Biomedical subjects

Liat Kishon-Rabin

Publications and source records attributed to Liat Kishon-Rabin.

25 records · Page 2Linked to original sources

PubMed2003

Effect of voice onset time (VOT), stop burst and vowel on the perception of voicing in Hebrew stops: preliminary results.

Very few studies investigated systematically the acoustic cues for the perception of voicing stops in Hebrew. Voicing is characterized by several parameters of which the voice onset time (VOT) was found to be the primary cue for its perception. There are, however, other known acoustic cues to voicing such as transition to the first formant (F1) and the initial burst. The purpose of the present study was to measure the relative weighting of these various acoustic cues in the perception of Hebrew voicing, using the conflicting cues paradigm. Thirteen adults with normal hearing participated in this study. Stimuli consisted of one pair of meaningful words that differ in the voicing of the initial stop. Four different continua were constructed from the pair of natural stimuli. The first two consisted of the voiced burst combined with the vowel that was truncated from the consonant-vowel combination (where the consonant was voiced or voiceless). The remaining two continua consisted of the voiceless burst combined with the same truncated vowels. For each stimulus, a VOT continuum was created varying from -40 to +40 ms in 10 ms segments. Subjects were tested using a two alternative forced choice labeling procedure. The percent of responses to each stimulus of each VOT continuum (/b-p/) was calculated for each individual and combination. The results show that each acoustic cue contributed to the perception of initial voicing in Hebrew: (1) When the stimulus was constructed from the voiced cues, positive VOT values were needed for the voice/voiceless distinction; (2) when the stimulus was constructed from the voiceless cues, negative VOT values were needed for the voicing distinction; and (3) when the stimulus was constructed from voiced and voiceless cues, intermediate VOT values were needed for the voicing distinction. These results provide initial information regarding the relative effect of the acoustic cues in the perception of Hebrew stop voicing.

Acoustic Stimulation↗

PubMed2002

The effect of oral contraceptives on voice: preliminary observations.

Most studies investigating the effect of sex hormones on the larynx and vocal folds focused on the voice quality of women either around menopause or during the menstrual cycle. To our knowledge, however, there have been no studies that investigated the effect of oral contraceptives on the female voice. In the present study five women who ingest oral contraceptives (pill group) and five women who do not (natural group) were recorded producing the vowels /i/ and /a/ repeatedly over a period of 40 days. Acoustic analyses were performed on these recordings including F0, amplitude, jitter, shimmer, and harmonic-to-noise ratio (HNR). Results indicated that jitter and shimmer values of the pill group were significantly lower than those of the natural group. No group differences were found for F0, amplitude, or HNR. In addition, the pill group demonstrated significantly smaller variance for all variables tested. The results suggest that oral contraceptives might increase voice stability associated with smaller hormonal changes. Thus the present study provides preliminary evidence of the effect of oral contraceptives on the female voice.

Adult↗

PubMed2002

Development of speech perception and production in children with cochlear implants.

The purpose of the present study was twofold: 1) to compare the hierarchy of perceived and produced significant speech pattern contrasts in children with cochlear implants, and 2) to compare this hierarchy to developmental data of children with normal hearing. The subjects included 35 prelingual hearing-impaired children with multichannel cochlear implants. The test materials were the Hebrew Speech Pattern Contrast (HeSPAC) test and the Hebrew Picture Speech Pattern Contrast (HePiSPAC) test for older and younger children, respectively. The results show that 1) auditory speech perception performance of children with cochlear implants reaches an asymptote at 76% (after correction for guessing) between 4 and 6 years of implant use; 2) all implant users perceived vowel place extremely well immediately after implantation; 3) most implanted children perceived initial voicing at chance level until 2 to 3 years after implantation, after which scores improved by 60% to 70% with implant use; 4) the hierarchy of phonetic-feature production paralleled that of perception: vowels first, voicing last, and manner and place of articulation in between; and 5) the hierarchy in speech pattern contrast perception and production was similar between the implanted and the normal-hearing children, with the exception of the vowels (possibly because of the interaction between the specific information provided by the implant device and the acoustics of the Hebrew language). The data reported here contribute to our current knowledge about the development of phonological contrasts in children who were deprived of sound in the first few years of their lives and then developed phonetic representations via cochlear implants. The data also provide additional insight into the interrelated skills of speech perception and production.

Age Factors↗

PubMed2002

Auditory backward masking in normal hearing children.

Backward masking (BM) is an auditory phenomenon in which the threshold of an auditory signal is elevated due to the presence of another signal (masker) that follows it. Models related to central auditory temporal processes, such as the 'temporal window' model, have been suggested to explain this phenomenon. If this assumption is correct then BM thresholds are expected to improve as a function of age. Electrophysiological data suggest that the central auditory system undergoes maturation in the first two decades of life. Empirical data on the development of BM with age are limited. Therefore, the goals of the present study were to study the effect of age on the performance of backward masking in normal developing children and to determine the age at which children reach adult-like performance. Subjects were 30 normal developing children divided into three groups according to age: 7, 9 and 11 years old. Stimuli consisted of a 1000 Hz pure tone and a bandpass masker (600-1400 Hz). Three BM threshold estimates were obtained for each subject using a three-alternative forced-choice adaptive procedure. The data show a trend for improvement in backward-masking thresholds with increasing age. Specifically, 7 and 9 year-old children performed significantly poorer than those reported for adults, whereas 11 year-old children reached adult-like performance. These data contribute to the small body of literature on backward masking in normal developing children. They are in keeping with what is known regarding the age of physiological maturation of the auditory system and have important clinical implications in the assessment of children with suspected temporal processing deficits.

Acoustic Stimulation↗

PubMed2002

Underlying mechanism for categorical perception: tone-onset time and voice-onset time evidence of Hebrew voicing.

The nature of the mechanism responsible for the categorical labeling of stimuli is not clear. One hypothesis suggests that categorization is limited by the 'natural sensitivities' of the auditory system. The alternative hypothesis suggests that categorization is mediated by a special speech mode and is influenced by how speech is produced. The present study attempts to provide some insight into this dilemma by evaluating categorical perception (CP) in speech and non-speech stimuli and across languages. Specifically, the goals of the present study were (1) to compare phonetic boundaries of Hebrew voicing to categorical boundaries (CB) of a two-tone complex which varies in the relative timing of the two tones (TOT) [TOT stimuli are considered be the non-speech analog to voice-onset time (VOT)], and (2) to re-establish the CB values of non-speech analog to voicing in American-English speakers using the same TOT continua as the Hebrew speakers and to compare them to CB of Hebrew-speaking subjects. Our assumption was that if CP is mediated by basic auditory sensitivity then we expect similar CB for speech and non-speech stimuli and no effect of language on CB. If, however, a special speech code determines CP, then phonetic boundaries are expected to be different from CB of non-speech stimuli and across languages. Of particular interest is the special case of Hebrew whose voice-voiceless distinction in production is very different from that in English. Twelve Hebrew-speaking adults and 12 American-English speaking adults participated in this study. Stimuli consisted of (a) a two-tone complex continuum that varied in the relative onset time of the lower tone from a lead of -100 ms to a lag of +50 ms in 10 ms steps, and (b) a /ba-pa/ continuum which varied in VOT values similar to (a). Subjects identified TOT stimuli as belonging to one of three categories: leading, simultaneous, or lagging. VOT stimuli were labeled as /ba/ or /pa/. Results show (a) different phonetic boundary for Hebrew voicing compared to published data on English voicing, (b) different category boundaries for speech and non-speech stimuli in Hebrew, (c) a phonetic boundary for Hebrew voicing that does not align with the VOT values of production, and (d) very similar CB for TOT stimuli in Hebrew- and American-English-speaking subjects. The data support the influence of both general auditory abilities and unique speech processes on categorical perception of speech.

Acoustic Stimulation↗

PubMedDate not supplied

A latent consolidation phase in auditory identification learning: time in the awake state is sufficient.

Large gains in performance, evolving hours after practice has terminated, were reported in a number of visual and some motor learning tasks, as well as recently in an auditory nonverbal discrimination task. It was proposed that these gains reflect a latent phase of experience-triggered memory consolidation in human skill learning. It is not clear, however, whether and when delayed gains in performance evolve following training in an auditory verbal identification task. Here we show that normal-hearing young adults trained to identify consonant-vowel stimuli in increasing levels of background noise showed significant, robust, delayed gains in performance that became effective not earlier than 4 h post-training, with most participants improving at more than 6 h post-training. These gains were retained for over 6 mo. Moreover, although it has been recently argued that time including sleep, rather than time per se, is necessary for the evolution of delayed gains in human perceptual learning, our results show that 12 h post-training in the waking state were as effective as 12 h, including no less than 6 h night's sleep. Altogether, the results indicate, for the first time, the existence of a latent, hours-long, consolidation phase in a human auditory verbal learning task, which occurs even during the awake state.

Adult↗

PubMedDate not supplied

Auditory event-related potentials during phonetic and semantic processing in children.

This study was designed to follow the time course of different levels of linguistic processing using auditory event-related potentials (AERPs). A hierarchical set of acoustically controlled stimuli was used to elicit AERPs in 20 normal children who performed discrimination tasks involving pure tones, phonetic 'easy' and 'difficult' stimuli and semantic stimuli. Results show that (1) AERP latencies were similar for phonetic 'easy' and 'difficult' stimuli, (2) prolonged P(2), N(2) and P(3) latencies characterized semantic processing compared to phonetic processing, (3) a late negativity was elicited during semantic processing only, (4) P(3) amplitudes were larger over the left compared to right scalp during linguistic processing (phonetic and semantic) but were similar during nonlinguistic processing (pure tones) and (5) reaction time was found to be longest for semantic processing whereas performance accuracy was found to be an insensitive measure. These results provide insight into brain processes underlying the perception of speech. Furthermore, they support a dual model of speech perception that includes parallel and serial processing.

Adolescent↗