Nagalapura S. Viswanath

Acoustic pattern variations in the female-directed birdsongs of a colony of laboratory-bred zebra finches.

The acoustic profile of the zebra finch song is characterized by a series of identical repeating units, each comprising a distinctive sequence of acoustic elements, called syllables. Here, we perform an analysis of song pattern deviations caused by variabilities in the production of song syllables. Zebra finches produce four different kinds of syllable variabilities-syllable deletions, single or double syllable insertions, syllable alterations, and syllable repetitions. All these variabilities, with the exception of repetitions, are present in songs of more than two-thirds of the normal adult birds; repetitions are present in less than one-fifth of birds. The frequency of occurrence of these variabilities is independent of the amount of singing, suggesting that they are unlikely to result simply from singing-induced physiological changes such as fatigue. Their frequencies in tutor-deprived birds are not significantly different from those in normal birds, indicating that they are unlikely to be acquired due to deficiencies in tutor-dependent learning. The types, patterns of occurrence and relative frequencies of these song syllable variabilities might reveal insights into the functioning of the song motor control pathway.

Evaluation of the speech motor control system in amyotrophic lateral sclerosis

Summary We examined 162 amyotrophic lateral sclerosis patients and a subsequent group of 81 patients, addressing clinical aspects of bulbar dysfunction. All patients with deglutition complaints also had speech symptoms. The jaw jerk reflex and gag reflex had no relation to speech symptoms. Fundamental frequency ( F 0 ) range for /i/ failed to predict longevity. Patients without speech symptoms all spanned at least one octave in F 0 output. Tongue denervation on electromyography testing was not related to speech symptoms. Repetitive output of /pa/, /ta/, and /ka/, when performed at slow and fast rates, sometimes revealed substitution of voiced cognates as well as nasal consonants with the same place of articulation as for the voiceless stops, suggesting velopharyngeal dysfunction.

Disorders with Excessive Muscle Contraction: Candidates for Treatment with Intramuscular Botulinum Toxin (“Botox”)

The initial clinical use of local injections of type A botulinum toxin (botox) was for the treatment of strabismus.1 The intended goal was to block acetylcholinergic neuromuscular junctions and rebalance neural input to the extraocular rectus muscles; this enhanced convergence.2 Several drugs, including alpha-bungarotoxin, had been considered prior to botox, but each had limitations. These included lack of selectivity, undesired side effects, short duration of action, and substantial antigenicity. Botox has the advantage of being apotent neuromuscular blocking agent while not suffering as many limitations as other putative therapeutic agents.

Global- and local- temporal effects of a stuttering event in the context of a clausal utterance

Abstract The two main purposes of the study were (a) to relate the course of the global variables, Total Articulation Time (TAT) and Total Pause Time (TPT), with the frequency of stuttering events during adaptation; and (b) to examine the duration of words in various locations in the vicinity of stuttering events in the context of clausal utterances. Four stutterers provided two corpora of utterances comprising of (1) 40 utterances (8 clauses x 5 readings), with only the first reading of each clause containing a stuttering event, and (2) 40 fluent utterances (2 clauses x 5 readings x 4 stutterers). Utterances of identical clauses were obtained from matched control speakers to form two additional corpora. The main findings based on spectrographic durational measurements were that (a) the reduction of TAT and TPT through the readings paralleled the reduction of stuttering events, (b) the TAT and TPT functions were similar in stutterers corpora, and (c) stutterers reduced TAT and TPT through the readings more than the control speakers. The analysis of the duration of words in the vicinity of stuttering events revealed that (a) there are anticipatory and carryover effects in the immediate vicinity of stuttering events in a clausal utterance; (b) the anticipatory effects were more pronounced than the carryover effects; and (c) a significant durational difference between stutterers and fluent speakers, in the duration of the last word of a clausal utterance preceding a clausal utterance containing a stuttering event, was noted. The results have been discussed in the context of literature on planning and production of speech.

Preponderance of Lead Voice Onset Times in Stutterers Under Varying Constraints

Differences between stutterers and nonstutterers in temporal organization of fluent speech may offer clues to the elemental basis of fully elaborated, perceptible stuttering events. Guided by this hypothesis, we investigated voice onset time—the interval between voice onset and upper articulatory stop release—in voiced stop consonants under varying constraints. Under variation of rate, lexical stress location, and location of key words beginning with voiced stops, the stutterers realized voiced stops by voicing before release (prevoicing), whereas the controls realized voiced stops by voicing following the release. The significance of this phonetic strategy difference for understanding and treating stuttering is discussed.

Overt phonological errors during part-word repetitions : Some theoretical implications

Abstract This is a report of a single-subject study of a stutterer who produced systematic overt phonological errors only during part-word repetitions. The phonological errors involved substitution of initial voiceless cognates for the intended voiced stops during repetitions and final fluent productions of the target words. In contrast, the subject did not produce phonological errors during part-word repetitions of words beginning with the voiceless stops and when he produced words with initial voiced stops fluently. Acoustic measurements confirmed these auditory-perceptual judgments. The implications of these findings for the Covert Repair Hypothesis (CRH) ( Postma and Kolk, 1993 ; Journal of Speech and Hearing Research 16, 472–487) will be discussed.