Relationship between loudness tolerance and the acceptance of background noise for young adults with normal hearing

This study investigated the relationship between listener loudness tolerance and listener acceptable noise level (ANL). Twenty-five normal hearing adults completed loudness tolerance and acceptable noise level measures. Loudness tolerance was measured using a scaling technique. The acceptable noise levels were calculated from a procedure designed to quantify a listener's willingness to accept background noise while listening to speech. Pearson correlation confirmed that loudness tolerance and acceptable noise levels are not related.     

Reduction of unique noise in the psychophysics of hearing by Group Operating Characteristic analysis

Group Operating Characteristic (GOC) analysis can be used to reduce the effects of unique noise on data from psychophysical experiments on hearing. Unique noise can come from physiological sources such as heartbeat and breathing and from other internal sources such as criterion variability, inattention, and faulty memory. The theory of GOC analysis is described and applied to the results of frequency discrimination experiments with human, pigeon, and simulated observers. The method yields relatively unattenuated measures of sensitivity, recovers Receiver Operating Characteristic curves from noisy choice data, and estimates the relative magnitudes of unique and common noise.     

Cognition and hearing aids

The perceptual information transmitted from a damaged cochlea to the brain is more poorly specified than information from an intact cochlea and requires more processing in working memory before language content can be decoded. In addition to making sounds audible, current hearing aids include several technologies that are intended to facilitate language understanding for persons with hearing impairment in challenging listening situations. These include directional microphones, noise reduction, and fast-acting amplitude compression systems. However, the processed signal itself may challenge listening to the extent that with specific types of technology, and in certain listening situations, individual differences in cognitive processing resources may determine listening success. Here, current and developing digital hearing aid signal processing schemes are reviewed in the light of individual working memory (WM) differences. It is argued that signal processing designed to improve speech understanding may have both positive and negative consequences, and that these may depend on individual WM capacity.     

Cognition and aided speech recognition in noise: Specific role for cognitive factors following nine-week experience with adjusted compression settings in hearing aids

The working memory model for Ease of Language Understanding (ELU) proposes that language understanding under taxing conditions is related to explicit cognitive capacity. We refer to this as the mismatch hypothesis, since phonological representations based on the processing of speech under established conditions may not be accessed so readily when input conditions change and a match becomes problematic. Then, cognitive capacity requirements may differ from those used for processing speech hitherto. In the present study, we tested this hypothesis by investigating the relationship between aided speech recognition in noise and cognitive capacity in experienced hearing aid users when there was either a match or mismatch between processed speech input and established phonological representations. The settings in the existing digital hearing aids of the participants were adjusted to one of two different compression settings which processed the speech signal in qualitatively different ways ("fast" or "slow"). Testing took place after a 9-week period of experience with the new setting. Speech recognition was tested under different noise conditions and with match or mismatch (i.e. alternative compression setting) manipulations of the input signal. Individual cognitive capacity was measured using a reading span test and a letter monitoring test. Reading span, a reliable measure of explicit cognitive capacity, predicted speech recognition performance under mismatch conditions when processed input was incongruent with recently established phonological representations, due to the specific hearing aid setting. Cognitive measures were not main predictors of performance under match conditions. These findings are in line with the ELU model.     

Masking of tones by tones and of noise by noise

Using a two-alternative temporal forced-choice technique, two binaural detection experiments were performed. In the first, the detectability of a 250-Hz 128-msec tonal signal masked by a gated 70-dB SPL tone of the same frequency and duration was measured as a function of the level of the signal, the phase angle at which the signal was added to the masker, and the interaural phase difference of the signal. In the second experiment, the signal was a wideband (100-3,000 Hz) 128-msec Gaussian noise masked by a continuous Gaussian noise of the same bandwidth and coherent with the signal. The detectability of this noise signal was measured as a function of the same variables investigated in the first experiment. In both experiments detectability was found to follow a simple energy- or power-detection model when the interaural phase difference was 0 deg. When the interaural phase difference was 180 deg, the function relating the signal level required for a constant level of performance to the signal-masker phase angle is such that neither the Webster-Jeffress hypothesis nor Durlach’s E-C model accounts for the data. The data are reasonably well fit by a model proposed by Hafter and Carrier.     

Stress and open-office noise

Forty female clerical workers were randomly assigned to a control condition or to 3-hr exposure to low-intensity noise designed to simulate typical open-office noise levels. The simulated open-office noise elevated workers' urinary epinephrine levels, but not their norepinephrine or cortisol levels, and it produced behavioral aftereffects (fewer attempts at unsolvable puzzles) indicative of motivational deficits. Participants were also less likely to make ergonomic, postural adjustments in their computer work station while working under noisy, relative to quiet, conditions. Postural invariance is a risk factor for musculoskeletal disorder. Although participants in the noise condition perceived their work setting as significantly noisier than those working under quiet conditions did, the groups did not differ in perceived stress. Potential health consequences of long-term exposure to low-intensity office noise are discussed.     

Preference for consonance over dissonance by hearing newborns of deaf parents and of hearing parents

Behavioral preferences for consonance over dissonance were tested in hearing infants of deaf parents and in hearing infants of hearing parents when they were 2 days old. Using a modified visual-fixation-based, auditory-preference procedure, I found that both 2-day-old infants of deaf parents and those of hearing parents looked longer at a visual stimulus when looking produced the original version of a Mozart minuet as opposed to a version altered to contain many dissonant intervals. The relative magnitude of such preference did not significantly differ whether their parents were deaf or hearing. Infants prefer consonance over dissonance, and the preference is present from birth and is not dependent on any specific prenatal or early postnatal experience.     

Influences of current mood and noise sensitivity on judgments of noise annoyance

Noise annoyance is one of the most studied reactions to auditory events. Previous research has demonstrated that annoyance reactions may be mediated by individual characteristics such as personality, attitudes, and noise sensitivity (traits). Transient temporary states such as an individual's current mood have been studied to a lesser extent. The author studied annoyance reactions to an everyday noise in participants who either were slightly annoyed or in a neutral affective state. The results showed that current mood had an overall effect on judgments of annoyance and on a participant's preference for sound. In addition, a participant's current mood interacted with noise sensitivity. These results indicate that both individual noise sensitivity (traits) and transient moods (states) are important for human auditory perception and evaluation.     

Effects of glide slope,noise intensity,and noise duration on the extrapolation of FM glides through noise

Listeners are quite adept at maintaining integrated perceptual events in environments that are frequently noisy. Three experiments were conducted to assess the mechanisms by which listeners maintain continuity for upward sinusoidal glides that are interrupted by a period of broadband noise. The first two experiments used stimulus complexes consisting of three parts: prenoise glide, broadband noise interval, and postnoise glide. For a given prenoise glide and noise interval, the subject’s task was to adjust the onset frequency of a same-slope postnoise glide so that, together with the prenoise glide and noise, the complex sounded as “smooth and continuous as possible.” The slope of the glides (1.67, 3.33, 5, and 6.67 Bark/sec) as well as the duration (50, 200, and 350 msec) and relative level of the interrupting noise (0, ?6, and ?12 dB S/N) were varied. For all but the shallowest glides, subjects consistently adjusted the offset portion of the glide to frequencies lower than predicted by accurate interpolation of the prenoise portion. Curiously, for the shallowest glides, subjects consistently selected postnoise glide onset-frequency values higher than predicted by accurate extrapolation of the prenoise glide. There was no effect of noise level on subjects’ adjustments in the first two experiments. The third experiment used a signal detection task to measure the phenomenal experience of continuity through the noise. Frequency glides were either present or absent during the noise for stimuli like those used in the first two experiments as well as for stimuli that had no prenoise or postnoise glides. Subjects were more likely to report the presence of glides in the noise when none occurred (false positives) when noise was shorter or of greater relative level and when glides were present adjacent to the noise.