Effects of Voicing and Syntactic Complexity on Sign Expression in Adductor Spasmodic Dysphonia

Abstract

Clients with adductor spasmodic dysphonia (ADSD) tend to exhibit inter- and intraclient variability of signs and symptoms. This variability may result in inaccurate assessment of severity. Accurate assessment of severity requires knowledge concerning the factors that affect the expression of ADSD signs and symptoms. This study examined ADSD sign expression as a function of voicing and syntactic complexity. Fifteen ADSD participants and 15 control participants completed a task consisting of 30 sentences. ADSD signs were significantly more frequent in predominantly voiced sentences than in predominantly voiceless sentences, regardless of level of syntactic complexity. Center-embedded sentences comprising predominantly voiced consonants were found to evoke the greatest number of ADSD signs. These results have important implications for the assessment of ADSD.

Toward Improved Differential Diagnosis of Adductor Spasmodic Dysphonia and Muscle Tension Dysphonia

“…Our results replicate Erickson's [7] report of greater sign expression in ADSD during voiced consonants as compared to voiceless consonants and confirm task specificity as a feature of ADSD that potentially distinguishes it from MTD. Erickson [7] attempted to explain increased sign expression during voiced phonemes in ADSD as reflecting an underlying movement control disorder that affects vocal fold adduction for phonation onset.…”

“…Our results replicate Erickson's [7] report of greater sign expression in ADSD during voiced consonants as compared to voiceless consonants and confirm task specificity as a feature of ADSD that potentially distinguishes it from MTD. Erickson [7] attempted to explain increased sign expression during voiced phonemes in ADSD as reflecting an underlying movement control disorder that affects vocal fold adduction for phonation onset. Erickson [7] reasoned that speech tasks that require rapid laryngeal adjustment should be most impaired, and suggested that more ADSD signs should occur following voiced plosives, because the The percentage of subjects meeting the cutoff criterion for each disorder group was calculated by subtracting an individual participant's mean severity rating for the voiceless sentence from their mean severity rating for the voiced sentence.…”

“…In patients with ABSD who produced sentences loaded with voiceless consonants versus sentences loaded with voiced consonants, Dedo and Shipp [6] observed more abductor spasms after production of voiceless consonants, and improved performance (i.e., fewer abductor spasms) for the 'all-voiced' sentence. More recently, additional empirical evidence of differential performance based on phonetic (voicing) context has been reported for ADSD [7] . Erickson [7] reported that sentences loaded with voiced consonants provoked more frequent and severe spasms/voice breaks.…”

“…More recently, additional empirical evidence of differential performance based on phonetic (voicing) context has been reported for ADSD [7] . Erickson [7] reported that sentences loaded with voiced consonants provoked more frequent and severe spasms/voice breaks. In contrast, sentences loaded with voiceless consonants provoked fewer adductor spasms.…”

“…No difference in performance based upon phonetic content was observed for normal speakers (i.e., non-voice-disordered). This differential performance based upon task and phonetic context provided evidence for task specificity in ADSD, but Erickson [7] strongly cautioned that task specificity in voice disorders like MTD had not been explored extensively. In this regard, the seemingly constant hyperfunction of the intrinsic and extrinsic laryngeal musculature has led some observers to assert that the dysphonia in MTD is not believed to vary according to task or phonetic context, and thus is not considered task-specific.…”