Auditory Backward Recognition Masking Research Articles

The effects of unmodulated carrier fringes on the detection of frequency modulation

Detection thresholds for 100 ms of either 5- or 20-Hz frequency modulation (FM) were measured at various temporal positions within a 600-ms, 4-kHz pure-tone carrier. The results indicated that the temporal position of the signal relative to the fringe influences detection thresholds, including an effect that is reminiscent of auditory backward recognition masking. A task involving frequency increments, rather than sinusoidal FM, yielded similar results. Additional manipulation of total carrier duration indicated that FM detection thresholds improve as the duration of the forward fringe increases, while a backward fringe only degrades performance in the absence of any forward fringe. The results suggest that listeners are insensitive to subtle frequency changes that occur at the onset of a longer stimulus and that the interaction between the opposing effects of the forward and backward fringes is not additive.

Backward recognition masking as a general type of interference in needed poststimulus processing

Auditory backward recognition masking (ABRM) has been argued to reflect interference in the storage and/or processing of a short-lived sensory form of information and has been viewed as a relatively invariant attribute of auditory pitch processing for very brief stimuli that are minimally separated in frequency (DeltaF). In contrast, the present study demonstrates that ABRM reflects interference with several basic principles of auditory processing. Measured in terms of target tone duration, rather than DeltaF, ABRM is demonstrated for target stimuli representing the interval of a musical fifth and masker-target stimulus intervals of a musical third, with thresholds ranging from approximately 22 to 55 msec and psychometric functions that are indicative of more than one contributing factor. On the basis of common underlying principles, the possibility that the threshold for the identification of temporal order of onset reflects ABRM and possible implications for the perception of complex stimuli, including speech, are discussed.

Could backward recognition masking play an important role in speech contrasts?

Auditory backward recognition masking (BRM) is the interference in recognition by a following stimulus for some aspect of a clearly detectable target. BRM has been studied for stationary targets, with its conjectured relevance largely limited to the sensory storage and encoding of simple (nonspeech) auditory properties. Could BRM play an important role for more complex stimuli—specifically speech contrasts? The current study systematically investigates BRM interference for speechlike analogs of F2 transitions in varying spectral context that mimic the properties of speech contrasted by place of articulation. Initial and final transitions in isolation show equivalent recognition. Adding a vowel F2 equivalent significantly increases thresholds for initial, but not final, transitions. The further addition of a vowel F1 equivalent results in an additional significant increase in threshold for initial position transitions, and a significant decrease for final position transitions. The possible importance of BRM in defining speech contrasts is discussed. [Work supported by NSF.]

Which People with Specific Language Impairment have Auditory Processing Deficits?

An influential theory attributes developmental disorders of language and literacy to low‐level auditory perceptual difficulties. However, evidence to date has been inconsistent and contradictory. We investigated whether this mixed picture could be explained in terms of heterogeneity in the language‐impaired population. In Experiment 1, the behavioural responses of 16 people with specific language impairment (SLI) and 16 control listeners (aged 10 to 19 years) to auditory backward recognition masking (ABRM) stimuli and unmasked tones indicated that a subgroup of people with SLI are less able to discriminate between the frequencies of sounds regardless of their rate of presentation. Further, these people tended to be the younger participants, and were characterised by relatively poor nonword reading. In Experiment 2, the auditory event‐related potentials (ERPs) of the same groups to unmasked tones were measured. Listeners with SLI tended to have age‐inappropriate waveforms in the N1‐P2‐N2 region, regardless of their auditory discrimination scores in Experiment 1. Together, these results suggest that SLI may be characterised by immature development of auditory cortex, such that adult‐level frequency discrimination performance is attained several years later than normal.

Auditory temporal order discrimination and backward recognition masking in adults with dyslexia.

The ability of 20 adult dyslexic readers to extract frequency information from successive tone pairs was compared with that of IQ-matched controls using temporal order discrimination and auditory backward recognition masking (ABRM) tasks. In both paradigms, the interstimulus interval (ISI) between tones in a pair was either short (20 ms) or long (200 ms). Temporal order discrimination was better for both groups of listeners at long than at short ISIs, but no group differences in performance were observed at either ISI. Performance on the ABRM task was also better at long than at short ISIs and was influenced by variability in masker frequency and by the spectral proximity of target and masker. The only significant group difference was found in one condition of the ABRM task when the target-masker interval was 200 ms, but this difference was not reliable when the measure was of optimal performance. Moderate correlations were observed between auditory thresholds and phonological skill for the sample as a whole and within the dyslexic and control groups. However, although a small subgroup of dyslexic listeners with poor phonology was characterized by elevated thresholds across the auditory tasks, evidence for an association between auditory and phonological processing skills was weakened by the finding of a subgroup of control listeners with poor auditory processing and normal phonological processing skills.

Event-related potentials reflect individual differences in age-invariant auditory skills.

Previous work has found that auditory event-related potentials show maturational changes, with latency and amplitude of late components (N1 and P2) decreasing and increasing with age respectively. Our goal was to test the hypothesis that these changes reflect increased speed of neural processing in the auditory system. Thirty-three listeners, aged 10-50 years, were tested on a frequency discrimination task and an auditory backward recognition masking task. P1 and N1b event-related potential components were measured to tones. The N1b became larger and earlier with age, and the latency of P1 decreased with age. However, thresholds on the behavioural tasks did not change with age. Nevertheless, individual differences in the peak amplitude of N1b were independently related to frequency discrimination and degree of masking. Thus, the relationship that does exist between individual differences in psychoacoustic performance and the auditory N1b reflect a stable characteristic of the individual rather than a maturational change.

Auditory backward recognition masking in children with a specific language impairment and children with a specific reading disability.

The auditory backward recognition masking (ABRM) and intensity discrimination (ID) thresholds of children with a specific language impairment and poor reading (SLI-poor readers), children with an SLI and average reading (SLI-average readers), children with a specific reading disability and average spoken language skills (SRD-average language), and children with normal spoken and written language (controls) were estimated with "child-friendly" psychophysical tasks. The pattern of ABRM and ID scores suggests that a subset of children with concomitant oral language and reading impairments has poor ABRM thresholds, and that a subgroup of children with an SLI or SRD has poorer ID thresholds than controls. The latter result warns against using rapid auditory processing tasks that do not actively control for auditory discrimination ability. Further, some unusually poor ABRM scores and ID scores question the validity of extreme scores produced by children on psychophysical tasks. Finally, the poor oral language scores of many of the children who had impaired reading highlight the need to test the oral language skills of SRD samples to ascertain how homogeneous and specifically disabled they really are.

Neuronal mechanisms of auditory backward recognition masking in macaque auditory cortex.

The sensation of a single sound event can be altered by subsequent sounds. This study searched for neural mechanisms of such retroactive effects in macaque auditory cortex by comparing neural responses to single tones with responses to two consecutive tones. Retroactive influences were found to affect late parts of the response to a tone, which comprised 53/134 of the recordings of action potentials and 88/131 of the recordings of field potentials performed in primary, caudal, and medial auditory fields. If before or during the occurrence of the late response to the first tone a second tone was presented the late response was suppressed. Suppression of late cortical responses parallels perceptual phenomena like backward recognition masking, suggesting that suppression of late responses provides a neural correlate of auditory backward effects.

Auditory backward recognition masking: Influence of musical meaning on pitch relationship between first and second sounds

Auditory backward recognition masking (ABRM) refers to the interference of a second sound on recognition of another sound presented earlier in time. The influence of musical meaning on recognition of the first sound was investigated using the stimuli where the pitch relationship between the first and second sounds composed a triad. Four complex tones consisting of three tones differing in pitch were presented as stimuli. The frequency relationship of two complex tones composed a triad. The others did not compose a triad. One of the three tones of the complex tones was employed as a first sound. The others were employed as a second sound. The task was to label the stimuli as one of the four complex tones. The effect of the differences in the stimuli was evaluated using the percentage of correct responses as a function of ISI. Backward recognition masking was observed with the two sounds that did not compose a triad. The performance was better when the two sounds composed a triad rather than when they did not compose a triad. The results indicated that interference of a second sound on recognition of a first sound is reduced when there is musical meaning in the pitch relationship between the first and second tones.

A test of an interruption/temporal-uncertainty theory of auditory backward recognition masking of target duration

The present study examined auditory backward masking in a task requiring subjects to label a target sound as having a long or short duration. Perception of target duration was influenced by the interaction of the effects of (1) the similarity of the target/mask duration, (2) the acoustic similarity of the target and mask (tone vs. white noise), and (3) the interstimulus interval (ISI) between the target and mask. Specifically, relative to the long duration (100 ms) mask, the short duration (40 ms) mask helped performance for the target having a similar short duration (55 ms) but hurt performance for the target having a dissimilar long duration (85 ms). This effect of the similarity of target/mask duration was greater for acoustically similar targets and masks than for acoustically dissimilar targets and masks, and particularly so at the intermediate (45, 105, 165, 205 ms) ISIs. These results can be explained within the framework of Massaro and Idson's (1976) two-stage model by assuming that masking of perceived auditory duration is the result of two processes: (a) the mask's interruption of target processing in a peripheral auditory processing stage, and (b) a confusion of which item is the target vs. the mask, due to temporal uncertainty in the transfer of the target and mask into a central auditory processing stage.

Event-related potentials in auditory backward recognition masking: a new way to study the neurophysiological basis of sensory memory in humans.

Task-irrelevant pairs of short tones were presented to healthy human subjects while electric potentials were recorded from their scalp ('event-related brain potential', ERP). Infrequent increments in the frequency of the first tone of the repetitive tone-pair elicited an extra ERP component termed 'mismatch negativity' (MMN) when the silent interval between the first and second tone of the pair ('inter-tone interval') was long (150, 300, or 400 ms) but not when this interval was short (20 or 50 ms). This effect did not depend on whether the two tones of the tone-pair were presented to the same or to different ears. The present inter-tone interval effect is consistent with the effects of backward-masking on recognition performance in audition, suggesting that the MMN reflects the neurophysiological basis of echoic memory.

Perceptual development and auditory backward recognition masking.

Perceptual development and auditory backward recognition masking.

Perceptual development and auditory backward recognition masking.

Three amplitude-discrimination experiments within a backward masking task were carried out to study whether young children have a slower rate of perceptual processing than do adults. Rate of processing was defined within an explicit model of perceptual performance that allows the investigator to determine if rate is responsible for developmental differences in auditory discrimination. A developmental difference in discrimination ability was compensated for by increasing the psychophysical difference between the test tones in the backward masking task. No developmental differences in rate of perceptual processing were observed. A quantitative model of perceptual processing gave similar estimates for the rate of perceptual processing in children and adult subjects. Although there are differences in discrimination ability, there appear to be no differences in rate of perceptual processing for children and adults. In the present study, we examined the development during childhood of auditory perceptual processing, auditory discrimination in particular. Our concern was with the temporal course of the initial stage of processing involved in encoding and perceptual recognition. There is a popular belief that young children have a slower rate of perceptual processing than do older children for both visual (e.g., Blake, 1974; Morrison, Holmes, & Haith, 1974) and auditory (Tallal, 1973) information. The consequences of such age differences would be particularly significant in the case of auditory processing. That is, in visual pro

Auditory backward recognition masking: Effect of interaural phase on masker efficacy

The effect of interaural phase on pitch and lateralization recognition was examined. Tonal signals were followed by a variable interstimulus interval and an interference tone. Stimuli were presented in a binaural masking-level difference paradigm as a means of manipulating the perceptual location of the signal within the head. In separate tasks, subjects were required to recognize the pitch or location of the signal. The pitch-recognition task resulted in the expected increase in performance as the interstimulus interval increased. There was no effect of interaural phase on pitch-recognition performance. There was no significant effect of interstimulus interval on performance in location recognition. Subjects were proficient at recognizing location of the signal regardless of the interstimulus interval. The data suggest that a strict single-channel interpretation of the preperceptual storage model of backward auditory recognition is inadequate.

Ear of input as a determinant of pitch-memory interference.

Six experiments to evaluate the effect of presentation ear on pitch-memory interference were conducted using undergraduates as listeners. The task was to compare the pitch of two tones that were separated by an interval that included eight interpolated tones; the interpolated tones were presented either ipsilaterally or contralaterally to the presentation ear of the comparison tones. When the ear of interpolated-tone presentations was blocked, and therefore predictable, ipsilateral interference was greater than contralateral. In contrast, when the interpolated-tone presentation ear was varied randomly from trial to trial, ipsilateral and contralateral interferences were equivalent. These results are analogous to results found in previously reported auditory backward recognition masking (ABRM) experiments and suggest that the ABRM effect may be due, in part, to pitch-memory interference. Implications for theories of auditory processing and memory are discussed.

Forward recognition masking: Another look at the “Echo”

Auditory backward recognition masking effects have been interpreted as reflecting the existence of an echoic memory: an unencoded sensory store whose contents decay rapidly and are easily overwritten by succeeding auditory stimulation. However, it is equally likely that masking effects reflect the time course of an early stage of auditory processing. To distinguish these alternative conceptualizations, vowel stimuli were used in a forward recognition masking procedure. The interstimulus interval (ISI) remained constant, while the mask duration (and hence the stimulus-onset asynchrony, SOA) was varied. The simple storage model predicts that the efficacy of a mask is a function of the time between mask offset and target onset (ISI). Since this interval was constant, equal masking effects would be expected at all SOA intervals. The perceptual processing view predicts that target recognition performance would improve with increasing mask duration (increasing SOA). As mask duration/SOA increases, it is likely that processing of the mask would be completed before target onset. The results, and the implications of these findings, will be discussed. [Work supported by NINCDS.]

Aptitude-related differences in auditory information processing: effects of selective attention and tone duration

College students selected for high or low aptitude performed an auditory backward recognition masking task in which tones differed in pitch (770 or 870 Hz) and duration (10, 13 or 20 msec). Ss were required to attend selectively to the pitch but not to the duration of the targets. As predicted, higher aptitude was associated with lower recognition thresholds at all tone durations. Although increased attentional demands impaired recognition thresholds, this had no apparent differential effect on aptitude-related differences in auditory information processing.

Stimulus-based versus performance-based measurement of auditory backward recognition masking.

Estimates of the time required for the extraction of pitch information from auditory memory have been made using the auditory backward recognition masking (ABRM) technique. With this technique, the ability to recognize the pitch of the first of two sequential tones is determined for various delays between the tones. Most investigators have used fixed stimulus values and have measured performance in terms of P(C), the proportion of correct responses. Use of this measure, proportion correct, as the dependent variable is shown in the present studies to yield, for ABRM, duration estimates that are different from those obtained when the same data are evaluated in stimulus terms for a fixed level of performance. The time course of information extraction from auditory memory was found to extend over approximately 100 msec when measured in stimulus terms, in contrast to the 250 msec that has been reported from data expressed as a proportion of correct responses to a fixed stimulus value. The apparently disparate results previously reported are shown to be mutually consistent if monotonic psychophysical functions are assumed to provide an adequate description of performance in ABRM tasks. Several reasons are proposed for preferring the stimulus-based measures of ABRM.

Backward recognition masking as a function of ear of mask presentation.

Two experiments were conducted to determine whether the magnitude of auditory backward recognition masking (ABRM) differed as a function of whether the mask was presented contralaterally or ipsflaterally to the test tone ear; the mask/test tone ear relationship was a blocked variable in the experiments. On a pitch discrimination task, performance was better when a mask was presented contralaterally rather than ipsflaterally. However, in contrast to an earlier study, there was substantial ABRM on contralateral mask trials, although not as much as on ipsilateral trials. The implications of these results for theories of ABRM are discussed.

Aptitude-related differences in auditory recognition masking

An auditory backward recognition masking task (Massaro, 1970) was administered to undergraduates selected for extreme scores on the Scholastic Aptitude Test and the Cattell Culture Fair Intelligence Test. In two experiments, significant group differences were found in threshold interstimulus intervals (ISIs) required for 75% correct tone recognition. High-aptitude subjects required less time for correct identification of target tones as “high” or “low”. They were more able to overcome the constraints imposed on time-dependent information processing by a masking tone. These group differences were interpreted as indicating better information processing efficiency (h (higher signal-to-noise ratio) in the high-aptitude subjects.