# Factors influencing objective voice profile and speech intelligibility of patients after oral oncological treatment: a prospective cohort study

## TL;DR

This study introduces a new method to objectively assess voice changes in patients after oral cancer treatment and finds factors affecting voice and speech intelligibility.

## Contribution

A novel objective method to assess perceptual voice profile changes after oral oncological treatment is introduced.

## Key findings

- Voice profile and speech intelligibility are significantly impacted up to 12 months after treatment.
- Age, tobacco use, tumor stage, and surgical reconstruction type influence the severity of voice and intelligibility changes.
- Radiotherapy is associated with changes in voice profile but not with reduced speech intelligibility.

## Abstract

While objective assessment of speech intelligibility after oral oncological treatment has proven reliable, no such method currently exists for assessing changes in perceptual voice profile. In this study, we introduce a novel objective method to assess changes in perceptual voice profile after oral oncological treatment. Subsequently, we identify demographic and clinical factors associated with objective assessments of voice profile and intelligibility from the pre-treatment stage up to 12 months after treatment.

Speech samples were collected from 140 patients pre-treatment (baseline) and 1, 6, and 12 months post-treatment. Neural speaker embeddings were used to measure changes in voice profile relative to the pre-treatment stage while an automatic speech recognition system determined speech intelligibility. A linear mixed-effects model was used to associate demographic and clinical factors with both measurements over time.

Voice profile and speech intelligibility of patients were significantly impacted 1, 6, and 12 months after treatment compared to the baseline measurements. Increased age and tobacco usage were associated with worse intelligibility before treatment. Advanced tumor stage, bone flap reconstruction, local flap reconstruction, and their interaction with the timing of assessment were associated with both voice profile and intelligibility. Radiotherapy was associated with changes in voice profile 6 and 12 months after treatment but did not interact significantly with intelligibility.

Voice profile and speech intelligibility are significantly affected after oral oncological treatment. The severity is influenced by age, tobacco usage, tumor stage, and surgical reconstruction type. Radiotherapy seems to change voice profile rather than reducing intelligibility.

The online version contains supplementary material available at 10.1007/s00520-025-09793-z.