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Stimulus context and absolute magnitude estimation: a study of individual differences.

The effect of stimulus context on absolute-magnitude-estimation (AME) judgments was examined by determining whether the loudness judgment of a tone is influenced by the intensities of other tones presented within the session. A group of 18 subjects was tested in separate sessions in which they judged stimuli within either a low (10-60 dB SL) or a high (40-90 dB SL) range of intensities. Examination of the results of individual subjects revealed that judgments of stimuli common to the two ranges were, in most subjects, unaffected or only slightly affected by the position of the range. The judgments of 2 subjects who failed to follow the instructions, however, showed very large context effects due to changing the stimulus range. The results of a second experiment, in which 22 subjects judged the loudness of tones within either a narrow (35-65 dB SL) or a wide (20-80 dB SL) range, revealed that, in all but 1 subject, the width of the range had no systematic effect on the loudness judgments of stimuli common to both ranges. This was also true 1 month later when 16 of the subjects returned to the laboratory to judge the loudness of tones within an even wider range of 10-90 dB SL. It was concluded that AME judgments are relatively insensitive to the potential biasing influences of stimulus context.

Adult↗

Auditory temporal summation in infants and adults: effects of stimulus bandwidth and masking noise.

A visually reinforced operant procedure was employed to determine the behavioral thresholds of 6- to 7-month-old infants and adults for stimuli of various bandwidths and durations. Experiment 1 compared absolute thresholds for broadband and 1/3-octave filtered clicks and 300-msec noise bursts. For adult subjects, the difference in threshold for clicks and noise bursts was quite comparable in the two bandwidth conditions, but infants' click-noise threshold differences were significantly larger for broadband than for 1/3-octave stimuli. In Experiment 2, 2-point threshold-duration functions were compared for 4-kHz tones and octave-band noise bursts presented in backgrounds of quiet and continuous noise. Infants' threshold-duration function for octave-band noise bursts was significantly steeper than the comparable adult function in quiet, but not in masking noise. These results suggest that young infants may have particular difficulty detecting low-intensity broadband sounds when durations are very short.

Adult↗

Optional processes in similarity judgments.

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configural dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identified before mandatory processes can be understood.

Adult↗

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 use 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.

Adult↗

Estimation of psychometric functions from adaptive tracking procedures.

Because adaptive tracking procedures are designed to avoid stimulus levels far from a target threshold value, the psychometric function constructed from the trial-by-trial data in the track may be accurate near the target level but a poor reflection of performance at levels far removed from the target. A series of computer simulations was undertaken to assess the reliability and accuracy of psychometric functions generated from data collected in up-down adaptive tracking procedures. Estimates of psychometric function slopes were obtained from trial-by-trial data in simulated adaptive tracks and compared with the true characteristics of the functions used to generate the tracks. Simulations were carried out for three psychophysical procedures and two target performance levels, with tracks generated by psychometric functions with three different slopes. The functions reconstructed from the tracking data were, for the most part, accurate reflections of the true generating functions when at least 200 trials were included in the tracks. However, for 50- and 100-trial tracks, slope estimates were biased high for all simulated experimental conditions. Correction factors for slope estimates from these tracks are presented. There was no difference in the accuracy and reliability of slope estimation due to target level for the adaptive track, and only minor differences due to psychophysical procedure. It is recommended that, if both threshold and slope of psychometric functions are to be estimated from the trial-by-trial tracking data, at least 100 trials should be included in the tracks, and a three- or four-alternative forced-choice procedure should be used. However, good estimates can also be obtained using the two-alternative forced-choice procedure or less than 100 trials if appropriate corrections for bias are applied.

Attention↗

Intensity resolution and subjective magnitude in psychophysical scaling.

Several successful theories of psychophysical judgment imply that exponents of power functions in scaling tasks should covary with measures of intensity resolution such as d' in the same tasks, whereas the prevailing metatheory of ideal psychophysical scaling asserts the independence of the two. In a direct test of this relationship, three prominent psychophysical scaling paradigms were studied: category judgment without an identification function, absolute magnitude estimation, and cross-modality matching with light intensity as the response continuum. Separate groups of subjects for each scaling paradigm made repeated judgments of the loudnesses of the pure tones that constituted each of two stimulus ensembles. The narrow- and wide-range ensembles shared six identical stimulus intensities in the middle of each set. Intensity resolution, as measured by d'-like distances, of these physically identical stimuli was significantly worse for the wide-range set for all three methods. Exponents of power functions fitted to geometric mean responses, and in magnitude estimation and cross-modality matching the geometric mean responses themselves, were also significantly smaller in the wide-range condition. The variation of power function exponents, and of psychophysical scale values, for stimulus intensities that were identical in the two stimulus sets with the intensities of other members of the ensembles is inconsistent with the metatheory on which modern psychophysical scaling practice is based, although it is consistent with other useful approaches to measurement of psychological magnitudes.

Adult↗

Range effects of an irrelevant dimension on classification.

In univariate classification tasks, subjects sort stimuli on the basis of the only attribute that varies. In orthogonal classification tasks, often called filtering tasks, there additionally are trial-to-trial variations in irrelevant attributes that the subjects are instructed to ignore. Performance is generally slower in filtering tasks than in univariate control tasks. We investigated this slowing in experiments of how the range of irrelevant trial-to-trial variation affects responses in pitch/loudness classification tasks. Using two levels of pitch and of loudness as stimuli, Experiment 1 replicated prior work showing that responses are slowed more when the range of the irrelevant dimension is made larger. Also in Experiment 1, sequential analyses showed that response time depends both on sequence and on the stimulus set independent of sequence. Experiments 2 and 3 used several levels on the irrelevant dimension and showed that responses to categorize loudness are slowed more by larger trial-to-trial pitch differences, but only on trials when the response repeats. When the response changes, performance is essentially unaffected by trial-to-trial irrelevant variation. This interaction supports the conclusion that slowed average performance in orthogonal classification tasks, which is known as Garner interference, is not due to difficulties that subjects have in filtering stimulus attributes. It is due to how subjects process successive stimulus differences. We call for more frequent reports of sequential analyses, because these can reveal information that is not available from data averages.

Adult↗

Impression of smoothness of a sound stream in relation to legato in musical performance.

Physically continuous sounds do not always produce the subjective impression of legato. In the present study, the effect of temporal factors on the impression of smoothness of a sound stream was systematically investigated in relation to the dynamic characteristics of hearing. The results showed that decaying sounds, successively presented, were perceived as being marginally connected when the sounds physically overlapped, while steady-state sounds were perceived as being marginally connected when they were physically separated. It was also shown that judgments by the subjects agreed quite well with the effect intended by the pianist when the passage was given in different temporal interpretations.

Adolescent↗

Brighter noise: sensory enhancement of perceived loudness by concurrent visual stimulation.

Two experiments investigated the effect of concurrently presented light on the perceived loudness of a low-level burst of white noise. The results suggest two points. First, white noise presented with light tends to be rated as louder than noise presented alone. Second, the enhancement in loudness judgments is resistant to two experimental manipulations: varying the probability that light accompanies sound and shifting from a rating method to a forced choice comparison. Both manipulations were previously shown to eliminate a complementary noise-induced enhancement in ratings of brightness. Whereas noise-induced enhancement of brightness seems to reflect a late-stage decisional process, such as a response bias, the present results suggest that light-induced enhancement of loudness may reflect an early-stage sensory interaction.

Adult↗

Speech recognition abilities of adults using cochlear implants with FM systems.

Speech recognition was evaluated for ten adults with normal hearing and eight adults with Nucleus cochlear implants (CIs) at several different signal-to-noise ratios (SNRs) and with three frequency modulated (FM) system arrangements: desktop, body worn, and miniature direct connect. Participants were asked to repeat Hearing in Noise Test (HINT) sentences presented with speech noise in a classroom setting and percent correct word repetition was determined. Performance was evaluated for both normal-hearing and CI participants with the desktop soundfield system. In addition, speech recognition for the CI participants was evaluated using two FM systems electrically coupled to their speech processors. When comparing the desktop sound field and the No-FM condition, only the listeners with normal hearing made significant improvements in speech recognition in noise. When comparing the performance across the three FM conditions for the CI listeners, the two electrically coupled FM systems resulted in significantly greater improvements in speech recognition in noise relative to the desktop soundfield system.

Adult↗

Revisiting loudness measures in children using a computer method of cross-modality matching (CMM).

The test efficiency and reliability of loudness assessment using a computer-controlled method of cross-modality matching (CMM) between line length and loudness was investigated in children 4 to 12 years with normal hearing or mild to severe degrees of sensorineural hearing loss. Adult listeners with normal hearing served as a comparison group. Computer-generated visual and acoustic stimuli were used to derive individual loudness data. Children and adults with normal hearing presented with similar loudness functions, while children with sensorineural hearing loss had steeper functions than their normal-hearing counterparts. Retest data supported reliability of the CMM method with children within the current study and between previous studies performed with a similar, but manual, method. The computer CMM approach proved more time efficient than the manual one, halving the test time. The CMM loudness task in a computerized version may have potential in a research or clinical setting, in particular for individualizing hearing aid fittings with children.

Acoustic Stimulation↗

ABR and DPOAE indices of normal loudness in children and adults.

Loudness growth prediction using normal templates of loudness derived with ABR and DPOAE measures was investigated in 20 children 4 to 12 years and 20 adults with normal hearing. An ABR click latency-intensity function (LIF), ABR 2 kHz tone LIF, and DPOAE 2 kHz amplitude-intensity function (AIF) were recorded from each listener. A loudness-intensity function was also measured for each electrophysiologic stimulus. Children and adults exhibited similar intensity functions of ABR latency, DPOAE amplitude, and loudness. A statistically significant relationship was found between loudness and ABR latency and DPOAE amplitude. Loudness estimation equations derived with ABR latency and DPOAE amplitude accurately and reliably predicted the loudness-intensity functions of the listeners. Normative ABR and DPOAE templates of predicted loudness growth may have clinical application in site-of-lesion assessment or hearing aid fitting by distinguishing abnormal rates of loudness growth for individuals who cannot provide reliable behavioral measures.

Acoustic Impedance Tests↗

Estimates of loudness, loudness discomfort, and the auditory dynamic range: normative estimates, comparison of procedures, and test-retest reliability.

The purpose of this series of experiments was to establish normative reference values for absolute and relative judgements of loudness discomfort and for the auditory dynamic range (DR), and to evaluate intersubject variability and intra-subject test-retest reliability for the respective measures of loudness discomfort. To establish the normal auditory DR, audiometric thresholds and loudness discomfort levels (LDLs) were measured from a group of 59 normal-hearing adults without sound tolerance problems. The resulting estimates of the LDL and DR were on the order of 100 dB HL and 95 dB, respectively. A subset (n = 18) of this larger group participated in further studies in which loudness growth functions and the upper limit of the auditory DR were measured by categorical scaling judgments. The findings revealed no significant differences between the test methods for absolute (LDL) and relative (categorical scaling) judgements of loudness discomfort, intersubject variability, or intrasubject test-retest reliability, and suggest that the simple LDL estimate of loudness discomfort is an efficient and valid clinical measure for characterizing the "threshold of discomfort."

Adult↗

Fitting hearing aids using clinical measures of loudness discomfort levels: an evidence-based review of effectiveness.

Clinical measurement of the loudness discomfort level (LDL) historically has been part of the hearing aid fitting procedure, and this clinical practice remains popular today. LDL measurements also are recommended in contemporary hearing aid fitting protocols. Yet, surveys show that many hearing aid users are dissatisfied with the loudness of their hearing aids. In this evidence-based review article, we evaluate the effectiveness of clinical LDL measurements. Specifically, we asked the question "Are the clinical measurements of LDL for adult patients predictive of aided acceptance and satisfaction of loudness for high inputs in the real world?" Nearly 200 articles were reviewed; three met the criteria set forth in this review. The evidence supported using unaided LDLs for selecting the maximum real-ear output of hearing aids. No study using aided LDLs or aided loudness verification met the criteria. The level of the evidence for the three articles using unaided LDLs was low; no higher than Level 4. The limited number of studies, the level of evidence, and the statistical power of the studies prevents us from making a strong recommendation concerning the clinical use of LDL measures. Additional research in this area, especially research employing randomized controlled trials would be a useful addition to this body of literature.

Hearing Aids↗

Effect of ear canal occlusion on pure-tone threshold sensitivity.

This study sought to quantify the effects of varying the degree of ear canal occlusion on pure-tone threshold sensitivity. Thresholds were obtained from each ear of five normal-hearing adults without occlusion, with complete occlusion, and with partial occlusion estimated to be 40-60% and 60-80%. A commercial lubricant was used in the completely occluded condition to eliminate possible acoustic leakage. Results showed a reduction of threshold sensitivity in all occluded conditions, with the greatest effect in frequencies above 1000 Hz. Only in the completely occluded condition were frequencies below 1000 Hz affected. In the partially occluded conditions, thresholds decreased by an average 7.5 dB and 13.0 dB across frequency for the 40-60% and 60-80% conditions respectively. At frequencies above 1000 Hz, the average threshold shifts for the two partially occluded conditions were 10.0 dB and 16.8 dB respectively. The implications of these findings on routine pure-tone audiometric procedures, with specific relevance for industrial hearing conservation programs, are discussed.

Acoustic Stimulation↗

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.

Acoustic Stimulation↗

Effect of multichannel digital signal processing on loudness comfort, sentence recognition, and sound quality.

This study evaluated the effect of increasing the number of processing channels from 32- to 64-signal processing channels on subjects' loudness comfort and satisfaction, sentence recognition, and sound quality of his or her own voice. Ten experienced hearing aid users with mild-to-moderate sensorineural hearing loss wore behind-the-ear (BTE) hearing aids with Adaptive Dynamic Range Optimization (ADRO) signal processing for a period of six weeks in the 32-channel and 64-channel conditions. Results revealed no significant differences in loudness comfort or satisfaction for the majority of sound samples as measured by the Subjective Loudness Test and Environmental Sounds Questionnaire. No significant differences in sentence recognition between the two processing conditions were found as measured by the Hearing In Noise Test (HINT). Additionally, no subjective differences in sound quality of subjects' own voice were determined by the Listening Tasks Questionnaire.

Aged↗