Temporal course of perceived auditory duration

A series of experiments explored the temporal course of the perceived duration of an auditory stimulus. A backward recognition masking paradigm was utilized, in which the subject was to determine which of two target durations was presented on a given trial. The target tone was followed, after a variable silent intertone interval, by a masking tone which could assume one of three possible durations. Identification of the long target was found to improve consistently with increases in the intertone interval. In contrast, identification of the short target was as accurate at the short as at the long intertone intervals. Blocking the intertone interval across experimental sessions eliminated these differences between the two target tones. Performance on both the long and the short target tones improved monotonically with increases in the intertone interval. When masking tone duration was randomized within an experimental session, identification of the long (short) target was most accurate with the longer (shorter) masking tone. Blocking the duration of the masking tone across experimental sessions eliminated the effect of the duration of the mask, but did not alter any of the other results. A model, proposed to account for the results, assumes that the percept of target duration grows over time, and can be terminated by the onset of the masking tone. The masking tone also acts to lengthen the perceived duration of the target tone, and this lengthening is a direct function of the duration of the masking tone.     

Some characteristics of auditory spatial attention revealed using rhythmic masking release

The tuning of auditory spatial attention with respect to interaural level and time difference cues (ILDs and ITDs) was explored using a rhythmic masking release (RMR) procedure. Listeners heard tone sequences defining one of two simple target rhythms, interleaved with arhythmic masking tones, presented over headphones. There were two conditions, which differed only in the ILD of the tones defining the target rhythm: For one condition, ILD was 0 dB and the perceived lateral position was central, and for the other, ILD was 4 dB and the perceived lateral position was to the right; target tone ITD was always zero. For the masking tones, ILD was fixed at 0 dB and ITDs were varied, giving rise to a range of lateral positions determined by ITD. The listeners' task was to attend to and identify the target rhythm. The data showed that target rhythm identification accuracy was low, indicating that maskers were effective, when target and masker shared spatial position, but not when they shared only ITD. A clear implication is that at least within the constraints of the RMR paradigm, overall spatial position, and not ITD, is the substrate for auditory spatial attention.     

Illusory conjunctions of pitch and duration in unfamiliar tone sequences

In 3 experiments, the authors examined short-term memory for pitch and duration in unfamiliar tone sequences. Participants were presented a target sequence consisting of 2 tones (Experiment 1) or 7 tones (Experiments 2 and 3) and then a probe tone. Participants indicated whether the probe tone matched 1 of the target tones in both pitch and duration. Error rates were relatively low if the probe tone matched 1 of the target tones or if it differed from target tones in pitch, duration, or both. Error rates were remarkably high, however, if the probe tone combined the pitch of 1 target tone with the duration of a different target tone. The results suggest that illusory conjunctions of these dimensions frequently occur. A mathematical model is presented that accounts for the relative contribution of pitch errors, duration errors, and illusory conjunctions of pitch and duration.     

Effects of context on auditory stream segregation

The authors examined the effect of preceding context on auditory stream segregation. Low tones (A), high tones (B), and silences (-) were presented in an ABA- pattern. Participants indicated whether they perceived 1 or 2 streams of tones. The A tone frequency was fixed, and the B tone was the same as the A tone or had 1 of 3 higher frequencies. Perception of 2 streams in the current trial increased with greater frequency separation between the A and B tones (Delta f). Larger Delta f in previous trials modified this pattern, causing less streaming in the current trial. This occurred even when listeners were asked to bias their perception toward hearing 1 stream or 2 streams. The effect of previous Delta f was not due to response bias because simply perceiving 2 streams in the previous trial did not cause less streaming in the current trial. Finally, the effect of previous ?f was diminished, though still present, when the silent duration between trials was increased to 5.76 s. The time course of this context effect on streaming implicates the involvement of auditory sensory memory or neural adaptation.     

Why are damped sounds perceived as shorter than ramped sounds?

Hearing is the most accurate sense for perceiving duration. However, rarely it produces inaccurate estimates of duration, for example when it compares the subjective duration of tones that are increasing in intensity over time (i.e., ramped) with that of tones that are decreasing in intensity over time (i.e., damped). The literature reports that the damped tones are perceived as much being shorter than the ramped tones of the same length. The short subjective duration of damped tones may originate from a decay suppression mechanism that parses the source-informative part of many natural sounds (i.e., the beginning) from the less informative part of them (the decay): listeners may interpret the tail of damped tones like an echo or like the decay portion of an impact sound and exclude it from the account of the duration of the tone. In the natural soundscape, the tail of sounds produced in reverberant environments and the tail of impact sounds have a frequency content that is constant throughout the sound’s duration. Here, the carriers used for ramped and damped sounds were a tone constant in frequency and a tone modulated in frequency. The frequency modulation was introduced to prevent the listener from interpreting the tail of these tones as the result of reverberation or the decay portion of an impact sound. Frequency constant damped tones were largely underestimated in duration whereas frequency modulated ones were not (or were only slightly), demonstrating that the decay suppression mechanism is a worthy explanation for the short subjective duration of damped tones.

     

Perceived duration as a function of pitch

It was demonstrated with 7 observers that the duration of a high frequency tone was perceived to be longer than the duration of a low frequency tone, even though the actual duration of the two tones was equal.     

Cross-octave masking of single tones and musical sequences: The effects of structure on auditory recognition

A series of experiments explored the role of structural information in the auditory recognition process, within the context of a backward recognition masking paradigm. A masking tone presented after a test tone has been found to interfere with the perceptual processing of the test tone, the degree of interference decreasing with increased durations of the silent intertone interval between the test and masking tones. In the current studies, the task was modified to utilize three-tone sequences as the test stimuli. Six test sequences were employed (LMH, LHM, MLH, MHL, HLM, HML), where L, M, and H represent the lowest, middle, and highest frequencies in the melody. The observers identified these six possible sequences when the three tones of the test sequence were interleaved with three presentations of a single masking tone. All three tones of the test sequence were drawn from the same octave, while the masking tones could be drawn from any of three octaves, symmetrical around the octave containing the test tones. Under these conditions, interference occurred primarily from masking tones drawn from the same octave as the test tones. Masking tones drawn from other octaves were found to produce little, if any, interference with perception of the test tones. This effect was found to occur only for the identification of tonal sequences. Substantial masking of single-tone targets occurred with masking tones drawn from octaves other than that containing the targets. The results make apparent the use of structural information during auditory recognition. A theoretical interpretation was advanced which suggests that, while single tones are perceived on the basis of absolute pitch, the presence of auditory structure may allow relational information, such as exact pitch intervals or melodic contour, to facilitate perception of the tonal sequence.     

Feature processing during high-rate auditory selective attention

Auditory event-related brain potentials (ERPs) and reaction times were, analyzed in a selective attention task in which subjects attended to tone pips presented at high rates-Xinterstimulua intervals [ISIs] of 40-200 msec). Subjects responded to infrequent target tones of a specified frequency (250 or 4000 Hz) and location (left or right ear) that were louder than otherwise identical tones presented randomly to the left and right ears. Negative difference (Nd) waves were isolated by subtracting ERPs to tones with no target features from ERPs to the same tones when they shared target location, frequency, or both frequency and location cues. Nd waves began 60-70 msec after tone onset and lasted until 252–350 msec after tone onset, even for tones with single attended cues. The duration of Nd waves exceeded the ISIs between successive tones, implying that several stimuli underwent concurrent analysis. Nd waves associated with frequency processing had scalp distributions different from those associated with location processing, implying that the features were analyzed in distinct cortical areas. Nd waves specific to auditory feature conjunction were isolated. These began at latencies of 110–120 msec, some 30-40 msec after the Nds to single features. The relative timing of the different Nd waves suggests that auditory feaure conjunction begins after a brief parallel analysis of individual features but before feature analysis is complete.     

Spatial extent and figural factors in backward masking

Spatial and figural characteristics of backward masking were studied, with two collinear arcs presented end-to-end and serving as target and mask, respectively. Stimulus onset asynchrony was 50 ms while interstimulus interval was 0 ms. Mask exposure duration required for masking was determined as a function of target length with mask length as a parameter. The exposure duration of the mask required for complete masking varied directly with target length, but inversely with mask length. The fact that masking strength increased with mask duration while all other parameters were kept constant suggests that masking depended on stimulus termination asynchrony. Maximal masking occurred for target arcs as long as 5.0 deg of visual angle, exceeding previously reported distances. Misaligned or differently shaped stimuli produced less masking, suggesting that figural factors play a role in long-range backward masking.     

A PRP-study to determine the locus of target priming effects

Visual stimuli that are made invisible by a following mask can nonetheless affect motor responses. To localize the origin of these target priming effects we used the psychological refractory period paradigm. Participants classified tones as high or low, and responded to the position of a visual target that was preceded by a prime. The stimulus onset asynchrony (SOA) between both tasks varied. In Experiment 1 the tone task was followed by the position task and SOA dependent target priming effects were observed. When the visual position task preceded the tone task in Experiment 2, with short SOA the priming effect propagated entirely to the tone task yielding faster responses to tones on visually congruent trials and delayed responses to tones on visually incongruent trials. Together, results suggest that target priming effects arise from processing before and at the level of the central bottleneck such as sensory analysis and response selection.     

视觉掩蔽可基于知觉到的客体位置

利用flash—lag效应分离视觉掩蔽中客体的物理位置和知觉位置,以探讨掩蔽效应是否基于知觉到的客体位置。实验中掩蔽刺激做圆周运动,到某一位置时,目标刺激短时呈现,要求被试判断目标刺激（缺角菱形）的缺角方向。通过操作目标呈现时二者之间的相对位置,发现当二者物理位置不重合而知觉位置重合时掩蔽效应最大。该结果表明,视觉掩蔽可基于知觉到的客体位置。     

Accents in equitone sequences

Equitone sequences are defined as sequences of tones that are identical in all respects: frequency, spectral composition, intensity, and duration. The only parameter varied in these sequences is the time-interval between tones. In such sequences, clear accents are perceived. This paper describes accent perception in equitone sequences containing two alternating intervals; such sequences are perceived as consisting of repeating groups of two tones. An accent is heard on the first tone of a group if the difference between the intervals is about 5% to 10%. If the difference is made bigger, the accent is heard on the last tone of the group; this latter accent is considerably stronger than the accent previously heard on the first tone. In a number of experiments, the conditions under which the two types of accents occur were investigated. From these experiments, it was tentatively concluded that the accent on the last tone is heard because that tone, since it is followed by a longer interval, can be processed more completely. This “intervalproduced” accent indeed occurs only if the between-group interval is considerably longer than the within-group interval and if the latter does not exceed a duration of about 250 msec. The effect is slightly dependent on tone duration. The interval-produced accent can be balanced if the nonaccented tone is increased by about 4 dB in intensity. This shows that the effect is quite robust. The specific type of accentuation reported here might explain some rhythmical phenomena, examples of which are given.     

Similarity effects in backward recognition masking

Auditory backward recognition masking refers to the ability of a masking sound to terminate further perceptual resolution of a test sound presented slightly earlier in time. The present experiments were conducted to determine whether mask/test tone similarity effects in backward recognition masking could be reliably demonstrated. Although similarity effects were found in Experiments 1 and 2, only about 60% of the subjects demonstrated these effects. Experiment 3 was designed to isolate which stage of information processing is responsible for similarity effects. It was hypothesized that similarity effects are due to mask interference with the synthesized auditory memory of the test tone rather than to selective overwriting of a preperceptual auditory store: previous research has shown that interference in synthesized auditory memory depends on the similarity of the interfering stimulus to the items held in memory. By independently varying the backward masking interval and the interfering effect of the mask on the test tone memory, it was possible to demonstrate that similarity effects are indeed caused by mask interference in synthesized memory. The implications of these results are considered in the framework of auditory and visual masking.     

The auditory continuity illusion: a parametric investigation and filter model

A sound that is briefly interrupted by a silent gap is perceived as discontinuous. However, when the gap is filled with noise, the sound may be perceived as continuing through the noise. It has been shown that this continuity illusion depends on the masking of the omitted target sound, but the underlying mechanisms have yet to be quantified thoroughly. In this article, we systematically quantify the relation between perceived continuity and the duration, relative power, or notch width of the interrupting broadband noise for interrupted and noninterrupted amplitude-modulated tones at different frequencies. We fitted the psychometric results in order to estimate the range of the noise parameters that induced auditory grouping. To explain our results within a common theoretical framework, we applied a power spectrum model to thedifferent masking resultsand estimated the critical bandwidth of the auditory filter that may be responsible for the continuity illusion. Our results set constraints on the spectral resolution of the mechanisms underlying the continuity illusion and provide a stimulus set that can be readily applied for neurophysiological studies of its neural correlates.     

Pure-tone perception and ear advantages in dichotic listening

A same-different matching task was used to investigate how subjects perceived a dichotic pair of pure tones. Pairs of stimulus tones in four frequency ranges (center frequencies of 400–1,700 Hz), with separations between 40 and 400 Hzt were tested. Five types of test tones were matched to the stimulus pair: the stimulus pair presented again (control) or crossed over (same tones, different ears), the geometric mean of the two tones, or a binaural tone of the low or high tone of the pair. In the lowest frequency range and the highest with maximum separation, the crossed-over test tones were perceived as different from the same stimulus tones. A bias for perceiving the higher tone of a pair was evident in the frequency ranges with separations of 40-200 Hz. In the lowest frequency range, the bias was for perceiving the higher tone in the right ear. This restricted ear advantage in the perception of pure tones was not significantly related to the right-ear advantage in dichotic word monitoring.     

Visual masking effects on duration,size, and form discrimination

In duration, size, and form discrimination tasks, a visual noise mask was presented at variable delays after stimulus offset in order to interrupt processing and control the extent of processing time. Previous work (Thomas & Cantor, 1975) had suggested that both perceived duration and perceived nontemporal “information” might be expected to increase as processing time was extended. As predicted, accuracy in the discrimination of size of circles and form of non-sense figures was found to vary directly with stimulus duration (20, 50 msec) and mask delay interval (0, 30, 70, 110 msec). Differences in perceived duration between filled (forms or circles) and unfilled (blank) intervals were found to increase monotonically with increases in the mask delay interval, when non-sense forms, but not circles, were presented. Two hypotheses of visual masking (“integration” and “interruption”) are discussed. Within the context of the “integration” hypothesis, a model is proposed which predicts processing time as a function of stimulus duration, mask delay interval, and the interval between onset of the mask and termination of processing.     

Contrast effects do not underlie effects of preceding liquids on stop-consonant identification by humans

These experiments explored the claim by A. Lotto and K. Kluender (1998) that frequency contrast explains listeners' compensations for coarticulation in the case of liquid consonants coarticulating with following stops. Evidence of frequency contrast in experiments that tested for it directly was not found, but Lotto and Kluender's finding that high- and low-frequency precursor tones can produce contrastive effects on stop-consonant judgments were replicated. The effect depends on the amplitude relation of the tones to the third formant (F3) of the stops. This implies that the tones mask F3 information in the stop consonants. It is unknown whether liquids and following stops in natural speech are in an appropriate intensity relation for masking of the stop. A final experiment, exploiting the McGurk effect, showed compensation for coarticulation by listeners when neither frequency contrast nor masking can be the source of the compensations.     

The effect of exogenous spatial attention on auditory information processing

This study investigated the effect of exogenous spatial attention on auditory information processing. In Experiments 1, 2 and 3, temporal order judgment tasks were performed to examine the effect. In Experiment 1 and 2, a cue tone was presented to either the left or right ear, followed by sequential presentation of two target tones. The subjects judged the order of presentation of the target tones. The results showed that subjects heard both tones simultaneously when the target tone, which was presented on the same side as the cue tone, was presented after the target tone on the opposite side. This indicates that spatial exogenous attention was aroused by the cue tone, and facilitated subsequent auditory information processing. Experiment 3 examined whether both cue position and frequency influence the resulting information processing. The same effect of spatial attention was observed, but the effect of attention to a certain frequency was only partially observed. In Experiment 4, a tone fusion judgment task was performed to examine whether the effect of spatial attention occurred in the initial stages of hearing. The result suggests that the effect occurred in the later stages of hearing.     

A recognition masking study of consonant processing

The processing of consonants was investigated in a series of experiments using a recognition masking paradigm. Experiment I investigated the effects of target duration, interstimulus interval, forward vs. backward masking, and the phonetic feature composition of the target and mask on accuracy of target identification. Experiment II assessed consonant processing when the target and mask were presented dichotically in order to separate central and peripheral components of consonant masking. Experiment III investigated the effects of mask duration on consonant processing. Substantial masking was found in backward and forward diotic and dichotic conditions. Evidence for target-mask interaction at the level of phonetic features was also found.     

Separate "what" and "where" decision mechanisms in processing a dichotic tonal sequence.

Right-handed subjects were presented with a dichotic tonal sequence, whose basic pattern consisted of three 800-Hz tones followed by two 400-Hz tones on the channel and simultaneously three 400-Hz tones followed by two 800-Hz tones on the other. All tones were 250 msec in duration and separated by 250-msec pauses. On any given stimulus presentation, most subjects reported the sequence of pitches delivered to one ear and ignored the other. They further tended significantly to report the sequence delivered to the right ear rather than to the left. However, each tone appeared to be localized in the ear receiving the higher frequency, regardless of which ear was followed for pitch and regardless of whether the higher or lower frequency was in fact perceived.