Riki Taitelbaum-Swead

Prelexical vocalization in normal hearing and hearing-impaired infants before and after cochlear implantation and its relation to early auditory skills.

Objectives: To compare the vocalizations of hearing-impaired infants before and after cochlear implantation with those of a control group of hearing infants and to relate prelexical vocalizations by using the PRoduction Infant Scale Evaluation (PRISE) to early auditory skill attainments, using the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) in normal-hearing and hearing-impaired (HI) infants before and after cochlear implantation. Design: A total of 187 infants participated in the study: 24 HI infants with severe-profound hearing loss (8 to 23 months of age) and 163 hearing infants (0.5 to 20 months of age). Prelexical vocalizations and early auditory skills were assessed by using parent questionnaires (PRISE and IT-MAIS, respectively) that reflect known milestones in the infant’s vocal and auditory development. HI infant data were compared with hearing infant data according to chronological age and duration of device use (hearing aid or cochlear implant). Results: Average PRISE score of aided HI infants before implantation was 50% or less (regardless of age). This score is comparable to that of hearing infants who are 6 to 7 months of age. After implantation, HI infants reached a score of 70% but did not reach normative performance. When HI infant data were compared with hearing infants by duration of device use, aided infants before implantation performed as well or worse than normative performance, whereas implanted infants performed as well as or better than hearing infants. Performance on individual PRISE questions showed limited ability by HI infants before implantation compared with hearing and implanted infants. A strong correlation was found between the IT-MAIS and the PRISE (r = 0.93 and r = 0.83, for hearing and HI infants, respectively). Conclusions: The PRISE was found to be a versatile tool for implant team clinicians who are required to assess prelinguistic skills of infants. The findings suggest that early auditory skills are related to prelexical vocalization. The data also highlighted unanswered questions related to the importance of early fitting of hearing aids on vocalization before and after implantation.

The R245X Mutation of PCDH15 in Ashkenazi Jewish Children Diagnosed with Nonsyndromic Hearing Loss Foreshadows Retinitis Pigmentosa

Usher syndrome is a frequent cause of the combination of deafness and blindness due to retinitis pigmentosa (RP). Five genes are known to underlie different forms of Usher syndrome type I (USH1). In the Ashkenazi Jewish population, the R245X mutation of the PCDH15 gene may be the most common cause of USH1 (Ben-Yosef T, Ness SL, Madeo AC, Bar-Lev A, Wolfman JH, Ahmed ZM, Desnick RK, Willner JP, Avraham KB, Ostrer H, Oddoux C, Griffith AJ, Friedman TB N Engl J Med 348: 1664–1670, 2003). To estimate what percentage of Ashkenazi Jewish children born with profound hearing loss will develop RP due to R245X, we examined the prevalence of the R245X PCDH15 mutation and its carrier rate among Ashkenazi Jews in Israel. Among probands diagnosed with nonsyndromic hearing loss not due to mutations of connexin 26 (GJB2) and/or connexin 30 (GJB6), and below the age of 10, 2 of 20 (10%) were homozygous for the R245X mutation. Among older nonsyndromic deaf individuals, no homozygotes were detected, although one individual was heterozygous for R245X. The carrier rate of the R245X mutation among the normal hearing Ashkenazi population in Israel was estimated at 1%. Ashkenazi Jewish children with profound prelingual hearing loss should be evaluated for the R245X PCDH15 mutation and undergo ophthalmologic evaluation to determine whether they will develop RP. Rehabilitation can then begin before loss of vision. Early use of cochlear implants in such cases may rescue these individuals from a dual neurosensory deficit.

Factors affecting choice of device by cochlear implant candidates.

Objective: To investigate the ways the various cochlear devices are chosen by candidates/surrogates and analyze the factors that influenced their decisions. Setting: University-affiliated tertiary referral center. Method: A questionnaire that included general items and questions on devices aesthetics, technical considerations, and quality was sent to 429 patients who underwent cochlear implantation between June 1997 and December 2006 in our department. Results: One hundred eighty-four questionnaires were returned, yielding a response rate of 42.9%. Some patients did not receive the questionnaires because of the postal address changes. In addition, recently implanted patients/their surrogates were more ready to answer on the questionnaire on decision-making process compared with those who received their devices before 2001. The Nucleus users were more influenced by the questions pertaining to the quality/reliability of the device than the aesthetic and technical aspects. The ABC users were more influenced by the aesthetic aspects, and the MED-EL users were generally influenced by all the groups of questions equally. Females used the Internet as the source of information on the devices significantly more than males, and their decisions were more influenced by their families than those of the males. In addition, the females were more influenced by the quality of a devices function compared with males. Pediatric candidates (aged 1-16 yr) were significantly more influenced by the experience of other implant users, the medical staff, and religious considerations than adults. Adults arrived at decisions more easily than children or their surrogates. The adults and older children were more influenced by the ease of the devices functioning compared with the young children. Conclusion: Choosing the type of cochlear implant device is a highly individualized process that depends on various personal, social and cultural factors, and factors linked directly to the device itself.

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.

Are changes in pitch and formants enough to influence talker normalization processes in children and adults

In the present study, we examined the influence of mean F0 and formant values on talker normalization. Initially, two speakers recorded an identical set of 10 isophonemic word lists in Hebrew, consisting of 10 words each. These recordings were then manipulated by means that affect F0 only, or both F0 and formant frequencies. Different degrees of manipulation were carried out in order to create a new set of lists which were perceived to have been obtained from multiple talkers. The original and manipulated lists were presented to a group of 12 adults and 12 children at 30 dB above pure-tone average thresholds (PTA). Half of the listeners was presented with the single-talker lists first and then the multiple-talker lists, and the other half was presented with the word lists in reversed order. Listeners were instructed to repeat the words they heard. Correct word recognition was scored. The results indicated: (1) lower word recognition scores for the multiple-talker lists than for the single-talker lists, for both children and adults, (2) larger inter-subject variability in performance for the multiple-talker compared to the single-talker lists for both age groups, and (3) that order of presentation influenced word recognition of the multiple-talker lists only, being worse when presented first. Our findings support the following: (1) manipulations of F0 and formants of a single talker are sufficient to influence talker normalization processes, (2) this influence varies between listeners suggesting that listeners do not use the same acoustic information in their speech perception process, and (3) even adults, who are proficient in the language, do not eliminate entirely the irrelevant talker-specific acoustic information in the speech perception process.