds, have been investigated for a group of profoundly deaf children. Complex loop gain has been measured, and maximum hearing aid gain before instability has been calculated from the measurement results. Guidelines for prediction of maximum hearing loss, which can be managed, are stated, and a suitable hearing aid frequency response for profoundly deaf children is proposed. This response ensures that acoustical feedback above approximately 1 kHz does not limit the low frequency gain, which is assumed to be very important for the speech recognition.     

Preferred low- and high-frequency compression ratios among hearing aid users with moderately severe to profound hearing loss

This study aimed to determine the low- and high-frequency compression ratios of a fast-acting device that were preferred by people with moderately severe to profound hearing loss. Three compression ratios (1:1, 1.8:1, and 3:1) were combined in the low and high frequencies to produce nine schemes that were evaluated pair-wise for three weeks in the field using an adaptive procedure. The evaluation was performed by 21 experienced hearing aid users with a moderately severe to profound hearing loss. Diaries and an exit interview were used to monitor preferences. Generally, the subjects preferred lower compression ratios than are typically prescribed, especially in the low frequencies. Specifically, 11 subjects preferred linear amplification in the low frequencies, and 14 subjects preferred more compression in the high than in the low frequencies. Preferences could not be predicted from audiometric data, onset of loss, or past experience with amplification. The data suggest that clients with moderately severe to profound hearing loss should be fitted with low-frequency compression ratios in the range 1:1 to 2:1 and that fine-tuning is essential.     

Real-ear measurement verification for open, non-occluding hearing instruments

Real-ear measurements using the modified pressure method with concurrent (real-time) equalization can be inaccurate, when amplified sound leaks out of the ear canal and reaches the reference microphone. In such situations the reference microphone will detect an increased sound level and reduce the output of the loudspeaker to maintain the desired level. The risk of having errors due to leaks increases if digital feedback suppression (DFS) is used, thus achieving higher feedback-free gain levels. The following hypotheses were tested: a) using the concurrent equalization method for fitting hearing instruments with DFS may result in underestimated real-ear insertion gain (especially when using open fittings) and b) as the benefit of the DFS system increases, this error also increases. Real-ear measurements were carried out in twenty-one subjects using the modified pressure method with stored equalization as well as with concurrent equalization. The results of the study supports both hypotheses. As a consequence it is recommended to use a stored equalization method for real-ear measurements of hearing instruments with DFS and open fitting.