Ronald A. Cole

Listening for mispronunciations: A measure of what we hear during speech

Ss heard a passage from Lewis Carroll’s Through the Looking Glass and were asked to indicate, as quickly as possible, whenever they heard a mispronunciation. Mispronunciations were produced by changing one consonant sound in a three-syllable word by one, two, or four distinctive features (e.g., busily to “pizily,” “visily,” or “sizily”). Mispronunciations involving a single feature change were seldom detected, while two and four feature changes were readily detected. The syllable in which a mispronunciation occurred did not affect the probability of detecting a mispronunciation. However, reaction times to mispronounced words were at least a third of a second slower when they occurred in the-first syllable of the word. The results were taken to support the notion that words are identified by their distinctive features.

Memory of a speaker's voice: Reaction time to same- or different-voiced letters

Subjects were presented with a sequence of two letters, each letter spoken in either a male or female voice. On each trial, the subject was required to indicate, as quickly as possible, whether the two letters had the same name. Reaction times (RTs) were faster for letters spoken in the same voice for both “same” and “different” responses, even when letters were separated by 8 s. These results are incompatible with the notion of physical and name codes in auditory memory since a “different” response should always be based on a comparison of letter names and should not be influenced by voice quality. It was also found that RTs were not influenced by the phonemic distinctive feature similarity of the letters.

The phantom in the phoneme: Invariant cues for stop consonants

The stop consonants /b, d, g, p, t, k/were recorded before/i/,/a/,/u/. The energy spectrum for each stop consonant was removed from its original vowel and spliced onto a different steady-state vowel. Results of a recognition test revealed that consonants were accurately recognized in all cases except when /k/ or/g[ was spliced from/i/to/u/. Further demonstrations suggested that/k/ and /g/ do have invariant characteristics before/i/, /a/, and /u/. These results support the general notion that stop consonants may be recognized before different vowels in normal speech in terms of invariant acoustic features.

Different memory functions for consonants and vowels

Abstract Different memory functions were obtained for consonants (C) and vowels (V) in a serial recall task. In general, the most recently heard vowels in a sequence were easier to recall than the most recently heard consonants. This effect was observed for auditorily presented sequences of CV or VC syllables, but was not observed for visually presented stimuli. The results were explained in terms of a limited capacity acoustic storage in which vowels are preserved longer than consonants. Retrieval of the last vowels from this storage was presumed to cause the vowel recency effect.

Distinctive feature control of decision time: Same-different judgments of simultaneously heard phonemes

Ss decided whether dichotically presented consonant or vowel phonemes were “same” or “different” in a reaction time (RT) task. Results indicated that “different” responses were made on the basis of a serial, self-terminating scan of distinctive feature differences between phonemes. “Same” responses were considered too fast to be accounted for by this process and were discussed as a separate parallel process. Recognition of dichotically presented syllables appears to involve a third process in which phonemes are also identified in terms of their distinctive features.

Mechanisms of aural encoding: VI. Consonants and vowels are remembered as subsets of distinctive features

An attempt was made to examine the manner in which consonants and vowels are coded in short-term memory. under identical recall conditions. Ss were presented with sequences of consonant-vowel digrams for serial recall. Sequences were composed of randomly presented consonants paired with/a/ or randomly presented vowels paired with /d/. Halle’s distinctive feature system was used to generate predictions concerning the frequency of intrusion errors. among phonemes. These predictions were based on the assumption that phonemes are discriminated in memory in terms of their component distinctive features, so that intrusions should most frequently occur between phonemes sharing similar distinctive features. The analysis of intrusion errors revealed that each consonant and vowel phoneme was coded m short-term memory by a particular combination of distinctive features which differed from one phoneme to another. A given phoneme was coded by the same set of distinctive features regardless of the number of syllables in the sequence. However, distinctive feature theories were not able to predict the frequency of intrusion errors for phonemes presented in the middle serial positions of a sequence with 100% accuracy. The results of the experiment support the notion that consonant and vowel phonemes are coded in a similar manner in STM and that this coding involves the retention of a specific set of distinctive features for each phoneme.

Mechanisms of aural encoding: VIII. Phonetic interference and context-sensitive coding in short-term memory.

In previous experiments Ss were presented for ordered recall with sequences of five consonant phonemes paired with /a/ in which the middle three consonant phonemes shared the same manner of articulation (voiced, unvoiced, nasal), the same place of articulation (front, middle, back), or neither the same manner nor place of articulation (control sequences). Compared to performance in control sequences, the middle consonant phoneme was always more difficult to recall in manner of articulation sequences but not in place of articulation sequences. The results suggested that for these sequences consonant phonemes were not remembered in terms of their place of articulation. In the present experiment, sequences of consonant-vowel (CV) or vowel-consonant (VC) syllables were presented for recall in which each consonant phoneme was paired with a different vowel. When consonant phonemes in the different sequence types were presented for recall with different vowels, phonetic interference was observed for the middle consonant in place of articulation sequences as well as manner of articulation sequences, and the effect was observed in both CV and VC groups. It was suggested that vowels are encoded in short-term memory in terms of their place of articulation and that presenting consonant phonemes for recall with different vowels caused Ss to use this dimension to code consonant phonemes in short-term memory.

Mechanisms of aural encoding: VII. Differences in consonant and vowel recall in a Peterson and Peterson short-term memory paradigm

Ss either saw or heard lists of three syllables which differed by their initial consonant phoneme or their final vowel phoneme. After 5 or 15 sec of mental arithmetic, Ss were required to recall the syllables. Following auditory presentation, vowels were recalled more accurately than consonants in all serial positions and at both delays. In addition, spoken consonants and vowels showed primacy and recency effects. Following visual presentation, consonants and vowels were recalled with equal accuracy at both delays, and no recency effects were observed. These data suggest that superior recall of vowels over consonants results from differential decay of these stimuli in an acoustic storage. These data are consistent with previous experiments showing that, during serial recall, the final vowels in a sequence are recalled more accurately than the final consonants.