Características da espectrografia de banda larga e estreita da emissão vocal de homens com laringe sem afecções

Glottal Voice Distortions: Nasolaryngoscopic and Spectral Analysis of Anatomophysiologic Changes in Singing Voice

The distorted voices, commonly called vocal drives in Brazil and in some other South American countries, are vocal ornaments belonging to the aesthetics of popular singing and desired by singers of different styles. The advances in vocal sciences have allowed the demystification of this type of technique in the last four decades, classifying them as glottal, supraglottic or mixed distortions/drives. The interdisciplinary approach in the evaluation of singers who use glottal distortions is fundamental for a broad understanding of the particularities of each case. The present study has as main objective to describe the anatomophysiological and spectral findings of the glottal distortions, identified in the practice of many singers. A sample of three singers in a sung emission with and without vocal distortions was collected. PreSonus® AudioBox Studio One kit was used to record the voice during the nasolaryngoscopic evaluation. The singers underwent vocal warm-up and functional evaluation of the larynx based on two studies on contemporary singers. The singers performed the Snarl Voice and Phaser distortions and both showed particular anatomophysiological behaviors. The larynx was low in the first distortion and the level of the clean voice in the second, with the posterior opening of the glottis in both distortions being observed, with opening of the middle third of the glottis for the first as well. Formants vary according to the vocal tract settings used for the distortions. The glottic distortions present a complex anatomophysiological behavior in their composition, with fundamental participation of the transverse interarytenoid muscle and lateral cricoarytenoids, as well as the the participation of the vocal fold in the frequency break. F3 varied according to the longitudinal length and F4 with the diameter, both being related to the three-dimensional adjustments of the vocal tract.

Evidence of Internal Consistency in the Spectrographic Analysis Protocol

OBJECTIVE

To verify the validity in the internal consistency in the spectrographic analysis protocol (SAP).

MATERIAL AND METHODS

Thirty-nine students of the Speech-Language Pathology graduate program and 38 speech-language pathologists, specialized in voice, participated in the study. The participants made visual inspections of 10 spectrograms and marked the items of the SAP. For analysis of the internal consistency in the SAP, the exploratory factor analysis (EFA) and confirmatory factor analysis were performed.

RESULTS

Most items showed corrected item-total correlation above 0.3, indicating that the items have a good relationship with each other and with the SAP as a whole. Six items presented values below the average, suggesting the exclusion of these from the construct. However, three of these were maintained because they were judged as important parameters in clinical practice, requiring the training of judges when using the SAP to properly understand the items. The EFA regrouped the previous domains of the SAP into three factors. All items presented a factor load above 0.4, suggesting the retention of all, except for the items previously indicated, for exclusion. The confirmatory factor analysis corroborated with the EFA and its indexes.

CONCLUSION

The SAP has good internal consistency. All items have a good degree of relationship with each other and contribute positively to the protocol as a whole. The final version of the SAP, at this stage, has 15 items (from the 25 items of the initial SAP version), distributed among three domains.

Spectrographic Vocal Assessment Protocol (SVAP): Reliability and Criterion Validity

OBJECTIVE

To present evidence of the reliability and validity in the Spectrographic Vocal Assessment Protocol.

METHODS

The sample consisted of 50 female participants, aged 25-62 years old, 24 with a otorhinolaryngological diagnosis of the normal larynx or posterior glottal gap, and 26 diagnosed with vocal fold disturbances. The emission of the vowel /a:/ was analyzed by the Real Time Spectrogram software. The spectrographs were analyzed with a protocol by two speech therapist judges. For reliability analysis, inter- and intrajudge analysis were performed using the Kendall coefficient. For criterion validity, the t test for matched samples with Bonferroni correction was used to compare the average performance of the protocol between the two groups of subjects.

RESULTS

Protocol reliability: for broadband items, the agreement between judges ranged from moderate (0.462) to almost perfect (0.888), and it is significant for all items, and an intrajudge agreement was almost perfect and significant (0.865-1.000) for all items. For narrowband items, the agreement between judges ranged from moderate (0.469) to almost perfect (0.922), and it is significant for all items except for the presence of "subharmonics in high frequencies" where agreement was moderate (0.504), but not significant, and the intrajudge agreement was almost perfect (0.874-1.000) and significant for all items. Criterion validity: for most broadband and narrowband items, the groups with normal or altered diagnosis differed statistically.

CONCLUSION

The Spectrographic Vocal Assessment Protocol presented adequate evidence in reliability and validity.

Development and Evidence of Content Validity of the Spectrographic Vocal Assessment Protocol (SVAP)

OBJECTIVE

To develop and seek evidence of content validity of a spectrographic vocal assessment protocol.

METHODS

Methodological study for development and validation of an assessment instrument. A broad literature search was conducted to develop and substantiate a spectrographic vocal assessment protocol. The protocol items were sent to five expert judges, speech therapists, nonauthors of the research, doctors, and clinicians, with experience in the field of voice and spectrographic acoustic analysis, who individually analyzed the protocol items. For data analysis, the Gwet analysis and the Content Validity Ratio formula were used.

RESULTS

The Spectrographic Vocal Assessment Protocol was developed, subdivided into Broadband and Narrowband. Twenty-four protocol items had Content Validity Ratio 1.0 and 25 items had 0.6. Gwet analysis indicated substantial agreement (0.656) for broadband and almost perfect (0.848) for narrowband items.

CONCLUSION

Evidence of satisfactory content validity was obtained in the development of the protocol.