Target Phrase Research Articles

The influence of target-masker similarity in a three-talker diotic listening task

In diotic cocktail-party listening tasks, performance decreases dramatically when the number of talkers increases from two (one target and one masker) to three (one target and two maskers). In this experiment, listeners were asked to extract information from a Coordinate Response Measure (CRM) target phrase that was masked by one or two interfering utterances. The maskers were either semantically similar to the target (i.e., CRM phrases with different call signs than the target phrase) or semantically different from the target (time-reversed, contextually dissimilar, or in a different language than the target phrase). The two-talker results showed that performance was much worse when the interfering phrase was semantically similar to the target than when it was semantically different. However, given that one interfering talker was similar to the target, the contextual similarity of the second interfering talker had very little effect on performance; in other words, target intelligibility in the presence of two CRM maskers was no worse than with one CRM masker and one time-reversed or foreign-language masker. These results suggest that the disruption of speech segregation caused by the addition of a second interfering talker cannot be explained solely by contextual similarity between the target and masking speech.

Sociological effects on vocal aging: Age related F0 effects in two languages

Listeners can estimate the age of a speaker fairly accurately from their speech (Ptacek and Sander, 1966). It is generally considered that this perception is based on physiologically determined aspects of the speech. However, the degree to which it is due to conventional sociolinguistic aspects of speech is unknown. The current study examines the degree to which fundamental frequency (F0) changes due to advanced aging across two language groups of speakers. It also examines the degree to which the speakers associate these changes with aging in a voice disguising task. Thirty native speakers each of English and Japanese, taken from three age groups, read a target phrase embedded in a carrier sentence in their native language. Each speaker also read the sentence pretending to be 20-years younger or 20-years older than their own age. Preliminary analysis of eighteen Japanese speakers indicates that the mean and maximum F0 values increase when the speakers pretended to be younger than when they pretended to be older. Some previous studies on age perception, however, suggested that F0 has minor effects on listeners’ age estimation. The acoustic results will also be discussed in conjunction with the results of the listeners’ age estimation of the speakers.

GENDER DIFFERENCES IN EMOTIONAL PROSODY PROCESSING-AN FMRI STUDY-

To clarify how the brain understands the speaker’s mind for verbal acts, we analyzed fMRI images obtained from 24 subjects when they judged linguistic meanings or emotional manners of spoken phrases. The target phrases had linguistically positive or negative meanings and were uttered warmheartedly or coldheartedly by a woman speaker. Significant interaction effects of meaning and manner were observed on the acoustic characteristics of utterances, such as F0 range, and also on the perceptual behavior evaluated by response time and judgment correctness. When compared to the female subjects, the male subjects showed significantly stronger activation only in the right frontomedian cortex, which can be hypothesized to analyze and understand speaker’s hidden but true intentions from speaking acts. These results suggest that emotion modulates linguistic processes not only in speech production but also in speech perception, and such modulations differ between the genders at least in perceptual processes.

Within-ear and across-ear interference in a dichotic cocktail party listening task: effects of masker uncertainty.

Increases in masker variability have been shown to increase the effects of informational masking in non-speech listening tasks, but relatively little is known about the influence that masker uncertainty has on the informational components of speech-on-speech masking. In this experiment, listeners were asked to extract information from a target phrase that was presented in their right ear while ignoring masking phrases that were presented in the same ear as the target phrase and in the ear opposite the target phrase. The level of masker uncertainty was varied by holding constant or "freezing" the talkers speaking the masking phrases, the semantic content used in the masking phrases, or both the talkers and the semantic content in the masking phrases within each block of 120 trials. The results showed that freezing the semantic content of the masking phrase in the target ear was the only reduction in masker uncertainty that ever resulted in a significant improvement in performance. Providing feedback after each trial improved performance overall, but did not prevent the listeners from making incorrect responses that matched the content of the frozen target-ear masking phrase. However, removing the target-ear contents corresponding to the masking phrase from the response set resulted in a dramatic improvement in performance. This suggests that the listeners were generally able to understand both of the phrases presented to the target ear, and that their incorrect responses in the task were almost entirely a result of their inability to determine which words were spoken by the target talker.

Effects of Spatial Intercoms and Active Noise Reduction Headsets on Speech Intelligibility in an AWACS Environment

An experiment was conducted aboard an E-3 Airborne Warning and Control System aircraft to assess the ability of spatial intercoms and active noise reduction (ANR) headsets to improve communications effectiveness for air battle managers. Eleven male participants completed four blocks of data collection using the Coordinate Response Measure under factorial combinations of spatialization, ANR, and target phrase location. Results indicate that the use of a spatial intercom led to greater intelligibility, and that ANR improved intelligibility only when used in combination with a spatial intercom. These results are discussed in terms of their applicability to current and future USAF application domains.

Predicting the directionality of probability words from their membership functions

AbstractTeigen and Brun have suggested that distinct from their numerical implications, most probability phrases are either positive or negative, in that they encourage one to think of reasons why the target event will or will not occur. We report two experiments testing our hypotheses that (a) the direction of a phrase can be predicted from properties of its membership function, and (b) this relation is invariant across contexts, and (c) —originally formulated by Teigen and Brun (1999)—that strong modifiers intensify phrase directionality. For each phrase, participants encoded membership functions by judging the degree to which it described the numerical probabilities 0.0, 0.1, …, 1.0, and also completed sentences including the target phrase. The types of reasons given in the sentence completion task were used to determine the phrase's directionality. The results support our hypotheses (a) and (b) regarding the relation between directionality and the membership functions, but we found only limited support for hypothesis (c) regarding the effects of modifiers on directionality. A secondary goal, to validate an efficient method of encoding membership functions, was also achieved. Copyright © 2003 John Wiley & Sons, Ltd.

A counterexample of spatial unmasking in multitalker speech perception

In listening tasks that involve more than one competing talker, substantial improvements in performance can usually be obtained by moving the target speech signal to a different location than the interfering speech signal. However, recent results in our laboratory suggest a possible listening configuration where informational and energetic masking effects might cause performance to decrease when an interfering speech signal is moved from the same ear as the target speech to the opposite ear. In this experiment, listeners were asked to respond to a color and number coordinate in a target phrase that was presented in two different listening configurations. In the first configuration, a high-level interfering talker and a low-level interfering talker were presented in the same ear as the target speech; in the second configuration, a high-level interfering talker was presented in the same ear as the target speech and a low-level interfering talker was presented in the ear opposite the target speech. The results confirm that the low-level interfering talker sometimes produced more interference when it was presented in a different ear than the target speech than when it was presented in the same ear.

The phonetics of stress clash in spontaneous speech

This study examines the rhythm rule (RR) in spontaneous speech to determine its acoustic correlates and phonetic robustness in conversational intonation. RR in English is a phonological process that accommodates stress clash. It has been primarily investigated in controlled speech. Both analyses of RR were considered in this study: (1) accent reversal—the relative prominence of key syllables is reversed, (2) accent deletion—the relative prominence of key syllables is neutralized. Two hypotheses were investigated: (1) RR is always indicated by measurable acoustic properties. (2) RR is subject to intonational factors and depends upon the attraction of a pitch accent for realization. Duration, f0, and amplitude were measured on relevant syllables. ToBI labeling was used to indicate pitch accents and phrase boundaries. Duration was the most consistent acoustic cue to stress clash resolution. When the target phrase attracted a pitch accent, duration indicated stress clash resolution by accent reversal. When the target phrase did not attract a pitch accent, f0 and duration indicated accent deletion. Crucially, when the phrases did not attract pitch accents (were not intonationally prominent), stress clash was resolved. This finding provides support for hypothesis (1): RR is pervasive in the acoustic signal independently of intonational factors.

Contralateral masking effects in dichotic listening with two competing talkers in the target ear

Some of the most influential experiments in selective auditory attention have been based on a dichotic cocktail party task where listeners are asked to respond to a speech signal presented to one ear while ignoring a simultaneous competing speech signal presented to the other ear. These experiments have generally shown that the intelligibility of a monaural speech signal is unimpeded by the presence of an interfering speech signal at the opposite ear. However, recent results in our laboratory indicate that listeners cannot ignore a speech signal at the unattended ear when two simultaneous speech signals are presented to the target ear. In this study, the intelligibility of a target phrase in a two-talker stimulus presented to one ear was measured monaurally and with a speech or noise signal in the opposite ear. Performance in this task was unaffected when noise was added to the unattended ear, but degraded substantially when speech was added to the unattended ear. These results suggest that there are strong interactions between the monaural processes that listeners use to segregate two spatially colocated voices and the binaural processes they use to segregate voices originating from different apparent locations in space. [Work supported by AFOSR.]

Increasing informational masking by contralateral stimulation

Although informational masking is thought to reflect central mechanisms, substantial reductions in informational masking generally occur when the target and masker are presented to different ears. Recently, Brungart and Simpson [J. Acoust. Soc. Am.] found that the intelligibility of a target phrase in a monaural two-talker stimulus was severely degraded by the addition of an unrelated speech signal to the contralateral ear. Their results suggest that the presence of an informational masker in the unattended ear can increase informational masking in the target ear. In this study parallel experiments using nonspeech informational maskers determined whether similar results are obtained in nonspeech detection tasks. The stimuli were sequences of multitone bursts arranged in spectrotemporal patterns that produce very large or very small amounts of informational masking. The signal was a sequence of 1000-Hz tone bursts played synchronously with the maskers. Combinations of effective and ineffective informational maskers were presented in the ear ipsilateral to and contralateral to the signal. Control conditions (masker ipsilateral/contralateral only) established baseline performance. The results supported the earlier findings for multiple-talker conditions. This suggests that the phenomenon is not restricted to speech and may reflect more general perceptual processes accessible through contralateral stimulation. [Supported by NIDCD and AFOSR.]

Informational and energetic masking effects in the perception of multiple simultaneous talkers

Although many researchers have examined the role that binaural cues play in the perception of spatially separated speech signals, relatively little is known about the cues that listeners use to segregate competing speech messages in a monaural or diotic stimulus. This series of experiments examined how variations in the relative levels and voice characteristics of the target and masking talkers influence a listener's ability to extract information from a target phrase in a 3-talker or 4-talker diotic stimulus. Performance in this speech perception task decreased systematically when the level of the target talker was reduced relative to the masking talkers. Performance also generally decreased when the target and masking talkers had similar voice characteristics: the target phrase was most intelligible when the target and masking phrases were spoken by different-sex talkers, and least intelligible when the target and masking phrases were spoken by the same talker. However, when the target-to-masker ratio was less than 3 dB, overall performance was usually lower with one different-sex masker than with all same-sex maskers. In most of the conditions tested, the listeners performed better when they were exposed to the characteristics of the target voice prior to the presentation of the stimulus. The results of these experiments demonstrate how monaural factors may play an important role in the segregation of speech signals in multitalker environments.

Informational and energetic masking effects in the perception of two simultaneous talkers.

Although most recent multitalker research has emphasized the importance of binaural cues, monaural cues can play an equally important role in the perception of multiple simultaneous speech signals. In this experiment, the intelligibility of a target phrase masked by a single competing masker phrase was measured as a function of signal-to-noise ratio (SNR) with same-talker, same-sex, and different-sex target and masker voices. The results indicate that informational masking, rather than energetic masking, dominated performance in this experiment. The amount of masking was highly dependent on the similarity of the target and masker voices: performance was best when different-sex talkers were used and worst when the same talker was used for target and masker. Performance did not, however, improve monotonically with increasing SNR. Intelligibility generally plateaued at SNRs below 0 dB and, in some cases, intensity differences between the target and masking voices produced substantial improvements in performance with decreasing SNR. The results indicate that informational and energetic masking play substantially different roles in the perception of competing speech messages.

Variable efficacy of rhythm and tone in melody-based interventions: Implications for the assumption of a right-hemisphere facilitation in non-fluent aphasia

This study examines the effects of tonal and rhythmic components of a melody-based intervention on the repetition abilities of two individuals with non-fluent aphasia. The subjects presented lesions restricted to the left hemisphere and showed moderate to severe limitations on repetition tasks. An alternate-treatment design was used where pre-recorded stimuli served to guide a therapist's production of models in treatment conditions emphasising the tonal or rhythmic attributes of target utterances. The results show that, relative to baseline performance, treatment emphasising the tonal attributes of target phrases had little or no impact on the subjects' immediate or deferred repetitions of the phrases. By comparison, exercises emphasising rhythm corresponded to substantial gains in the subjects' ability to repeat target utterances. Implications are drawn with respect to the rationale of melody-based therapies, specifically on the assumption that a right-hemisphere processing of tone may facilitate fluent speech.

Syntactic Influences on Lexical and Morphological Processing in Language Production

When one word replaces another in a speech error, the two words predominantly share syntactic category membership; this is the syntactic category constraint. Stem exchanges like “trucked the park” appear to violate this constraint, implying either that morphological representations do not include syntactic category information (e.g., Garrett, 1975) or that syntactic category membership only softly constrains lexical errors (Stemberger, 1985). Four experiments elicited exchanges with target phrases like “taped the record,” in which the intended nouns sound different when used as nouns (REcord) or as verbs (reCORD). With such phrases, a stem exchange reveals whether the word produced in verb stem position is a noun or verb. Against the predictions of standard accounts, in stem exchange errors, speakers predominantly produced phrases like “reCORDed the tape,” revealing that target nouns erroneously produced in verb stem position were produced as verbs. The pattern of results suggests that the processing of morphological representations is strongly influenced by syntactic information.

Modified Incidental Teaching Sessions

In this study, traditional incidental teaching was modified and a new naturalized parent training speech program, modified incidental teaching sessions (MITS), was designed. We then compared the efficacy of MITS with traditional incidental teaching and discrete trial. Using a multiple baseline design across and within children, with an alternating treatments design, we examined both the acquisition and, more importantly, generalization of target phrases for MITS as well as the comparison methods. Parents of three children with autism were trained to deliver MITS, traditional discrete trial, and incidental teaching in their home. Results indicated that MITS led to acquisition for all children, whereas only one child acquired the behavior with traditional incidental teaching, and two children acquired the behavior with discrete trial. Importantly, MITS also led to the generalization of target phrases, whereas no children generalized the target phrases with the incidental teaching and discrete trial conditions. These promising results are discussed in terms of maximizing the effectiveness of incidental teaching and the potential to provide naturalistic teaching strategies for parents that are associated with rapid and durable treatment gains.

Influences of length and syntactic complexity on the speech motor stability of the fluent speech of adults who stutter.

The purpose of the present study was to investigate the impact of utterance length and syntactic complexity on the speech motor stability of adults who stutter. Lower lip movement was recorded from 8 adults who stutter and 8 normally fluent controls. They produced a target phrase in isolation (baseline condition) and the same phrase embedded in utterances of increased length and/or increased syntactic complexity. The spatiotemporal index (STI) was used to quantify the stability of lower lip movements across multiple repetitions of the target phrase. Results indicated: (a) Adults who stutter demonstrated higher overall STI values than normally fluent adults across all experimental conditions, indicating decreased speech motor stability; (b) the speech motor stability of normally fluent adults was not affected by increasing syntactic complexity, but the speech motor stability of adults who stutter decreased when the stimuli were more complex; (c) increasing the length of the target utterance (without increasing syntactic complexity) did not affect the speech motor stability of either speaker group. These results indicate that language formulation processes may affect speech production processes and that the speech motor systems of adults who stutter may be especially susceptible to the linguistic demands required to produce a more complex utterance. The present findings, therefore, support the hypothesis that linguistic complexity is one factor that contributes to the disruptions of speech motor stability characteristic of stuttering.

Influences of utterance length and complexity on speech motor performance in children and adults.

The possible influences of utterance length and complexity on speech motor performance were examined by assessing the effects of increased processing demands on articulatory movement stability. Eight 5-year-old children and 8 young adults repeated a 6-syllable phrase in isolation (baseline condition) and embedded in sentences of low and high syntactic complexity. Lower lip movements for the target phrase were analyzed to produce the spatiotemporal index (STI), an index that reflects the stability of lip movement over 10 repetitions of the phrase. It was predicted that movement stability would be lower (reflected by higher values of the STI) for the phrase when it was spoken embedded in complex sentences and that, compared to adults, children's movement output would be more negatively affected by increased processing demands. The STI was significantly increased for the phrase spoken in the complex sentences compared to the baseline condition, and STIs of the children were consistently higher than those of the adults across conditions. These findings provide novel evidence that speech motor planning, execution, or both are affected by processes often considered to be relatively remote from the motor output stage.

The effect of sentence onset asynchrony on call sign detection and message intelligibility in a simulated ‘‘cocktail party’’

Previous research has demonstrated that the spatial separation of multiple simultaneous talkers improves detection and intelligibility of a critical speech signal among non-signal speech events [Nelson et al., J. Acoust. Soc. Am. 103, 2341–2342(A) (1998); M. L. Hawley et al., J. Acoust. Soc. Am. 99, 2596(A) (1996)]. However, few findings on the effects of varying phrase onsets have been reported [J. C. Webster and P. O. Thompson, J. Acoust. Soc. Am. 26, 396–402 (1954)]. The purpose of the present study was to investigate the effect of varying the interval between sentence onsets on call sign detection and message intelligibility. The relative onset times of two to eight temporally overlapping phrases were varied systematically in both spatially separated and nonspatially separated conditions on the horizontal plane. The phrases were presented virtually to five normal-hearing listeners. All possible temporal positions of the target phrase were examined. Results will be discussed in the context of listening to speech in real-world situations. [Work supported by AFOSR.]

The Development of Fundamental Frequency in 6- to 10-Year Old Children: A Brief Study

This brief study investigates the development of fundamental frequency (FO) in pre-adolescent children as a function of age and sex. The children who took part in the study were divided into three age groups: 6, 8 and 10 years. Each group consisted of three males and three females. Each subject produced nine target phrases with [] in phrase-final position, which were elicited via a picture-naming task. FO was estimated for the nine target utterances and the following FO parameters were derived: mean FO for the whole phrase; FO range for the whole phrase; standard deviation values of FO for the whole phrase and mean FO for the phrase-final vowel [α:]. Results indicated that FO parameters generally decreased with age, and by age 10 years the males had lower values than the females for all four parameters. Results also indicated that the mean standard deviation of FO across the phrase was significantly higher for the females compared to that for the males.

The domain of phrase-final lengthening in English

Intonational phrase final lengthening is well established for the final syllable rhyme in English [Klatt (1976), Wightman (1992), Campbell and Isard (1991)]; there is some evidence for lengthening extending further leftward [Langeveld (1997) for Dutch, Berkowitz (1993) for Hebrew], and for post-boundary lengthening of the initial consonant of a new prosodic constituent [Fougeron and Keating (1997), Fougeron (1997), Gow and Gordon (1995), and A. Cooper (1991)]. It is asked whether boundary-related duration lengthening extends further in both directions from a prosodic constituent boundary, using prosodically disambiguated sentence pairs like ‘‘Please say ‘Thomasburg or Terraceville and Watertown will play’ ’’ and ‘‘Please say ‘Michigan or Madison and Vatican will play,’ ’’ in which pitch-accent and main-word-stress-related lengthening can be distinguished from boundary-related lengthening. Results will be presented for 40 sentence pairs produced by four speakers (normal and reiterant forms) for individual time segments measured across the full extent of each target phrase. Preliminary results from a single speaker suggest that preboundary lengthening can extend leftward to the primary stress of a polysyllabic word. [Work supported by EPSRC.]