Timbre control in zebra finch (Taeniopygia guttata) song syllables

Zebra finch (Taeniopygia guttata) song syllables often include harmonically related frequency components. These harmonics may be suppressed, and this differential emphasis varies between the syllables in a song and between individual birds' songs. These patterns of harmonic suppression are timbre. Individual syllables' patterns of harmonic suppression are constant with adult males' songs. Young males that imitate the songs of older males also imitate their patterns of harmonic suppression. Syringeal denervation distorts these patterns, which suggests that they are produced through active control of the vocal organ. The selective suppression and emphasis of some harmonics creates a great number of possible timbre variants for any one syllable. These add signal diversity to the limited array of frequency modulations and range of fundamental frequencies found in zebra finch song. Analyses of bird song that disregard timbre may overlook a feature that is important in vocal communication.     

元音和复合声识别中噪声分离机制的实验研究

该文用配对比较方法,从夫调谐波的数量对谐波筛的影响（实验一）、失调谐波的位置（实验二）以及谐波相位与其失调幅度之间的相互作用（实验三）等三个方面对失调谐波的分离机制进行探讨。研究结果表明：（1）多个谐波同时失调时其失调效应要比单个谐波强,即谐波失调存在累积效应;（2）谐波次数不同,其失调效应也存在差异,这种差异与谐波和共振峰之间的距离有关,谐波越靠近共振峰,其失调效应越明显,但对由等振幅的谐波系列构成的复合声而言,高次谐波的失调效应比低次谐波弱;（3）谐波相位对其失调效应产生间接影响,这种影响与谐波的起始振幅有关,当相位为π／2和3π／2时,失调效应更加明显。     

Processing lexically embedded spoken words

A large number of multisyllabic words contain syllables that are themselves words. Previous research using cross-modal priming and word-spotting tasks suggests that embedded words may be activated when the carrier word is heard. To determine the effects of an embedded word on processing of the larger word, processing times for matched pairs of bisyllabic words were examined to contrast the effects of the presence or absence of embedded words in both 1st- and 2nd-syllable positions. Results from auditory lexical decision and single-word shadowing demonstrate that the presence of an embedded word in the 1st-syllable position speeds processing times for the carrier word. The presence of an embedded word in the 2nd syllable has no demonstrable effect.     

Effects of harmonics on relative pitch discrimination in a musical context

The contribution of different harmonics to pitch salience in a musical context was examined by requiring subjects to discriminate a small (1/4 semitone) pitch change in one note of a melody that repeated in transposition. In Experiment 1, performance was superior when more harmonics were present (first five vs. fundamental alone) and when the second harmonic (of tones consisting of the first two harmonics) was in tune compared with when it was out of tune. In Experiment 2, the effects of harmonics 6 and 8, which stand in octave-equivalent simple ratios to the fundamental (2∶3 and 1∶2, respectively) were compared with harmonics 5 and 7, which stand in more complex ratios (4:5 and 4:7, respectively). When the harmonics fused into a single percept (tones consisting of harmonics 1, 2, and one of 5, 6, 7, or 8), performance was higher when harmonics 6 or 8 were present than when harmonics 5 or 7 were present. When the harmonics did not fuse into a single percept (tones consisting of the fundamental and one of 5, 6, 7, or 8), there was no effect of ratio simplicity.     

Planning and articulation in incremental word production: syllable-frequency effects in English

We investigated the role of syllables during speech planning in English by measuring syllable-frequency effects. So far, syllable-frequency effects in English have not been reported. English has poorly defined syllable boundaries, and thus the syllable might not function as a prominent unit in English speech production. Speakers produced either monosyllabic (Experiment 1) or disyllabic (Experiment 2-4) pseudowords as quickly as possible in response to symbolic cues. Monosyllabic targets consisted of either high- or low-frequency syllables, whereas disyllabic items contained either a 1st or 2nd syllable that was frequency-manipulated. Significant syllable-frequency effects were found in all experiments. Whereas previous findings for disyllables in Dutch and Spanish-languages with relatively clear syllable boundaries-showed effects of a frequency manipulation on 1st but not 2nd syllables, in our study English speakers were sensitive to the frequency of both syllables. We interpret this sensitivity as an indication that the production of English has more extensive planning scopes at the interface of phonetic encoding and articulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved).     

Regularity of spectral pattern and its effects on the perceptual fusion of harmonics

A single even harmonic added to an odd-harmonic complex may be judged as perceptually more salient than the odd harmonics themselves (Roberts & Bregman, 1991). It is proposed that this effect occurs because the even harmonic is inconsistent with the regular spectral pattern formed by the odd-harmonic complex (the base). Therefore, a reduction in the regularity of the base spectrum should reduce the even—odd difference. Spectral regularity was reduced either by removing base components, or by including components in the base that were inconsistent with its original pattern. Subjects listened to (primarily) harmonic complex tones and rated the clarity of one of the harmonics, cued by a preceding pure tone. Both removing components from the base and including extraneous components in the base reduced the even—odd difference. The results suggest that it is easier to segregate a harmonic from a periodic complex tone when it does not form part of the regular pattern of spectral spacing defined by the other harmonics.     

The perceptual segregation of simultaneous auditory signals: pulse train segregation and vowel segregation

In the experiments reported here, we attempted to find out more about how the auditory system is able to separate two simultaneous harmonic sounds. Previous research (Halikia & Bregman, 1984a, 1984b; Scheffers, 1983a) had indicated that a difference in fundamental frequency (F0) between two simultaneous vowel sounds improves their separate identification. In the present experiments, we looked at the effect of F0s that changed as a function of time. In Experiment 1, pairs of unfiltered or filtered pulse trains were used. Some were steady-state, and others had gliding F0s; different F0 separations were also used. The subjects had to indicate whether they had heard one or two sounds. The results showed that increased F0 differences and gliding F0s facilitated the perceptual separation of simultaneous sounds. In Experiments 2 and 3, simultaneous synthesized vowels were used on frequency contours that were steady-state, gliding in parallel (parallel glides), or gliding in opposite directions (crossing glides). The results showed that crossing glides led to significantly better vowel identification than did steady-state F0s. Also, in certain cases, crossing glides were more effective than parallel glides. The superior effect of the crossing glides could be due to the common frequency modulation of the harmonics within each component of the vowel pair and the consequent decorrelation of the harmonics between the two simultaneous vowels.     

Hemispheric specialization for speech opposed,by contralateral noise

Twenty right-handed Ss listened to a dichotic tape in which one of six consonant-vowel syllables was paired with a burst of white noise on each trial. Eight blocks of 40 trials were presented, with the syllables within a block presented to, the same ear. On each trial, Ss decided if/ ba/ was presented. Mean RT to right-ear items was 440.0 msec, while mean left-ear RT was 453.6 msec. Responses indicating the presence of /ba/ were made significantly more quickly than responses indicating its absence, with no significant interaction of ear and type of decision. This study demonstrated a right-ear advantage in the perception of spoken syllables when noise is presented to the opposite ear. An interpretation of the RT differences between ears in terms of callosal transmission time is discussed, and implications of this study for the perceptual origins of the ear advantage effect are considered.     

Linguistic boundaries as predictors of the time between letters in oral and typed spellings

The authors investigated the importance of boundaries between phonemes, syllables, onsets and rimes, and morphemes in English spelling. They analyzed oral spelling data from a previous sample of 17 college students to predict time between consecutive letters (pause time) on the basis of the presence or absence of each linguistic boundary. The authors used a parallel approach to analyze pause times of 30 college students when typing individual words and when typing words in an essay. For oral and typed spellings of individual words, syllable boundaries significantly predicted pause times. Phoneme boundaries also predicted pause times in typed spellings of individual words. For typing essays, only onset-rime boundaries significantly predicted pause times. The results support the importance of syllables in the spelling of individual words. Further, the results suggest that spelling in the context of writing is a qualitatively different process than is spelling individual words by dictation.     

Linguistic stress, within-word position, and grammatical class in relation to early childhood stuttering

The purpose of the present study was to investigate whether the link that has been established between stuttering and linguistic stress in adolescents and adults (the so-called stress effect) can also be observed in childhood stuttering. To account for confounding variables, both within-word position and grammatical class were measured, because these factors covary with linguistic stress. Speech samples of 22 preschool children (mean time of 9 months since onset of stuttering) were analyzed. The relative stress of each syllable was rated and syllables were categorized into long and short stressed, unstressed, and intermediately stressed syllables. Results showed that 97.8% of stuttering events occurred on first syllables of words and 76.5% on the first sound of syllables, that means a clear word-initial effect. Stuttering frequency on first syllables of function words was 16.9% and significantly higher than the frequency of stuttered first syllables of content words (11.5%). In function words short stressed syllables and intermediately stressed syllables were stuttered more often than unstressed syllables. The analysis for individual disfluency types revealed that, for function words, stuttering on short stressed syllables was associated with prolongations and syllable repetitions. However, in intermediately stressed syllables stuttering coincided most often with one-syllable word repetitions. This differentiation of the stress effect may suggest different causal mechanisms underlying these disfluency types. Educational objectives: The reader will learn about and be able to: (1) describe how within-word position, grammatical class, and linguistic stress effect stuttering frequency in preschool children who stutter; (2) explain how the occurrence of individual disfluency types depends on linguistic stress; (3) discuss how patterns of adults and preschool children who stutter differ in regard to these aspects.     

Identification of vowels in "vowel-less" syllables by 3-year-olds

The ability of 3-year-old children to perceive the identity of vowels in full-vowel and silent-center, consonant-vowel-consonant (CVC) syllables was investigated using a two-alternative pointing procedure. Silence replaced the middle 10%, 35%, 65%, or 90% of the steady-state formants of synthetic "bad" and "bud" syllables. Identification of the two full-vowel syllables was 87% correct, whereas performance for the silent-center syllables was somewhat lower (72%, 70%, 67%, and 66% correct for the 10%, 35%, 65%, and 90% deletion stimuli, respectively). The performance of individual children fell into two subgroups: (1) those who performed like adults by maintaining correct vowel identification for all of the silent-center syllables, and (2) those who identified the full-vowel syllables correctly but performed at chance for all of the silent-center syllables. Three additional experiments showed that none of the children performed poorly when noise replaced the gap in the silent-center syllables. These results demonstrate that many 3-year-olds can identify vowels correctly in CVC syllables in the absence of the full spectral properties of steady-state formants.     

Identification of vowels in “vowelless” syllables by 3-year-olds

The ability of 3-year-old children to perceive the identity of vowels in full-vowel and silentcenter, consonant-vowel-consonant (CVC) syllables was investigated using a two-alternative pointing procedure. Silence replaced the middle 10%, 35%, 65%, or 90% of the steady-state formants of synthetic “bad” and “bud” syllables. Identification of the two full-vowel syllables was 87% correct, whereas performance for the silent-center syllables was somewhat lower (72%, 70%, 67%, and 66% correct for the 10%, 35%, 65%, and 90% deletion stimuli, respectively). The performance of individual children fell into two subgroups: (1) those who performed like adults by maintaining correct vowel identification for all of the silent-center syllables, and (2) those who identified the full-vowel syllables correctly but performed at chance for all of the silent-center syllables. Three additional experiments showed that none of the children performed poorly when noise replaced the gap in the silent-center syllables. These results demonstrate that many 3-year-olds can identify vowels correctly in CVC syllables in the absence of the full spectral properties of steady-state formants.     

Proper and common nouns: form class judgments in Broca's aphasia

Studies of agrammatic Broca's aphasics' comprehension of sentences containing articles have demonstrated profound deficits. It has not been clear whether the impairments are due to an inability to isolate the article in the stream of speech, or to difficulty in the construction and/or interpretation of various syntactic, semantic, or pragmatic levels of representation. This paper reports three experiments on Broca's aphasics' ability to distinguish between common nouns (e.g., "a rose") and proper nouns (e.g., "Rose"). This grammatical form class decision is signaled by the presence or absence of an article, and is represented at the lexical node level of linguistic analysis. The three experiments demonstrated that Broca's aphasics point to pictures representing classes of objects when asked to point to "the X" and point to pictures representing unique individuals when asked to point to "X". Thus, they were shown to be able to use the presence or absence of an article to determine lexical category. Their performance was especially accurate in an oral language context which was highly redundant and in a written language context where patients themselves could control the rate of information flow. They were quantitatively impaired, relative to controls, in a third study, which made higher information processing demands. Moreover, in this third study nonsense syllables preceding the noun which are phonologically similar to a known article were much more likely to evoke the misclassification of its noun as common than were phonologically distinct nonsense syllables. These data indicate that Broca's aphasics indeed have some difficulty isolating the article in the stream of speech. Nevertheless, detailed analyses of aphasics' performance revealed their ability to distinguish between common nouns and proper nouns even under these demanding conditions. Taken together, the three studies show that insofar as agrammatic patients are able to keep track of the presence or absence of articles, they can make a grammatical decision at the lexical node level of linguistic analysis. We conclude, then, that agrammatic Broca's aphasics are particularly impaired in the use of articles to construct and/or interpret phrasal constituents.     

The Role of Syllables in Anagram Solution: A Rasch Analysis

Anagrams are frequently used by experimental psychologists interested in how the mental lexicon is organized. Until very recently, research has overlooked the importance of syllable structure in solving anagrams and assumed that solution difficulty was mainly due to frequency factors (e.g., bigram statistics). The present study uses Rasch analysis to demonstrate that the number of syllables is a very important factor influencing anagram solution difficulty for both good and poor problem solvers, with polysyllabic words being harder to solve. Furthermore, it suggests that syllable frequency may have an impact on solution times for polysyllabic words, with more frequent syllables being more difficult to solve. The study illustrates the advantages of Rasch analysis for reliable and unidimensional measurement of item difficulty.     

The role of syllables in anagram solution: a Rasch analysis

Anagrams are frequently used by experimental psychologists interested in how the mental lexicon is organized. Until very recently, research has overlooked the importance of syllable structure in solving anagrams and assumed that solution difficulty was mainly due to frequency factors (e.g., bigram statistics). The present study uses Rasch analysis to demonstrate that the number of syllables is a very important factor influencing anagram solution difficulty for both good and poor problem solvers, with polysyllabic words being harder to solve. Furthermore, it suggests that syllable frequency may have an impact on solution times for polysyllabic words, with more frequent syllables being more difficult to solve. The study illustrates the advantages of Rasch analysis for reliable and unidimensional measurement of item difficulty.     

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.     

Perception of missing fundamental by a species of songbird (Sturnus vulgaris)

Two experiments investigated whether a species of songbird perceives missing fundamentals in sounds containing complex frequencies. In Experiment 1, European starlings were trained to discriminate between two sinusoids. This discrimination persisted when the sinusoids were replaced with waveforms composed solely of four consecutive higher harmonics of the training frequencies. In Experiment 2, starlings trained to discriminate between two complex frequencies consisting of sets of higher harmonics transferred the discrimination to the sinusoidal fundamentals. The results demonstrate that starlings can perceive harmonic or periodic structure, and show that a species of songbird can use harmonic structure to gain information about its auditory environment. The findings, together with those obtained from fish and mammals, suggest that periodicity pitch perception may be a general process in vertebrate hearing.     

Listening to speech while retaining music: What happens to the right-ear advantage?

On each trial, subjects were played a dichotic pair of syllables differing in the consonant (/ba/, /da/, /ga/) or in the vowel (/ba/, /b?/, /bi/). The pair of syllables was preceded by a melody, or a sentence, and followed by the same or a different melody, or sentence. Subjects either had to retain the first piece of additional material or were free to ignore it. The different combinations of phonemic contrast, additional material, and instruction concerning the additional material were used in different sessions. In each case, the main task of the subjects was to respond to the presence or the absence of the target /ba/ on the ear previously indicated. There was no effect of context on relative ear accuracy, but the right-ear advantage observed for consonants in response latency when subjects retained a sentence gave way to a small nonsignificant left-ear advantage when subjects retained a melody. Right-ear advantage in response latencies was also observed for vowels in the verbal context, but the contextual effect, although in the same direction as for consonants, was very slight. The implications of contextual effects for a theory of the determinants of the auditory laterality effects are discussed.     

Syllable chunking in zebra finch (Taeniopygia guttata) song.

We examined how 61 young zebra finch (Taeniopygia guttata) males copied song from 5 adult tutors. Zebra finch song consists of a string of 5-15 distinct syllables, and these syllables were copied as chunks, or strings of consecutive syllables (modal length = 3). The silent interval between 2 syllables was copied as part of the syllable after the silence. Copied chunks had boundaries that fell at consistent locations within the tutor's song, marked by a relatively long intersyllable silent period, a transition between call-like and noncall-like syllables, and a tendency for the tutor male to stop his song short. Young males also tended to break their songs off at the boundaries of the chunks they had copied. Chunks appear to be an intermediate level of hierarchy in song organization and to have both perceptual (syllables were learned as part of a chunk) and motor (song delivery was broken almost exclusively at chunk boundaries) aspects.