Backward Recognition Masking Research Articles

Backward recognition masking of similar and dissimilar environmental sounds

Backward Recognition Masking (BRM) of sound occurs when two sounds are presented close in time to one another and the second sound hinders the recognition of the first sound. Previous studies on BRM used either white noise or sine tones. Here, we present backward recognition thresholds using environmental sounds. 34 young normal hearing individuals were presented with 6 combinations of similar or dissimilar environmental sounds from the categories of household appliances, automobiles, and power tools. The sounds were selected based on their multi-dimensional scaling distances (Rosen et al., 2017). The sounds were presented at 20 dB SL re: 3 frequency PTA and the inter stimulus interval was fixed at 22.2 ms. A two-down one-up adaptive procedure was used to identify the target duration at which the listeners could identify that the target is different from the masker. Initial data analyses indicated that similar sounds needed significantly longer presentation durations to be identified as different compared to dissimilar sounds, indicating more backward masking for similar sounds compared to dissimilar sounds. These results potentially highlight how critical safety information in real-world environments may be missed in complex listening scenarios.

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.

The influence of later-arriving sounds on the ability of listeners to judge the lateral position of a source

This study examined the deleterious effects of a later-arriving sound on the processing of interaural differences of time (IDTs) from a preceding sound. A correlational analysis assessed the relative weight given to IDTs of source and echo clicks for echo delays of 1-64 ms when the echo click was attenuated relative to the source click (0-36 dB). Also measured were proportion correct and the proportion of responses predicted from the weights. The IDTs of source and echo clicks were selected independently from Gaussian distributions (mu=0 s, sigma = 100/s). Listeners were instructed to indicate the laterality of the source click. Equal weight was given to the source and echo clicks for echo delays of 64 ms with no echo attenuation. For echo delays of 16-64 ms, attenuating the echo had no substantial effect on source weight or proportion correct until the echo was attenuated by 18-30 dB. At echo delays < or =4 ms, source weights and proportions correct remained high regardless of echo attenuation. The proportions of responses predicted from the weights were lower at echo delays > or =16 ms. Results were discussed in terms of backward recognition masking and binaural sluggishness and compared to measurements of echo disturbance.

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.]

The reliability and validity of tasks measuring perception of rapid sequences in children with dyslexia.

Claims that children with reading and oral language deficits have impaired perception of sequential sounds are usually based on psychophysical measures of auditory temporal processing (ATP) designed to characterise group performance. If we are to use these measures (e.g., the Tallal, 1980, Repetition Test) as the basis for intervention in language and literacy deficits, we need to demonstrate that they can effectively quantify individual differences. Therefore, questions of standardisation, reliability and construct validity can no longer be ignored. We explored these issues in three studies: (i) 52 Dyslexics and Good Readers aged 8 to 11 years performed a task requiring perception of rapid sequences (PRS) based on the Tallal Repetition Test; (ii) a subgroup of the initial sample was retested on the task three to four months later, and after extended practice; (iii) a further subgroup then completed a rate of auditory processing task using a backward recognition masking paradigm. With a standardised methodology, we were able to replicate previous results with the PRS task, and demonstrate moderate reliability of measurement across time and practice. However, there were large effects of exposure and practice, and the task did not seem useful for identifying absolute and continuing deficits in given individuals. Our results call into question the use of this type of task as an individual measure of ATP. Neither is it certain that it is capturing what is currently understood as ATP.

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.

Recognition masking for transitions in initial and final position

There is a common implicit assumption that the input to higher or specialized processes is accurately represented by the physical properties of the stimulus, with, at most, only detection masking and some basic initial filtering. Since playing an auditory stimulus backwards does not alter the spectral composition of the stimuli, this initial assumption has led to the conclusion that any differences in perception must be attributed to higher level or specialized processes. Thus, for example, significant differences in the perception of temporally reversed CV syllables are assumed to reflect only specialized processes (i.e., speech module). The current study challenges this basic implicit assumption. Backward ‘‘recognition’’ masking is a basic, but poorly understood perceptual phenomenon in which an added following stimulus interferes with discrimination of simple preceding tones. Recent work from our laboratory indicates similar interference in the recognition of easily discriminated chords. The current study investigates the role of backward recognition masking in determining ability to recognize the direction of frequency glides similar to formant transitions of stop consonants.

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 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 [sh] 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 in reverse, 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.

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.