Evidence for two pitch encoding mechanisms using a selective auditory training paradigm

The neural mechanisms underlying the perception of pitch, a sensory attribute of paramount importance in hearing, have been a matter of debate for over a century. A question currently at the heart of the debate is whether the pitch of all harmonic complex tones can be determined by the auditory system's using a single mechanism, or whether two different neural mechanisms are involved, depending on the stimulus conditions. When the harmonics are widely spaced, as is the case at high fundamental frequencies (FOs), and/or when the frequencies of the harmonics are low, the frequency components of the sound fall in different peripheral auditory channels and are then "resolved" by the peripheral auditory system. In contrast, at low F0s, or when the harmonics are high in frequency, several harmonics interact within the passbands of the same auditory filters, being thus "unresolved" by the peripheral auditory system. The idea that more than one mechanism mediates the encoding of pitch depending on the resolvability status of the harmonics was investigated here by testing for transfer of learning in F0 discrimination between different stimulus conditions involving either resolved or unresolved harmonics after specific training in one of these conditions. The results, which show some resolvability-specificity of F0-discrimination learning, support the hypothesis that two different underlying mechanisms mediate the encoding of the F0 of resolved and unresolved harmonics.     

It all sounds the same to me: Sequential ERP and behavioral effects during pitch and harmonicity judgments

The representation of complex sounds was examined by comparing both behavioral and event-related brain potentials (ERPs) to the change or repetition of fundamental frequency (f0) and harmonicity. In the pitch task, participants were asked to categorize the incoming stimulus as either low or high, regardless of harmonicity, and in the harmonicity task, participants indicated whether the stimulus was tuned or mistuned, regardless of pitch. Over three experiments, participants were faster in responding to pitch than to harmonicity. As a result of this asymmetry, behavioral and ERP data showed that irrelevant changes in harmonicity had little impact on performance during the pitch task, whereas harmonicity judgments were impeded by irrelevant changes in f0. These data are consistent with both general horse-race accounts of processing and specific accounts of mistuning detection that posit prior f0 registration. In addition, ERP components N2 and P3 were modulated by both intertrial contingency and task instructions, revealing the further influence of top-down mechanisms on concurrent sound segregation.     

Brief pitch-priming facilitates infants’ discrimination of pitch-evoking noise: Evidence from event-related potentials

Pitch is derived by the auditory system through complex spectrotemporal processing. Pitch extraction is thought to depend on both spectral cues arising from lower harmonics that are resolved by cochlear filters in the inner ear, and on temporal cues arising from the pattern of action potentials contained in the cochlear output. Adults are capable of extracting pitch in the absence of robust spectral cues, taking advantage of the temporal cues that remain. However, recent behavioral evidence suggests that infants have difficulty discriminating between stimuli with different pitches when resolvable spectral cues are absent. In the current experiments, we used the mismatch negativity (MMN) component of the event related potential derived from electroencephalographic (EEG) recordings to examine a cortical representation of pitch discrimination for iterated rippled noise (IRN) stimuli in 4- and 8-month-old infants. IRN stimuli are pitch-evoking sounds generated by repeatedly adding a segment of white noise to itself at a constant delay. We created IRN stimuli (delays of 5 and 6 ms creating pitch percepts of 200 and 167 Hz) and high-pass filtered them to remove all resolvable spectral pitch cues. In experiment 1, we did not find EEG evidence that infants could detect the change in the pitch of these IRN stimuli. However, in Experiment 2, after a brief period of pitch-priming during which we added a sine wave component to the IRN stimulus at its perceived pitch, infants did show significant MMN in response to pitch changes in the IRN stimuli with sine waves removed. This suggests that (1) infants can use temporal cues to process pitch, although such processing is not mature and (2) that a short amount of pitch-priming experience can alter pitch representations in auditory cortex during infancy.     

汉字刺激质量和频率在N400上的交互

采用事件相关电位,运用无启动的同一字判断（靶字延迟反应）范式,以大学生为被试探讨汉字刺激质量和频率是否具有交互作用。行为结果显示,刺激质量和频率在反应时上存在交互作用。脑电结果显示,重度模糊诱发了更大的N250和N400,且刺激质量和频率在N400上存在交互作用。结论是,汉字刺激质量和频率在反应时和N400上存在交互作用,表明在汉字识别中存在串级加工,支持IA模型。     

Implicit chord processing and motor representation in pianists

The aim of this paper is to assess the relevance of pitch dimension in auditory–motor interaction. Several behavioural and brain imaging studies have shown that auditory processing of sounds can activate motor representations, an effect which is however elicited only by action-related sounds, i.e., sounds linked to a specific motor repertoire. Music provides an appropriate framework for further exploration of this issue. Three groups of participants (pianists, non-pianist musicians and non-musicians) were tested with a shape decision task where left-hand and right-hand responses were required; each visual stimulus was paired with an auditory task-irrelevant stimulus (high-pitched or low-pitched piano-timbre chords). Of the three groups, only pianists had longer reaction times for left-hand/high-pitched chords and right-hand/low-pitched chords associations. These findings are consistent with an auditory-motor effect elicited by pitch dimension, as only pianists show an interaction between motor responses and implicit pitch processing. This interaction is consistent with the canonical mapping of hand gestures and pitch dimension on the piano keyboard. The results are discussed within the ideo-motor theoretical framework offered by the Theory of Event Coding (Hommel et al. in Behav Brain Sci 24:849–937, 2001).     

An investigation of spatial representation of pitch in individuals with congenital amusia

Spatial representation of pitch plays a central role in auditory processing. However, it is unknown whether impaired auditory processing is associated with impaired pitch–space mapping. Experiment 1 examined spatial representation of pitch in individuals with congenital amusia using a stimulus–response compatibility (SRC) task. For amusic and non-amusic participants, pitch classification was faster and more accurate when correct responses involved a physical action that was spatially congruent with the pitch height of the stimulus than when it was incongruent. However, this spatial representation of pitch was not as stable in amusic individuals, revealed by slower response times when compared with control individuals. One explanation is that the SRC effect in amusics reflects a linguistic association, requiring additional time to link pitch height and spatial location. To test this possibility, Experiment 2 employed a colour-classification task. Participants judged colour while ignoring a concurrent pitch by pressing one of two response keys positioned vertically to be congruent or incongruent with the pitch. The association between pitch and space was found in both groups, with comparable response times in the two groups, suggesting that amusic individuals are only slower to respond to tasks involving explicit judgments of pitch.     

Stimulus information vs processing time in auditory pattern recognition

Previous studies have shown that pitch perception improves with increases in tone duration. An increase in tone duration increases the information available in the stimulus presentation. Other recent experiments have shown that sufficient perceptual processing time is also necessary for accurate pitch perception. The present study determines the relative contribution of stimulus information and processing time in an absolute pitch indentification task. The results indicate that processing time is more critical than stimulus information. The results are described accurately by a model that describes the perceptual process in terms of the information in the stimulus and the time the information is available for perceptual processing.     

Prenatal daily musical exposure is associated with enhanced neural representation of speech fundamental frequency: Evidence from neonatal frequency-following responses

Fetal hearing experiences shape the linguistic and musical preferences of neonates. From the very first moment after birth, newborns prefer their native language, recognize their mother's voice, and show a greater responsiveness to lullabies presented during pregnancy. Yet, the neural underpinnings of this experience inducing plasticity have remained elusive. Here we recorded the frequency-following response (FFR), an auditory evoked potential elicited to periodic complex sounds, to show that prenatal music exposure is associated to enhanced neural encoding of speech stimuli periodicity, which relates to the perceptual experience of pitch. FFRs were recorded in a sample of 60 healthy neonates born at term and aged 12–72 hours. The sample was divided into two groups according to their prenatal musical exposure (29 daily musically exposed; 31 not-daily musically exposed). Prenatal exposure was assessed retrospectively by a questionnaire in which mothers reported how often they sang or listened to music through loudspeakers during the last trimester of pregnancy. The FFR was recorded to either a /da/ or an /oa/ speech-syllable stimulus. Analyses were centered on stimuli sections of identical duration (113 ms) and fundamental frequency (F₀ = 113 Hz). Neural encoding of stimuli periodicity was quantified as the FFR spectral amplitude at the stimulus F₀. Data revealed that newborns exposed daily to music exhibit larger spectral amplitudes at F₀ as compared to not-daily musically-exposed newborns, regardless of the eliciting stimulus. Our results suggest that prenatal music exposure facilitates the tuning to human speech fundamental frequency, which may support early language processing and acquisition.

Research Highlights

• Frequency-following responses to speech were collected from a sample of neonates prenatally exposed to music daily and compared to neonates not-daily exposed to music.
• Neonates who experienced daily prenatal music exposure exhibit enhanced frequency-following responses to the periodicity of speech sounds.
• Prenatal music exposure is associated with a fine-tuned encoding of human speech fundamental frequency, which may facilitate early language processing and acquisition.

     

Periodicity within reaction time distributions and electromyograms

This study investigates a periodic component in reaction time frequency distributions, that is, a tendency for responses to occur at regular, discrete intervals of time after stimulus presentation. Reaction time frequency distributions were plotted by a Computer of Average Transients and were obtained under stimulus conditions varying in sense modality stimulated (auditory and visual), and the intensity, colour, and duration of stimulation. The results indicated that there was periodicity in reaction time frequency distributions with a modal period of approximately 25 msec. It was found that the periodicty (a) was most evident when there was considerable variability in reaction time, and (b) tended to attenuate when a large number of reaction times were grouped. Other stimulus conditions appeared to have little effect on the periodicity. A significant correlation was found between the frequency of periodicity in the reaction time distributions and the electromyograms, both having a modal period of 25 msec. It was concluded that the periodicity in reaction time was the result of motor processes.     

Evidence for reduced domain-specificity in auditory processing in autism

Neurological and behavioral findings indicate that atypical auditory processing characterizes autism. The present study tested the hypothesis that auditory processing is less domain-specific in autism than in typical development. Participants with autism and controls completed a pitch sequence discrimination task in which same/different judgments of music and/or speech stimulus pairs were made. A signal detection analysis showed no difference in pitch sensitivity across conditions in the autism group, while controls exhibited significantly poorer performance in conditions incorporating speech. The results are largely consistent with perceptual theories of autism, which propose that a processing bias towards featural/low-level information characterizes the disorder, as well as supporting the notion that such individuals exhibit selective attention to a limited number of simultaneously presented cues.     

Brief pitch-priming facilitates infants’ discrimination of pitch-evoking noise: Evidence from event-related potentials

Pitch is derived by the auditory system through complex spectrotemporal processing. Pitch extraction is thought to depend on both spectral cues arising from lower harmonics that are resolved by cochlear filters in the inner ear, and on temporal cues arising from the pattern of action potentials contained in the cochlear output. Adults are capable of extracting pitch in the absence of robust spectral cues, taking advantage of the temporal cues that remain. However, recent behavioral evidence suggests that infants have difficulty discriminating between stimuli with different pitches when resolvable spectral cues are absent. In the current experiments, we used the mismatch negativity (MMN) component of the event related potential derived from electroencephalographic (EEG) recordings to examine a cortical representation of pitch discrimination for iterated rippled noise (IRN) stimuli in 4- and 8-month-old infants. IRN stimuli are pitch-evoking sounds generated by repeatedly adding a segment of white noise to itself at a constant delay. We created IRN stimuli (delays of 5 and 6 ms creating pitch percepts of 200 and 167 Hz) and high-pass filtered them to remove all resolvable spectral pitch cues. In experiment 1, we did not find EEG evidence that infants could detect the change in the pitch of these IRN stimuli. However, in Experiment 2, after a brief period of pitch-priming during which we added a sine wave component to the IRN stimulus at its perceived pitch, infants did show significant MMN in response to pitch changes in the IRN stimuli with sine waves removed. This suggests that (1) infants can use temporal cues to process pitch, although such processing is not mature and (2) that a short amount of pitch-priming experience can alter pitch representations in auditory cortex during infancy.     

Visual-auditory interaction in speeded classification: Role of stimulus difference

An experiment examined cross-modal interference and congruence in speeded classification: Subjects had to identify compound (visual-auditory) stimuli as either low or high in spatial position (visual judgment) or low or high in pitch (auditory judgment), in 16 conditions, each of which combined one of four possible pairs of tones, varying in frequency difference, with one of four possible pairs of dots, varying in positional difference. Both classification by position and classification by pitch revealed Garner interference (poorer performance than baseline, with orthogonal variation in the irrelevant dimension) and congruence effects (better performance with congruent than with incongruent stimulus combinations), but pitch classification showed more. Furthermore, the size of the pitch difference strongly affected classification by pitch and less strongly affected classification by position, but the size of the position difference affected neither. The findings are consistent with the view that Garner interference and congruence effects are closely related, perhaps arising from a common source, and suggest that the asymmetries could depend in part on the degree of dimensional overlap between stimuli and responses.     

Sensory features and the reduction of imaginal interference

Interference generated among the sensory features of PA stimulus words is not eliminated by processing at the imaginal level. This experiment was planned to test the reverse possibility. Will interference generated by similar imaginal referents be eliminated by sensory overlap between the stimuli and their responses? Thus, stimulus words did or did not evoke similar images, pairs did or did not share initial letters, and lists were acquired either under an instructional set t o form interacting images or to repeat the items aloud. The results indicated that the imagery strategy was superior to the repetition strategy in all conditions, and that stimulus interference was statistically eliminated when pairs shared the same initial letters. The findings were interpreted as consistent with a levels of processing conceptualization.     

Categorizing sounds by pitch: effects of stimulus similarity and response repetition

Two experiments were performed to determine whether categorization of the pitch of a probe tone is influenced by the pitch of, and response made to, a preceding prime tone. The prime and the probe could be drawn either from a pool of low-frequency sounds or from a pool of high-frequency sounds. The results of both experiments indicated that the performance obtained was best when the prime and the probe were the same pitch (and therefore required the same response), intermediate when the two sounds differed in pitch and required different responses, and slowest when the prime and the probe differed in pitch but required the same response (i.e., they were drawn from the same frequency pool). The results of Experiment 2 revealed in addition that when a repeated response was required, performance declined as the magnitude of the frequency change increased and that responses were made more quickly and accurately if the direction of the frequency change was away from the alternative category than if it was toward the alternative category. The results demonstrate that categorization of sounds by pitch is accomplished with reference to a previous processing episode.     

Task choice and semantic interference in picture naming

Evidence from dual-task performance indicates that speakers prefer not to select simultaneous responses in picture naming and another unrelated task, suggesting a response selection bottleneck in naming. In particular, when participants respond to tones with a manual response and name pictures with superimposed semantically related or unrelated distractor words, semantic interference in naming tends to be constant across stimulus onset asynchronies (SOAs) between the tone stimulus and the picture–word stimulus. In the present study, we examine whether semantic interference in picture naming depends on SOA in case of a task choice (naming the picture vs reading the word of a picture–word stimulus) based on tones. This situation requires concurrent processing of the tone stimulus and the picture–word stimulus, but not a manual response to the tones. On each trial, participants either named a picture or read aloud a word depending on the pitch of a tone, which was presented simultaneously with picture–word onset or 350 ms or 1000 ms before picture–word onset. Semantic interference was present with tone pre-exposure, but absent when tone and picture-word stimulus were presented simultaneously. Against the background of the available studies, these results support an account according to which speakers tend to avoid concurrent response selection, but can engage in other types of concurrent processing, such as task choices.     

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.     

Referential coding contributes to the horizontal SMARC effect

The present study tested whether coding of tone pitch relative to a referent contributes to the correspondence effect between the pitch height of an auditory stimulus and the location of a lateralized response. When left-right responses are mapped to high or low pitch tones, performance is better with the high-right/low-left mapping than with the opposite mapping, a phenomenon called the horizontal SMARC effect. However, when pitch height is task irrelevant, the horizontal SMARC effect occurs only for musicians. In Experiment 1, nonmusicians performed a pitch discrimination task, and the SMARC effect was evident regardless of whether a referent tone was presented. However, in Experiment 2, for a timbre-judgment task, nonmusicians showed a SMARC effect only when a referent tone was presented, whereas musicians showed a SMARC effect that did not interact with presence/absence of the referent. Dependence of the SMARC effect for nonmusicians on a reference tone was replicated in Experiment 3, in which judgments of the color of a visual stimulus were made in the presence of a concurrent high- or low-pitched pure tone. These results suggest that referential coding of pitch height is a key determinant for the horizontal SMARC effect when pitch height is irrelevant to the task.     

Pitch and pitch change interact in auditory displays

Designing auditory displays requires understanding how different attributes of sound are processed. Operators must often listen to a particular stimulus dimension and make control actions contingent on the auditory information. Three experiments used a selective-listening paradigm to examine interactions between auditory dimensions. Participants were instructed to attend to either relative pitch or direction of pitch change of dynamic stimuli. With vertically arranged keypress responses, reactions to both dimensions showed stimulus-response compatibility effects, indicating that pitch is treated spatially. Direction of pitch change affected responses to pitch; level of pitch more strongly affected responses to pitch change. To reduce deleterious effects of irrelevant pitch information, auditory display designers can restrict the pitch range used to display dynamic data.     

人脸加工中身份语义信息提取的加工方式

人脸加工过程中,从人脸知觉到身份信息提取是一个系列的过程还是平行加工的过程,是人脸研究的热点问题之一。通过比较脸—脸(FF)、名字—名字(NN)、脸—名字(FN)和名字—脸(NF)等四种刺激类型条件下被试对其作夫妇判断和性别配对判断时的反应时分析,发现判断任务与刺激类型之间存在显著交互作用。在性别判断任务中,FF反应最快,NF其次,FN和NN最慢;而在夫妇判断任务中,四种刺激类型间无显著差异。反应错误率分析也显示相似的结果。实验结果支持人脸识别到身份信息提取过程为系列加工的观点。     

Some perceptual dependencies in speeded classification of vowel color and pitch

Wood (1975) suggested that information specifying consonant identity is dependent on the earlier processing of pitch. Is vowel identification also dependent on the prior processing of pitch? In contrast with the results obtained with consonants, Kuhl (1975, 1976) reported that infants responded selectively to differences in vowel color when pitch varied but not to differences in pitch when vowel color varied. Miller (1978) has also reported that adults show mutual, symmetric interference effects in speeded classification of vowel color and pitch, In the present study, judgments of vowel color and pitch were examined in a reaction time task in order to assess the effects of the relative discriminability of vowel and pitch quality on speeded classification. In addition, we also compared the classification of isolated vowels to vowels in consonantal context. The overall results were consistent with both Kuhl’s and Miller’s earlier findings but refine our understanding of the interaction between various dimensions by showing that vowel identification is also dependent on the processing of pitch information. Such an interaction, however, becomes evident only when the processing dependencies are examined across a wide range of stimulus values for each dimension. The present findings provide additional information about the nature of processing dependencies among dimensions in speech and the methods by which such dependencies may be studied.