Effects of Increasing the Overall Level or Fitting Hearing Aids on Emotional Responses to Sounds.

Adults with hearing loss demonstrate a reduced range of emotional responses to nonspeech sounds compared to their peers with normal hearing. The purpose of this study was to evaluate two possible strategies for addressing the effects of hearing loss on emotional responses: (a) increasing overall level and (b) hearing aid use (with and without nonlinear frequency compression, NFC). Twenty-three adults (mean age = 65.5 years) with mild-to-severe sensorineural hearing loss and 17 adults (mean age = 56.2 years) with normal hearing participated. All adults provided ratings of valence and arousal without hearing aids in response to nonspeech sounds presented at a moderate and at a high level. Adults with hearing loss also provided ratings while using individually fitted study hearing aids with two settings (NFC-OFF or NFC-ON). Hearing loss and hearing aid use impacted ratings of valence but not arousal. Listeners with hearing loss rated pleasant sounds as less pleasant than their peers, confirming findings in the extant literature. For both groups, increasing the overall level resulted in lower ratings of valence. For listeners with hearing loss, the use of hearing aids (NFC-OFF) also resulted in lower ratings of valence but to a lesser extent than increasing the overall level. Activating NFC resulted in ratings that were similar to ratings without hearing aids (with a moderate presentation level) but did not improve ratings to match those from the listeners with normal hearing. These findings suggest that current interventions do not ameliorate the effects of hearing loss on emotional responses to sound.

Binaural spatial adaptation as a mechanism for asymmetric trading of interaural time and level differences.

A classic paradigm used to quantify the perceptual weighting of binaural spatial cues requires a listener to adjust the value of one cue, while the complementary cue is held constant. Adjustments are made until the auditory percept appears centered in the head, and the values of both cues are recorded as a trading relation (TR), most commonly in µs interaural time difference per dB interaural level difference. Interestingly, existing literature has shown that TRs differ according to the cue being adjusted. The current study investigated whether cue-specific adaptation, which might arise due to the continuous, alternating presentation of signals during adjustment tasks, could account for this poorly understood phenomenon. Three experiments measured TRs via adjustment and via lateralization of single targets in virtual reality (VR). Targets were 500 Hz pure tones preceded by silence or by adapting trains that held one of the cues constant. VR removed visual anchors and provided an intuitive response technique during lateralization. The pattern of results suggests that adaptation can account for cue-dependent TRs. In addition, VR seems to be a viable tool for psychophysical tasks.

A Potential Bias in Subjective Ratings of Mental Effort.

Purpose: Subjective reports of listening effort are frequently inconsistent with behavioral and physiological findings. A potential explanation is that participants unwittingly substitute an easier question when faced with a judgment that requires computationally expensive analysis (i.e., heuristic response strategies). The purpose of this study was to investigate whether participants substitute the question "How did I perform?" when asked "How much effort did that take?". Method: Participants completed 2 sets of online surveys containing a text-based, multiple-choice synonym task. Expected performance and mental effort were manipulated across sets in 4 experiments, using a visual masking technique shown to correlate with speech-reception-testing in noise. Experiment 1 was designed to yield stable accuracy and differing effort across sets. Experiment 2 elicited differing accuracy and stable effort. Experiments 3 and 4 manipulated accuracy and performance in opposite directions. Participants included 273 adults (aged 19-68 years, M = 38.4 years). Results: Experiment 1 revealed no influence of perceived performance on ratings of effort when accuracy was stable. Experiment 2 showed that ratings of effort differed inversely with ratings of performance (lower performance and increased effort). Experiments 3 and 4 also demonstrated that participants rated effort in a manner inversely related to performance, regardless of the effort inherent in the condition. Conclusions: Participants likely substitute an easier question when asked to rate the multidimensional construct of mental effort. The results presented here suggest that perceived performance can serve as a ready heuristic and may explain the dissociation between subjective measures of listening effort and behavioral and physiological measures.

Reverberation enhances onset dominance in sound localization.

Temporal variation in sensitivity to sound-localization cues was measured in anechoic conditions and in simulated reverberation using the temporal weighting function (TWF) paradigm [Stecker and Hafter (2002). J. Acoust. Soc. Am. 112, 1046-1057]. Listeners judged the locations of Gabor click trains (4 kHz center frequency, 5-ms interclick interval) presented from an array of loudspeakers spanning 360° azimuth. Targets ranged ±56.25° across trials. Individual clicks within each train varied by an additional ±11.25° to allow TWF calculation by multiple regression. In separate conditions, sounds were presented directly or in the presence of simulated reverberation: 13 orders of lateral reflection were computed for a 10 m × 10 m room ( RT60≊300 ms) and mapped to the appropriate locations in the loudspeaker array. Results reveal a marked increase in perceptual weight applied to the initial click in reverberation, along with a reduction in the impact of late-arriving sound. In a second experiment, target stimuli were preceded by trains of "conditioner" sounds with or without reverberation. Effects were modest and limited to the first few clicks in a train, suggesting that impacts of reverberant pre-exposure on localization may be limited to the processing of information from early reflections.

Neural mechanisms of mental fatigue elicited by sustained auditory processing.

Despite growing evidence that prolonged episodes of effortful listening can lead to mental fatigue, little work has been done to examine the patterns of brain activation associated with listening over time. In order to gain a better understanding of the nature of listening-related mental fatigue, this study characterized the effects of sustained auditory processing on brain activation in 19 adults with normal hearing. A 50-min, auditory choice paradigm served as the fatiguing task. Mental fatigue was quantified using subjective (self-report) and behavioral (response time and accuracy) measures, as well as event-related potential (ERP) measures indexing motivation (error-related negativity; ERN) and general arousal (N1). Additional electrical neuroimaging analyses were carried out on ERP datasets. Subjective and behavioral results confirmed that participants became fatigued during the auditory task (data from the first 25min compared with the second 25min). ERPs revealed changes in neural activity consistent with decreased arousal (reduced N1 amplitude). Topographical analyses indicated decreased brain activation, without a change in underlying neural network configuration. Regions of decreased brain activation, as estimated via electrical neuroimaging, suggested a decrease in attention to task stimulus-response characteristics (reduced activation in regions associated with the dorsal attention network). The decrease in mean N1 amplitude revealed a significant, positive correlation with subjective report of reduced motivation. These findings support existing cognitive and neurophysiological models that suggest mental fatigue builds over time on task, and affects motivation to influence task performance. Furthermore, this study shows sustained auditory processing can elicit mental fatigue, and that dorsal parietal activity might provide a useful method of measuring its effects.

The Effects of Directional Processing on Objective and Subjective Listening Effort.

Purpose: The purposes of this investigation were (a) to evaluate the effects of hearing aid directional processing on subjective and objective listening effort and (b) to investigate the potential relationships between subjective and objective measures of effort. Method: Sixteen adults with mild to severe hearing loss were tested with study hearing aids programmed with 3 settings: omnidirectional, fixed directional, and bilateral beamformer. A dual-task paradigm and subjective ratings were used to assess objective and subjective listening effort, respectively, in 2 signal-to-noise ratios. Testing occurred in rooms with either low or moderate reverberation. Results: Directional processing improved subjective and objective listening effort, although benefit for objective effort was found only in moderate reverberation. Subjective reports of work and tiredness were more highly correlated with word recognition performance than objective listening effort. However, subjective ratings about control were significantly correlated with objective listening effort. Conclusions: Directional microphone technology in hearing aids has the potential to improve listening effort in moderately reverberant environments. In addition, subjective questions that probe a listener's desire to exercise control may be a viable method for eliciting ratings that are significantly related to objective listening effort.

Estimates of cochlear compression using distortion product otoacoustic emissions and growth of forward masking.

OBJECTIVE: The authors investigated the relationship between behavioral and physiologic estimates of cochlear compression. DESIGN: Cochlear compression was estimated in distortion product otoacoustic emission (DPOAE) fine structure minima and maxima near 4 kHz. The composite DPOAE response and separated generator and reflection components yielded three estimates in four young adults with normal hearing. DPOAE estimates were compared to behavioral compression estimates derived using a growth of forward masking (GOFM) paradigm. The DPOAE primary tone f2 and GOFM signal were identical and selected individually based on placement in a DPOAE fine structure minimum. RESULTS: Across participants, DPOAE compression estimates derived from the generator component were most similar to estimates derived from the GOFM paradigm and did not vary with DPOAE fine structure. CONCLUSIONS: These results suggest that the generator component may provide a quick, reliable estimate of cochlear compression in humans. This may prove useful in populations that cannot give behavioral responses.