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.