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.