Perceptual asymmetries associated with changing-loudness aftereffects

Listening to decreasing sound level leads to an increasing-loudness aftereffect, whereas listening to increasing sound level leads to a decreasing-loudness aftereffect. Measuring the aftereffects by nulling them in short test stimuli reveals that increasing-loudness aftereffects are greater than decreasing-loudness aftereffects. However, this perceptual asymmetry may be due to another illusion--the growing-louder effect: In the absence of any adaptation, short steady stimuli are heard as growing louder. In an experiment in which the duration of test stimuli varied from 1.0 to 2.5 sec, the growing-louder effect did not occur in the longer test stimuli, but the asymmetry in changing-loudness aftereffects remained. The aftereffect asymmetry is therefore independent of the growing-louder effect. The aftereffect asymmetry is consistent with other psychophysical and physiological evidence that is believed to concern potential collision: An approaching sound-source elicits increasing sound level. In addition, the aftereffect asymmetry parallels a well-known asymmetry regarding aftereffects of visual motion, which is also attributed to potential collision.     

The Spectrally Dependent Monotic Component in the Decreasing-Loudness Aftereffect: Implications for Dynamic Auditory Localization

Listeners exposed to a tone increasing in intensity report an aftereffect of decreasing loudness in a steady tone heard afterward. In the present study, the spectral dependence of the monotic decreasing-loudness aftereffect (adapting and testing 1 ear) was compared with (a) the spectral dependence of the interotic decreasing-loudness aftereffect (adapting 1 ear and testing the other ear) and (b) a non-adaptation control condition. The purpose was to test the hypothesis that the decreasing-loudness aftereffect may concern the sensory processing associated with dynamic localization. The hypothesis is based on two premises: (a) dynamic localization requires monaural sensory processing, and (b) sensory processing is reflected in spectral selectivity. Hence, the hypothesis would be supported if the monotic aftereffect were more spectrally dependent and stronger than the interotic aftereffect; A. H. Reinhardt-Rutland (1998) showed that the hypothesis is supported with regard to the related increasing-loudness aftereffect. Two listeners were exposed to a 1-kHz adapting stimulus. From responses of “growing softer” or “growing louder” to test stimuli changing in intensity, nulls were calculated; test carrier frequencies ranged from 0.5 kHz to 2 kHz. Confirming the hypothesis, the monotic aftereffect peaked at around the 1-kHz test carrier frequency. In contrast, the interotic aftereffect showed little evidence of spectrally dependent peaking. Except when test and adaptation carrier frequencies differed markedly, the interotic aftereffect was smaller than the monotic aftereffect.     

Relation of the verbal transformation and the phonemic restoration effects

This study examined the relationship between illusory changes of repeated words (“verbal transformations” or VTs) and illusory presence of phonemes replaced by noise (“phonemic restorations” or PhRs). Separate groups of 20 subjects were each presented with one of four taped variations of the repeated stimulus word “magistrate”: stimulus intact (MAGISTRATE); speech sound “s” removed and replaced with a silent gap (MAGI TRATE); speech sound “s” removed and replaced with a louder extraneous sound (MAGI¹TRATE); syllable “gis” removed and replaced with a louder extraneous sound (MA⁷¹TRATE). The stimuli MAGI¹TRATE and MA⁷¹TRATE evoked PhRs, and with these stimuli, the phonetic changes corresponding to VTs were concentrated at the perceptually restored portions of the word. It is suggested that both PhRs and VTs are related directly to perceptual processes employed normally for the correction of errors and resolution of ambiguities in speech. Other effects of PhRs upon VTs are described and implications of these findings for mechanisms underlying speech perception are discussed.     

The spectrally dependent monotic component in the decreasing-loudness aftereffect: implications for dynamic auditory localization

Listeners exposed to a tone increasing in intensity report an aftereffect of decreasing loudness in a steady tone heard afterward. In the present study, the spectral dependence of the monotic decreasing-loudness aftereffect (adapting and testing 1 ear) was compared with (a) the spectral dependence of the interotic decreasing-loudness aftereffect (adapting 1 ear and testing the other ear) and (b) a non-adaptation control condition. The purpose was to test the hypothesis that the decreasing-loudness aftereffect may concern the sensory processing associated with dynamic localization. The hypothesis is based on two premises: (a) dynamic localization requires monaural sensory processing, and (b) sensory processing is reflected in spectral selectivity. Hence, the hypothesis would be supported if the monotic aftereffect were more spectrally dependent and stronger than the interotic aftereffect; A. H. Reinhardt-Rutland (1998) showed that the hypothesis is supported with regard to the related increasing-loudness aftereffect. Two listeners were exposed to a 1-kHz adapting stimulus. From responses of "growing softer" or "growing louder" to test stimuli changing in intensity, nulls were calculated; test carrier frequencies ranged from 0.5 kHz to 2 kHz. Confirming the hypothesis, the monotic aftereffect peaked at around the 1-kHz test carrier frequency. In contrast, the interotic aftereffect showed little evidence of spectrally dependent peaking. Except when test and adaptation carrier frequencies differed markedly, the interotic aftereffect was smaller than the monotic aftereffect.     

The effects of sound duration on newborns' head orientation

Two experiments assessed the importance of sound duration for eliciting head orientation responses from newborn infants. In Experiment 1, thirty infants turned with equal frequency toward 20-s continuous rattle sounds and 20-s trains of rattle segments. The duration of the rattle segments--14 and 100 ms (2/s), or 500 ms (1/s)--did not influence the likelihood of turning. Response latencies and durations proved quite similar for all stimuli. In Experiment 2, twenty-four infants heard continuous rattle sounds of four different durations: 1, 5, 10, and 20 s. They turned reliably to all stimulus durations; furthermore, the magnitude and temporal characteristics of head orientation responses did not differ for the four stimulus durations. These results suggest that the newborn's head orientation response may reflect a motor program that is initiated by auditory input and then executed in a similar fashion regardless of further stimulation.     

The subjective duration of audiovisual looming and receding stimuli

Looming visual stimuli (log-increasing in proximal size over time) and auditory stimuli (of increasing sound intensity over time) have been shown to be perceived as longer than receding visual and auditory stimuli (i.e., looming stimuli reversed in time). Here, we investigated whether such asymmetry in subjective duration also occurs for audiovisual looming and receding stimuli, as well as for stationary stimuli (i.e., stimuli that do not change in size and/or intensity over time). Our results showed a great temporal asymmetry in audition but a null asymmetry in vision. In contrast, the asymmetry in audiovision was moderate, suggesting that multisensory percepts arise from the integration of unimodal percepts in a maximum-likelihood fashion.     

Integrating the irrelevant sound

A distractor can be integrated with a target response and the subsequent repetition of the distractor can facilitate or hamper responding depending on whether the same or a different response is required, a phenomenon labeled distractor-response binding. In two experiments we used a priming paradigm with an identification task to investigate influences of stimulus grouping on the binding of irrelevant stimuli (distractors) and responses in audition. In a grouped condition participants heard relevant and irrelevant sounds in one central location, whereas in a non-grouped condition the relevant sound was presented to one ear and the irrelevant sound was presented to the other ear. Distractor-based retrieval of the prime response was stronger for the grouped compared to the non-grouped presentation of stimuli indicating that binding of irrelevant auditory stimuli with responses is modulated by perceptual grouping.     

Working memory modulates the perception of time

Recent research has indicated that reentrant feedback from the contents of working memory can enhance neural representations and the perceptual strengths of matching stimuli in the visual field. However, whether the contents of working memory can also distort conscious experiences of perception remains unclear. Our present results show that the durations of perceptual stimuli matching the nontemporal representations in working memory tend to be perceived as longer than those of mismatching stimuli. This is the first demonstration that working memory can lead to distortions of time perception. Our findings are consistent with the ideas that the perceived duration of a stimulus depends on the magnitude of the neural responses to that stimulus in visual cortex and that there is a common system for representing both temporal and nontemporal magnitudes. We conclude that top-down modulation from the nontemporal contents of working memory distorts the perceptual experience of temporal duration.     

Conservation of temporal information by perceptual systems

Experiments in the auditory, visual, and vibratory modality employed two brief discriminably different stimuli, which were presented with temporal asynchronies unequivocally below the Hirsh-Sherrick threshold for performing temporal order judgments. A pair of such stimuli, experienced as a unitary perceptual event, is referred to as a “micropattern” composed of two “stimulus elements.” Ss could readily distinguish between two such micropatterns in which the temporal order of the stimulus elements was reversed. The discrimination was based on the perceptual dominance of the second stimulus element of each micropattern. This perceptual dominance was studied as a function of stimulus-element onset and offset asynchrony, the duration and intensity of the stimulus elements, and the difference (in frequency or wavelength) between the stimulus elements of a micropattern. The results suggest the existence of an operation of all perceptual systems in the time domain that acts to conserve information concerning the temporal order of the two stimulus elements at the expense of discriminatory acuity of the f’~rst element.     

Vibrotactile--auditory interactions are post-perceptual

Vibrotactile stimuli can elicit compelling auditory sensations, even when sound energy levels are minimal and undetectable. It has previously been shown that subjects judge auditory tones embedded in white noise to be louder when they are accompanied by a vibrotactile stimulus of the same frequency. A first experiment replicated this result at four different levels of auditory stimulation (no tone, tone at detection threshold, tone at 5 dB above threshold, and tone at 10 dB above threshold). The presence of a vibrotactile stimulus induced an increase in the perceived loudness of auditory tones at three of the four values in this range. In two further experiments, a 2-interval forced-choice procedure was used to assess the nature of this cross-modal interaction. Subjects were biased when vibrotaction was applied in one interval, but applying vibrotaction in both intervals produced performance comparable to conditions without vibrotactile stimuli. This demonstrates that vibrotaction is sometimes ignored when judging the presence of an auditory tone. Hence the interaction between vibrotaction and audition does not appear to occur at an early perceptual level.     

Auditory accessory effects on visual processing

A series of experiments on intersensory facilitation demonstrates that non-informative sound of low to moderate intensity (30/80 dB) facilitates the reaction to a visual stimulus. By manipulating the preprocessing and perceptual stages of the visual signals, it appears that auditory intensity reduces choice reaction time independently from the positive influence of the intensity and duration of the visual imperative signal, but interacts with the effect of stimulus degradation. Degraded stimuli take more profit of the sound than intact stimuli. Besides a short-term activation effect, originated by accessories of the auditory modality, on the motor adjustment stage (cf. Sanders 1983), the results suggest that the accessory influences the stage of feature extraction.     

The effects of speed and accuracy strategies in an information-reduction task

Developmental changes in the ability to make relational judgments of sound intensity were examined with 3-, 4-, and 5-year-old children. The hypothesis that correct judgments of “louder” precede correct judgments of “softer” was supported. The results were discussed with reference to the development of the understanding of logical relations as proposed by Piaget. The role of magnitude of perceptual information in the development of relational judgments also was discussed.     

Feature analyzers for the phonetic dimensionstop vs. continuant

Perception of sounds along the phonetic dimensionstop vs. continuant was studied by means of a selective adaptation procedure. Subjects first identified a series of synthetic consonant-vowel syllables whose formant transitions varied in duration, slope, and amplitude characteristics. They were perceived as either [ba] or [wa]. After the initial identification test, an adapting stimulus was presented repeatedly, and then the subjects again identified the original test series. Adapting with a stop (either [ba] or [da]) led to a decrease in the number of test stimuli identified as [ba], whereas adapting with the continuant sound [wa] led to an increase in the number of [ba] identification responses. Removing the vowel portion of an adapting stimulus greatly reduced the identification shift only when the resulting stimulus was no longer perceived as speech-like. A reduction in the number of [ba] identifications occurred even when a nonspeech “stop” (the sound of a plucked string) was used as the adapting stimulus, suggesting that phonetic processing is not a necessary condition for an adaptation effect.     

Informational and neural adaptation curves are asynchronous

Norwich’s entropy theory of perception (plus a few additional assumptions) suggests the existence of an “informational adaptation curve” (change in stimulus equivocation with stimulus duration) for suprathreshold prothetic stimuli that is synchronous with the “neural adaptation curve” (change in firing rate with stimulus duration) observed for sensory neurons. Five experiments are reported in which informational adaptation curves were measured for auditory and visual stimuli by having subjects make absolute identifications of suprathreshold sound or light intensities of various durations. Information transmissions for the shortest duration stimuli (1 and 5 msec, respectively, for light and sound) were surprisingly large (small equivocations), indicating that intensity information is acquired very rapidly by the whole organism. The equations of entropy theory were fitted to adaptation data for peripheral sensory neurons (spiral ganglion cells and retinal ganglion cells) and were compared to the informational adaptation curves. It was found that informational adaptation occurred more rapidly than neural adaptation. That is, the two types of adaptation process are asynchronous. However, for both audition and vision, the total amount of information mediated by the adaptation process (channel capacity) was-about the same for both types of processes (2.03 bits vs. 2.1 bits per stimulus for sound intensity; 1.3 vs. 2.0 bits per stimulus for light intensity). Faster acquisition could be accomplished in the whole organism through convergent neural circuits that increase sampling, rate-by pooling the samples taken by individual receptor systems     

Discrimination by newborns of the intensity, frequency and temporal characteristics of auditory stimuli

The ability of 3- to 5-day-old neonates to discriminate between auditory stimuli, in terms of each of the dimensions of intensity, pitch and time, was studied using heart-rate responses in a habituation paradigm. For each of the dimensions a survey of the literature failed to provide results which could be used as the basis for later work involving auditory patterns. Further analysis of an earlier experiment (Stratton, 1970 a) involving stimuli at 80, 85 and 90 db showed that louder stimuli evoked larger initial responses and more rapid habituation. From the same experiment it was found that a change of pitch produced dishabituation as early as the 10th trial. There are reasonable grounds for attributing the increased response to the frequency characteristics rather than a change in the perceived intensity of the stimuli. Previous experiments suggested that fixed inter-stimulus intervals tended to produce anticipatory heart-rate changes and modify the magnitude and latency of the response. Two experiments designed specifically to examine temporal phenomena revealed time-linked behaviour. In both experiments acceleratory responses occurred at the first stimulus omission of a fixed-interval series. Not all of the subjects showed this effect, and in both experiments, only the subjects who failed to respond to the first stimulus presentation responded to stimulus omission. The findings are discussed in relation to general issues of neonatal psychophysiology, and it is concluded that neonates can discriminate in each of the auditory dimensions, but that preliminary work involving patterns should concentrate on varying pitch and intensity.     

Note on aftereffect of unidirectional sound-level change with different durations of test stimulus

Prolonged listening to unidirectional change of sound level in a tone can cause a steady tone afterwards to change in apparent loudness in the opposite direction. Subjectively the present aftereffect appears strong immediately after removal of the adaptor, becoming much weaker within a second or so. To confirm this, the aftereffect was measured by nulling with different durations of test stimulus changing steadily in sound level. As predicted, rate of change of sound level was greater for the shorter test stimuli. This suggests that aftereffect measurement by nulling may be best achieved with short test stimuli. However, responses to shorter test stimuli were generally more scattered.     

A further study of melodic channeling

Subjects listened to repetitive presentations of C major scale patterns and simple two-part contrapuntal specimens, both dichotically and in a stereophonic free sound field. All scalar and melodic patterns were presented so that successive tones alternated from ear to ear: when a component of one scale or melody was routed through one speaker or headphone, the concurrent member of the other scale or melodic pattern was routed through the other speaker or headphone, and vice versa. The stimulus parameters of spectral contour and envelope characteristics, duration, melodic pattern, and loudness were varied, and a testing procedure was designed to minimize any bias in responses which might be produced by learning, immediate memory, or vocal Limitations of subjects. Virtually all responses (95.2% to scalar stimuli, 99.1% to melodic stimuli) indicated that the subjects channeled stimuli by pitch range, and not by ear of input. When spectral contours routed through the separate headphones or speakers were noticeably dissimilar, no subject perceived that this timbral inequality switched from ear to ear: all subjects heard an overall change in tone quality which pervaded both scalar or melodic sequences, and which apparently emanated from both headphones or speakers.     

Effect of stimulus duration on perceptual onset and offset latencies

The effects of stimulus duration on perceptual onset and offset latency were compared in vision and audition. It was found that perceptual onset latency was independent of stimulus duration but that the perceptual offset latency was longer for brief stimuli than for stimuli that exceeded a critical duration. For stimuli longer than the critical duration, the perceptual onset and offset latencies were equal: The same temporal relationships were found in both modalities. The results indicate that for any specific stimulus parameters, reduction of stimulus duration results, ultimately, in a perception of fixed duration.     

Perceptual order and the effect of vocalic context on fricative perception

This three-part study demonstrates that perceptual order can influence the integration of acoustic speech cues. In Experiment 1, the subjects labeled the [s] and [∫] in natural FV and VF syllables in which the frication was replaced with synthetic stimuli. Responses to these “hybrid” stimuli were influenced by cues in the vocalic segment as well as by the synthetic frication. However, the influence of the preceding vocalic cues was considerably weaker than was that of the following vocalic cues. Experiment 2 examined the acoustic bases for this asymmetry and consisted of analyses revealing that FV and VF syllables are similar in terms of the acoustic structures thought to underlie the vocalic context effects. Experiment 3 examined the perceptual bases for the asymmetry. A subset of the hybrid FV and VF stimuli were presented inreverse, such that the acoustic and perceptual bases for the asymmetry were pitted against each other in the listening task. The perceptual bases (i.e., the perceived order of the frication and vocalic cues) proved to be the determining factor. Current auditory processing models, such as backward recognition masking, preperceptual auditory storage, or models based on linguistic factors, do not adequately account for the observed asymmetries.     

汉语普通话母语者的节奏组块感知偏好

个体对声音节奏的感知具有明显的偏好,强度上表现为扬抑组块偏好,时长上表现为抑扬组块偏好,这被称作抑扬-扬抑规律,但这一感知规律是否具有跨语言的普遍性却存在争议。本研究以汉语普通话母语者为被试,考察他们对非语音音调序列的节奏组块感知情况,结果发现强度和时长参数下被试对扬抑形式的判断比例均显著高于随机水平,说明汉语普通话母语者在两个参数上的节奏感知中均表现出明显的扬抑偏好,在强度上支持节奏感知偏好具有跨语言普遍性的观点,在时长上不支持节奏感知偏好受到母语短语韵律特征影响的观点。