Biomedical subjects

J Jakimik

Publications and source records attributed to J Jakimik.

3 recordsLinked to original sources

PubMed1980

How are syllables used to recognize words?

Our subjects were instructed to push a response button as quickly as possible whenever they detected a mispronounced word in a story. Mispronunciations were produced by changing a syllable-initial /p/ or /k/ to its voiced counterpart (/b/ or /g/). The syllable stress and syllable position (first versus second) of the mispronunciation were varied in a 2 x 2 design. As expected on acoustic grounds, mispronunciations were detected more often in stressed than unstressed syllables. However, reaction times to mispronunciations in both stressed and unstressed syllables were about 200-ms faster in the second syllable of a word. The finding of faster reaction times to second syllables is consistent with the assumption that words are accessed from the sounds which begin them.

Adult↗

PubMed1980

Segmenting speech into words.

Four experiments employed a listening for mispronuciations task to determine how listeners perceive an ordered series of words from a continuous, phonetically ambiguous stimulus. In experiments 1,2, and 3, listeners' reaction times to detect mispronuciations were obtained in phonological sequences that could be perceived as either one or two words (e.g., "cargo" or "car go" mispronounced "carko"). In experiment 1, segmentation of the acoustic signal as one or two words was guided by the theme of a short story. For example, the sentence "They saw the carko on the ferry" was spliced into two stories--one about a shipment of cargo, and one about a car about to go on a ferryboat. The results showed significantly faster reaction times--by about 300 ms--when the mispronunciation was perceived as occurring in the second syllable of a word. In experiment 2, alternate segmentation of the same acoustic signal were constrained by the grammatical nature of the first few words in a sentence. Subjects were presented with sentences such as "The doctor said that nosetrops will help the cold" or "the doctor said he knows trops will help the cold." By means of tape splicing, the final portions of the two sentences in each pair were acoustically identical. Reaction times were again found to be faster--by about 150 ms--when the mispronunciation was perceived as occuring in the second or third syllable of a word, rather than at the beginning of a word. Experiment 3 replicated these results using naturally recorded sentences having normal prosody. The results of experiments 1-3 demonstrated that prior context determines how syllables are recognized as words and that a mispronounced second syllable is detected faster than a mispronounced word-initial syllable. It was argued that mispronunciations are detected more quickly in second syllables because the intended word has been accessed from its first syllable. This hypothesis was further supported in experiment 4. When subjects read each sentence before hearing it, so that all syllables were equally (and perfectly) predictable, mispronunications were detected equally fast in first and second syllables.

Humans↗

PubMed1978

Perceptibility of phonetic features in fluent speech.

A series of experiments examined listeners' ability to detect mispronounced words in a short story. Mispronunciations were produced by changing a single consonant segment in a word to produce a (phonologically permissible) nonsense word. The results of six different experiments showed that prestressed work-initial stop consonants are more perceptible than other consonants. For example, mispronunciations produced by changing the voicing of a word-initial stop (e.g., "boy" to "poy") were detected about 70% of the time, while changes in voicing of a word-initial fricative (e.g., "voice" to "foice") were detected about 38% of the time. Mispronunciations produced by changing the place of articulation of a prestressed word-initial stop were most detectable of all (80% to 90% detection) for three different speakers. A change in place of articulation of a word-initial stop (e.g., "baby" to "daby") was detected as often as a change in both place of articulation and voicing (e.g., "baby" to "taby"). Finally, it was found that a mispronunciation was detected about twice as often in word-initial than in word-final position in one syllable words for both stops and nasals. The results suggest that listeners pay special attention to word-initial stop consonants in natural continuous speech.

Humans↗