We report on the emergence of functional flexibility in vocalizations of human infants. This vastly underappreciated capability becomes apparent when prelinguistic vocalizations express a full range of emotional content-positive, neutral, and negative. The data show that at least three types of infant vocalizations (squeals, vowel-like sounds, and growls) occur with this full range of expression by 3-4 mo of age. In contrast, infant cry and laughter, which are speciesspecific signals apparently homologous to vocal calls in other primates, show functional stability, with cry overwhelmingly expressing negative and laughter positive emotional states. Functional flexibility is a sine qua non in spoken language, because all words or sentences can be produced as expressions of varying emotional states and because learning conventional "meanings" requires the ability to produce sounds that are free of any predetermined function. Functional flexibility is a defining characteristic of language, and empirically it appears before syntax, word learning, and even earlier-developing features presumed to be critical to language (e.g., joint attention, syllable imitation, and canonical babbling). The appearance of functional flexibility early in the first year of human life is a critical step in the development of vocal language and may have been a critical step in the evolution of human language, preceding protosyntax and even primitive single words. Such flexible affect expression of vocalizations has not yet been reported for any nonhuman primate but if found to occur would suggest deep roots for functional flexibility of vocalization in our primate heritage.esearch on evolution and development of language has been devoted primarily to syntax, the uniquely human capacity to produce well-formed complex sentences (1-4). Additional work has targeted the emergence of simpler communicative structures and thus has shifted attention back in evolutionary time to an earlier possible split of hominins from the primate background. For example, research has considered the presumably earlier evolution of simple sentences or "protosyntax" (5). Other work influenced by recent trends in evolutionary developmental biology (evo-devo) (6, 7) has focused on infrastructure for language, invoking capabilities logically more foundational even than protosyntax and presumably moving the communicative differentiation of hominins from other primates much farther back. For example, symbolic expression in single words beginning in modern human development at about 12 mo is a precursor to even the simplest syntax (8). Moving the evolutionary focus even farther back in time, joint attention-infant pointing with gaze alternation between an object and an adult interactor, occurring before the end of the first year-is deemed a critical precursor to words (9). Similarly, canonical babbling (onset at about 7 mo) is a crucial step toward verbal vocabulary because development and imitation of canonical syllables (e.g., "baba") is required for extensive word lear...

This paper will provide a review of aspects of vocal aging within the context of general body aging and describe two data sets related to the aging voice. Data will be presented which document pre- to posttreatment improvement in select voice characteristics (sound pressure level, subglottal air pressure, thyroarytenoid laryngeal muscle activity and voice quality) following application of an intensive voice treatment program (the LSVT^®) to 3 individuals with aged voice. Additionally, physiological data (forced expiratory volume, visual accommodation, bone density, taste discrimination, white blood count and resting heart rate) and select perceptual (perceived age) and acoustic measures (reflecting both cycle-to-cycle and longer-term intensity and frequency stability) from 67 subjects will be reviewed from the work of Gray and colleagues to document the differential impact of the global aging process across organ systems including the aging voice.

Phrasing is a universal characteristic of human communication, and the present investigation explored its developmental roots in nonvegetative, prelinguistic vocalizations. Adult judges identified a hierarchical arrangement of syllables embedded within utterances and utterances embedded within prelinguistic phrases in the vocalizations of infants. Prelinguistic phrases were characterized by systematic lengthening of phrase final syllables, temporal patterning, and stable durations across development that were similar to those of some cross-culturally optimal rhythmic units from other domains. Analyses of vocalizations of infants with Down syndrome indicated similar internal structure of prelinguistic phrases to those of typically developing infants, but with longer durations. These findings suggest that relative durational characteristics of prelinguistic phrasing are stable features of early vocal behavior, although the absolute durational characteristics of prelinguistic phrases can be impacted by a complex and severe disorder such as Down syndrome.

How did vocal language originate? Before trying to determine how referential vocabulary or syntax may have arisen, it is critical to explain how ancient hominins began to produce vocalization flexibly, without binding to emotions or functions. A crucial factor in the vocal communicative split of hominins from the ape background may thus have been copious, functionally flexible vocalization, starting in infancy and continuing throughout life, long before there were more advanced linguistic features such as referential vocabulary. 2–3 month-old modern human infants produce “protophones”, including at least three types of functionally flexible non-cry precursors to speech rarely reported in other ape infants. But how early in life do protophones actually appear? We report that the most common protophone types emerge abundantly as early as vocalization can be observed in infancy, in preterm infants still in neonatal intensive care. Contrary to the expectation that cries are the predominant vocalizations of infancy, our all-day recordings showed that protophones occurred far more frequently than cries in both preterm and full-term infants. Protophones were not limited to interactive circumstances, but also occurred at high rates when infants were alone, indicating an endogenous inclination to vocalize exploratorily, perhaps the most fundamental capacity underlying vocal language.

Background: Voice tremor, like spasmodic dysphonia and other tremor disorders, may respond to botulinum toxin type A injections.Objective: To evaluate the safety and efficacy of botulinum toxin type A injections as treatment for voice tremor.Design: A randomized study of 3 doses of botulinum toxin type A with 6 weeks of follow-up.Setting: A single-site tertiary care center.Participants and Methods: Thirteen subjects (11 women, 2 men; mean age, 73 years) with voice tremor and no spasmodic dysphonia or head, mouth, jaw, or facial tremor were entered into this study. Patients received 1.25 U (n = 5), 2.5 U (n = 5), or 3.75 U (n=3) of botulinum toxin type A in each vocal cord. All patients were evaluated at baseline and postinjection at weeks 2, 4, and 6. Main Outcome Measures:The primary outcome measure was the patient tremor rating scale, with secondary measures including patient-rated functional disability, response rating scale, independent randomized tremor ratings, and acoustical measures.Results: All patients at all dose levels noted an effect from the injection. The mean time to onset of effect was 2.3 days (range, 1-7 days). For all patients combined, mean tremor severity scale scores (rated by patients on a 5-point scale) improved 1.4 points at week 2, 1.6 points at week 4, and 1.7 points at week 6. Measures of functional disability, measures of the effect of injection, independent ratings of videotaped speech, and acoustic measures of tremor also showed improvement. The main adverse effects at all doses were breathiness and dysphagia. Conclusion:Voice tremor improves following injections of botulinum toxin type A.