José R. Benkí

Quantitative evaluation of lexical status, word frequency, and neighborhood density as context effects in spoken word recognition

Listeners identified a phonetically balanced set of consonant-vowel-consonant (CVC) words and nonsense syllables in noise at four signal-to-noise ratios. The identification scores for phonemes and syllables were analyzed using the j-factor model [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101-114 (1988)], which measures the perceptual independence of the parts of a whole. Results indicate that nonsense CVC syllables are perceived as having three independent phonemes, while words show j = 2.34 independent units. Among the words, high-frequency words are perceived as having significantly fewer independent units than low-frequency words. Words with dense phonetic neighborhoods are perceived as having 0.5 more independent units than words with sparse neighborhoods. The neighborhood effect in these data is due almost entirely to density as determined by the initial consonant and vowel, demonstrated in analyses by subjects and items, and correlation analyses of syllable recognition with the neighborhood activation model [Luce and Pisoni, Ear Hear. 19, 1-36 (1998)]. The j factors are interpreted as measuring increased efficiency of the perception of word-final consonants of words in sparse neighborhoods during spoken word recognition.

Effects of training procedures and vowel set on learning non‐native vowel categories

Results of four new experiments are reported which examine American English listeners’ perception of German front rounded vowels. They differ from previous experiments [Kingston et al., J. Acoust. Soc. Am. 99, 2602–2603(A) (1996)] in that listeners were trained with classification of all two‐stimulus subsets of four‐member sets of German vowels as well as with the complete four‐stimulus identification task used by Logan et al. [J. Acoust. Soc. Am. 89, 874–876 (1991)] in training. Despite the addition of these easier tasks, as in the previous experiments, both learning and generalization were modest in the four new experiments. One new experiment replicated the result obtained earlier with the front rounded vowel set, /y,Y,o/,œ/, whose members contrast for [tense] and [high]: that any contrast involving mid lax /œ/ is particularly easy. Two other experiments examined the lax front vowels contrasting for [high] and [round], /i,Y,e,œ/; both found correlated feature contrasts to be easier than single feature ...

Context effects in recognition of English disyllabic word and nonwords by native and non‐native listeners

Thirty‐two native (L1=German) and 30 non‐native (L1=English) listeners heard German CVCCVC words and nonwords mixed with noise. Of the words, half were monomorphemic and half bimorphemic. The j‐factor model [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101–114 (1988)] was used as a measure of lexical context effects. For both native and non‐native speakers, words showed greater context effects than nonwords, though the difference was not as large for non‐native speakers. Monomorphemic words also exhibited greater context effects than bimorphemic words, again with a larger effect for native speakers. For both native and non‐native listeners, neighborhood density had a significant effect, although the amount of variation explained was much less for non‐native listeners. This is interpreted to be a result of the smaller lexicon of the non‐native listeners. Misperceptions between native and non‐native speakers were also compared, with non‐native speakers showing patterns predictable by phonological differ...

Recognition of English phonemes in noise

Native speakers of American English identified the consonants and vowels of American English CV and VC syllables and the vowels of hVd syllables. The CV and VC syllables, consisting of all of the English consonant phonemes, were selected from recordings described by Shannon et al. [J. Acoust. Soc. Am. 106, L71–L74 (1999)], and the hVd syllables were selected from recordings described by Hillenbrand et al. [J. Acoust. Soc. Am. 97, 3623–3641 (1995)]. All syllables were presented binaurally in signal‐correlated noise. The resulting confusion matrices and feature analyses will be presented along with a position (initial versus final) analysis for the consonant results. The consonant and vowel results will be used to derive empirical measures of similarity of English words. [Work supported by NIH/NIDCD.]

Effects of blocking and presentation on the recognition of word and nonsense syllables in noise

Listener expectations may have significant effects on spoken word recognition, modulating word similarity effects from the lexicon. This study investigates the effect of blocking by lexical status on the recognition of word and nonsense syllables in noise. 240 phonemically matched word and nonsense CVC syllables [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101–108 (1988)] were presented to listeners at different S/N ratios for identification. In the mixed condition, listeners were presented with blocks containing both words and nonwords, while listeners in the blocked condition were presented with the trials in blocks containing either words or nonwords. The targets were presented in isolation with 50 ms of preceding and following noise. Preliminary results indicate no effect of blocking on accuracy for either word or nonsense syllables; results from neighborhood density analyses will be presented. Consistent with previous studies, a j‐factor analysis indicates that words are perceived as containing ...

Recognition of word and nonsense syllables in noise

In the recognition of human speech, listeners use sensory information from the speech signal as well as signal‐independent information, such that acoustic‐phonetic salience, lexical status, frequency of usage, and neighborhood density interact in speech recognition. This paper presents detailed results from a replication of a study of context effects reported by Boothroyd and Nittrouer [J. Acoust. Soc. Am. 84, 101–108 (1988)]. 240 phonetically matched word and nonsense CVC syllables at different SNRs were presented to 32 listeners for identification. The results are consistent with the original study, with greater accuracy for words than nonsense items as quantified by a j‐factor analysis according to lexical status. Online response collection enabled detailed analyses not reported in the original study. Values for the j‐factor according to usage frequency and phonetic confusability are presented. Confusion matrices of the phonemes are presented, and are largely consistent with previous studies for the in...

The importance of lexical status in word recognition of familiar words and novel items

Talker variability and its effects on speech perception is an issue of central importance in word recognition research, and it is known that familiarity with a speaker’s voice improves recognition of novel words [Nygaard et al., Psych. Sci. 5, 42–46 (1994)]. In an investigation of how talker variability interacts with lexical status in the recognition of both familiar and unfamiliar words, listeners performed a closed‐set identification task. A visual prime of four potential responses consisting of words and nonsense words that differed minimally phonologically was presented, followed by the audio target stimulus for identification using a response box. The experiment consisted of three 100‐trial blocks. The trials were blocked according to talker variability (first block, single talker; second block, multiple talkers; and third block, single talker). Lexical status of the target stimulus varied within trials. Response times were also collected. Listeners performed better when the target item was a word i...

Effects of first formant onset properties on voicing judgments of prevocalic stops without F1 cutback

This study examines the effects of first formant (F1) onset properties on voicing judgments of prevocalic stop consonants in contexts that do not exhibit the F1 cutback covariation present in pretonic and utterance‐initial voicing contrasts. Previous research [K. R. Kluender and A. J. Lotto, J. Acoust. Soc. Am. 95, 1044–1052 (1994)] strongly suggests that F1 onset frequency effects on voicing judgements are due to auditory factors, and not to listener experience with natural covariance with F1 cutback and F1 onset frequency. The present study extends the previous findings to voicing contrasts in contexts that are not signaled by F1 cutback, such as before unstressed vowels in English. Categorization data were collected for a continuum between rabid (/b/) and rapid (/p/) in which both closure duration and F1 onset properties were manipulated using LPC resynthesis of natural speech. Preliminary results indicate that lower F1 onset frequencies of the unstressed vowel condition more voiced percepts of the pre...

Perceptual interactions among voice onset time, second formant onset, voice, and place of articulation

The categorization of voicing in syllable‐initial stops is dependent primarily on voice onset time (VOT), while the categorization of place of articulation (POA) in stops is dependent primarily on higher formant transitions. This study tested for perceptual interactions among these two orthogonal acoustic dimensions (VOT and higher‐formant transitions) and the corresponding phonological contrasts of voice and POA. Fifteen subjects categorized initial stops in a /Ca/ context as /ba/, /pa/, /ga/, or /ka/. The initial stop of each token was from a synthetic two‐dimensional continuum with acoustic dimensions of VOT (0–45 ms) and second formant (F2) onset frequency (1100–1700 Hz), so that the corners of the continuum were unambiguous /ba/, /pa/, /ga/, and /ka/. A model of POA and voicing categorization derived from logistic regression suggests that the VOT category boundary can change depending on the perceived POA. Tokens categorized as bilabial were more likely than those perceived as velars to be also categ...

Effects of place of articulation and first formant onset properties on voicing judgments

The categorization of voiced and voiceless syllable‐initial stops is dependent primarily on voice onset time (VOT), but has been proposed to be sensitive to first formant (F1) transitions and place of articulation. The present study tested the effect of both F1 transition and place cues on the categorization of voiced and voiceless stops in a /■Ca/ context (second syllable stress). Three different stop properties were independently manipulated: VOT, F1 onset frequency, and place of articulation. VOT was varied along a 0 to 65‐ms continuum. Four different F1 onset frequencies for the /Ca/ transition were used. Place (labial, alveolar, and velar) was cued by both the release burst and higher formant transitions into and out of the stop. The effects of F1 transition and place on voicing judgments were measured by shifts in the VOT identification boundary. The effect of F1 on voicing judgments would be interpreted as resulting from a general mechanism of audition nonspecific to speech, following Kluender [J. ...