Blood Glucose Estimation From Voice: First Review of Successes and Challenges

Predicting glycemic control status and high blood glucose levels through voice characteristic analysis in patients with cystic fibrosis-related diabetes (CFRD)

Cystic fibrosis-related diabetes (CFRD) is associated with reduced life expectancy in adults with cystic fibrosis (CF). Voice analysis may be a convenient method for diagnosing and monitoring CFRD. This study aims to determine the relationship between voice characteristics and markers of glucose and glycemic control and to identify if voice analysis can predict high blood glucose levels and glycemic control in adults with CFRD. We conducted a prospective cross-sectional study in adults with CF from March to December 2021. We recorded 3-second voice samples of a sustained /a/ vowel and analyzed voice characteristic using the Computerized Speech Lab with the Multi-Dimensional Voice Program. In female participants with CFRD, the noise-to-harmonic ratio was significantly lower in those with HbA1c ≥ 7. Furthermore, fundamental frequency variation was significantly lower in both male and female participants with CFRD who had a glucose level of 200 mg/dL or higher at the time of collection. This finding was also associated with a high level of point-of-care glucose. The human voice has potential as a non-invasive tool for measuring glucose levels and glycemic control status in CFRD patients in the future.

Assessment of the obesity based on voice perception

Human voice is an extremely important biological signal which contains information about sex, age, emotional state, health and physical features of a speaker. Estimating a physical appearance from a vocal cue can be an important asset for sciences including forensics and dietetics. Although there have been several studies focused on the relationships between vocal parameters and ratings of height, weight, age and musculature of a speaker, to our knowledge, there has not been a study examining the assessment of one’s BMI based on voice alone. The purpose of the current study was to determine the ability of female “Judges” to evaluate speakers’ (men and women) obesity and body fat distribution from their vocal cues. It has also been checked which voice parameters are key vocal cues in this assessment. The study material consisted of 12 adult speakers’ (6 women) voice recordings assessed by 87 “Judges” based on a 5-point graphic scale presenting body fat level and distribution (separately for men and women). For each speaker body height, weight, BMI, Visceral Fat Level (VFL, InBody 270) and acoustic parameters were measured. In addition, the accuracy of BMI category was verified. This study also aimed to determine which vocal parameters were cues for the assessment for men and women. To achieve it, two independent experiments were conducted: I: “Judges” had to choose one (obese) speaker from 3 voices (in 4 series); II: they were asked to rate body fat level of the same 12 speakers based on 5-point graphic scale. Obese speakers (i.e., BMI above 30) were selected correctly with the accuracy greater than predicted by chance (experiment I). By using a graphic scale, our study found that speakers exhibiting higher BMI were rated as fatter (experiment II). For male speakers the most important vocal predictors of the BMI were harmonics-to-noise ratio (HNR) and formant dispersion (Df); for women: formant spacing (Pf) and intensity (loudness). Human voice contains information about one’s increased BMI level which are hidden in some vocal cues.

Predicting frailty in older adults using vocal biomarkers: a cross-sectional study

Background

Frailty is a common issue in the aging population. Given that frailty syndrome is little discussed in the literature on the aging voice, the current study aims to examine the relationship between frailty and vocal biomarkers in older people.

Methods

Participants aged ≥ 60 years visiting geriatric outpatient clinics were recruited. They underwent frailty assessment (Cardiovascular Health Study [CHS] index; Study of Osteoporotic Fractures [SOF] index; and Fatigue, Resistance, Ambulation, Illness, and Loss of weight [FRAIL] index) and were asked to pronounce a sustained vowel /a/ for approximately 1 s. Four voice parameters were assessed: average number of zero crossings (A1), variations in local peaks and valleys (A2), variations in first and second formant frequencies (A3), and spectral energy ratio (A4).

Results

Among 277 older adults, increased A1 was associated with a lower likelihood of frailty as defined by SOF (odds ratio [OR] 0.84, 95% confidence interval [CI] 0.74–0.96). Participants with larger A2 values were more likely to be frail, as defined by FRAIL and CHS (FRAIL: OR 1.41, 95% CI 1.12–1.79; CHS: OR 1.38, 95% CI 1.10–1.75). Sex differences were observed across the three frailty indices. In male participants, an increase in A3 by 10 points increased the odds of frailty by almost 7% (SOF: OR 1.07, 95% CI 1.02–1.12), 6% (FRAIL: OR 1.06, 95% CI 1.02–1.11), or 6% (CHS: OR 1.06, 95% CI 1.01–1.11). In female participants, an increase in A4 by 0.1 conferred a significant 2.8-fold (SOF: OR 2.81, 95% CI 1.71–4.62), 2.3-fold (FRAIL: OR 2.31, 95% CI 1.45–3.68), or 2.8-fold (CHS: OR 2.82, 95% CI 1.76–4.51, CHS) increased odds of frailty.

Conclusions

Vocal biomarkers, especially spectral-domain voice parameters, might have potential for estimating frailty, as a non-invasive, instantaneous, objective, and cost-effective estimation tool, and demonstrating sex differences for individualised treatment of frailty.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03237-7.

Scoping review of the relationship between diabetes and voice quality

AIMS

The objective of this scoping review is to synthesize all of the known information about the relationship between diabetes mellitus and voice quality and to explore its potential applications for new technology.

METHODS

We conducted a scoping literature review of articles published between March 2000 and September 2021 using the following databases: PubMed, Web of Science, Scopus, and Embase. Additionally, we did a manual search of Google Scholar. The search strategy abides by the PRISMA-ScR guidelines. Studies pertaining to the relationship between diabetes and the voice were categorized separately for further evaluation.

RESULTS

Out of the 2732 originally identified articles, nine were ultimately included in this scoping review. The chosen articles address both diabetes and its impact on a variety of vocal parameters.

CONCLUSIONS

There is currently very little research investigating the relationship between diabetes, neuropathy, and phonatory symptoms. Additionally, existing publications contain some contradictory findings. Further research that incorporates imaging technology is needed to clarify the physiological explanations for the differences observed between healthy individuals and those with diabetes mellitus. Such information can be used to develop noninvasive technology for diabetes diagnosis and monitoring.