Supplementary Material for: Digital vocal biomarker of smoking status using ecological audio recordings: results from the Colive Voice study

Introduction

The complex health, social, and economic consequences of tobacco smoking underscore the importance of incorporating reliable and scalable data collection on smoking status and habits into research across various disciplines. Given that smoking impacts voice production, we aimed to develop a gender and language-specific vocal biomarker of smoking status.

Methods

Leveraging data from the Colive Voice study, we used statistical analysis methods to quantify the effects of smoking on voice characteristics. Various voice feature extraction methods combined with machine learning algorithms were then used to produce a gender and language-specific (English and French) digital vocal biomarker to differentiate smokers from never-smokers.

Results

A total of 1332‬ participants were included after propensity score matching (mean age = 43.6 (13.65), 64.41% are female, 56.68% are English speakers, 50% are smokers and 50% are never-smokers). We observed differences in voice features distribution: for women, the fundamental frequency F0, the formants F1, F2 and F3 frequencies and the harmonics to noise ratio (NHR) were lower in smokers compared to never-smokers (P<0.05) while for men no significant disparities were noted between the two groups. The accuracy and AUC of smoking status prediction reached 0.71 and 0.76 respectively for the female participants, and 0.65 and 0.68 respectively for the male participants.

Conclusion

We have shown that voice features are impacted by smoking. We have developed a novel digital vocal biomarker that can be used in clinical and epidemiological research to assess smoking status in a rapid, scalable and accurate manner using ecological audio recordings.