Biomedical subjects

H M Saldaña

Publications and source records attributed to H M Saldaña.

7 recordsLinked to original sources

PubMed1996

An audiovisual test of kinematic primitives for visual speech perception.

Isolated kinematic properties of visible speech can provide information for lip reading. Kinematic facial information is isolated by darkening an actor's face and attaching dots to various articulators so that only moving dots can be seen with no facial features present. To test the salience of these images, the authors conducted experiments to determine whether the images could visually influence the perception of discrepant auditory syllables. Results showed that these images can influence auditory speech independently of the participant's knowledge of the stimuli. In other experiments, single frozen frames of visible syllables were presented with discrepant auditory syllables to test the salience of static facial features. Although the influence of the kinematic stimuli was perceptual, any influence of the static featural stimuli was likely based on participant's misunderstanding or postperceptual response bias.

Adult↗

PubMed1996

Point-light facial displays enhance comprehension of speech in noise.

Seeing a talker's face can improve the perception of speech in noise. There is little known about which characteristics of the face are useful for enhancing the degraded signal. In this study, a point-light technique was employed to help isolate the salient kinematic aspects of a visible articulating face. In this technique, fluorescent dots were arranged on the lips, teeth, tongue, cheeks, and jaw of an actor. The actor was videotaped speaking in the dark, so that when shown to observers, only the moving dots were seen. To test whether these reduced images could contribute to the perception of degraded speech, noise-embedded sentences were dubbed with the point-light images at various signal-to-noise ratios. It was found that these images could significantly improve comprehension for adults with normal hearing and that the images became more effective as participants gained experience with the stimuli. These results have implications for uncovering salient visual speech information as well as in the development of telecommunication systems for listeners who are hearing impaired.

Adolescent↗

PubMed1994

Selective adaptation in speech perception using a compelling audiovisual adaptor.

A replication of the audiovisual test of speech selective adaptation performed by Roberts and Summerfield [Percept. Psychophys. 30, 309-314 (1981)] was conducted. The audiovisual methodology allows for the dissociation of acoustic and phonetic components of an adapting stimulus. Roberts and Summerfield's results have been interpreted to support an auditory basis for selective adaptation. However, their subjects did not consistently report hearing the adaptor as a visually influenced syllable making this interpretation questionable. In the present experiment, a more compelling audiovisual adaptor was implemented resulting in a visually influenced percept 99% of the time. Still, systematic adaptation occurred only for the auditory component.

Acoustic Stimulation↗

PubMed1993

Dynamical constraints on pictorial action lines.

Pictorial action lines are an effective way of portraying movement in a static drawing. When such lines emanate from the backs of characters, they can give a sense of the path or style of movement. Seven experiments assessed whether photographic streak lines-lines that depict actual movement paths-can, in and of themselves, be informative about the act that produced them. Lines were produced as a darkly clad actor with point-lights attached to his major joints performed a number of actions in front of an open-lens camera. Completely naive Ss had little success identifying events in these photographs. Once Ss were told of the photographic technique, however, striking proficiency was achieved. Subtle distinctions (e.g., whether the movement was forward or backward or performed while wearing weights) were made for some of the events. Results are discussed in terms of various treatments of pictorial information.

Adult↗

PubMed1993

Auditory looming perception: influences on anticipatory judgments.

Several studies in the auditory-perception literature hint that listeners may be able to anticipate the time of arrival of an approaching sound source. Two experiments are reported in which listeners judged the time of arrival of an approaching car on the basis of various portions of its auditory signal. Subjects pressed a computer key to indicate when the car would have just passed them, assuming that the car maintained a constant approach velocity. A number of variables were tested including (a) the time between the offset of the signal and the virtual time of passage, (b) duration of the signal, and (c) feedback concerning judgment accuracy. Results indicate that increasing the time between signal offset and virtual time of passage decreases judgment accuracy whereas the actual duration of the signal had no significant effect. Feedback significantly improved performance overall.

Adult↗

PubMed1993

Visual influences on auditory pluck and bow judgments.

In the McGurk effect, visual information specifying a speaker's articulatory movements can influence auditory judgments of speech. In the present study, we attempted to find an analogue of the McGurk effect by using nonspeech stimuli--the discrepant audiovisual tokens of plucks and bows on a cello. The results of an initial experiment revealed that subjects' auditory judgments were influenced significantly by the visual pluck and bow stimuli. However, a second experiment in which speech syllables were used demonstrated that the visual influence on consonants was significantly greater than the visual influence observed for pluck-bow stimuli. This result could be interpreted to suggest that the nonspeech visual influence was not a true McGurk effect. In a third experiment, visual stimuli consisting of the words pluck and bow were found to have no influence over auditory pluck and bow judgments. This result could suggest that the nonspeech effects found in Experiment 1 were based on the audio and visual information's having an ostensive lawful relation to the specified event. These results are discussed in terms of motor-theory, ecological, and FLMP approaches to speech perception.

Acoustic Stimulation↗

PubMed1992

Discrimination tests of visually influenced syllables.

In the McGurk effect, perception of audiovisually discrepant syllables can depend on auditory, visual, or a combination of audiovisual information. Under some conditions, visual information can override auditory information to the extent that identification judgments of a visually influenced syllable can be as consistent as for an analogous audiovisually compatible syllable. This might indicate that visually influenced and analogous audiovisually compatible syllables are phonetically equivalent. Experiments were designed to test this issue using a compelling visually influenced syllable in an AXB matching paradigm. Subjects were asked to match an audio syllable/va/either to an audiovisually consistent syllable (audio/va/-video/fa/) or an audiovisually discrepant syllable (audio/ba/-video/fa/). It was hypothesized that if the two audiovisual syllables were phonetically equivalent, then subjects should choose them equally often in the matching task. Results show, however, that subjects are more likely to match the audio/va/ to the audiovisually consistent/va/, suggesting differences in phonetic convincingness. Additional experiments further suggest that this preference is not based on a phonetically extraneous dimension or on noticeable relative audiovisual discrepancies.

Adult↗