Objective
This study evaluated the correspondence between in-lab and real-world assessments of vocal efficiency (VE) to examine how laboratory measures relate to habitual voice use in individuals with and without voice disorders.

Methods
Fourteen female participants (seven with muscle tension dysphonia and seven age-, sex-, and occupation-matched vocally healthy controls) were recruited at Massachusetts General Hospital. In-lab VE, defined as the ratio of sound pressure level (SPL) to subglottal pressure (Ps), was obtained using /p/-vowel sequences across varied loudness and pitch, with SPL measured via microphone and Ps estimated from intraoral pressure. Participants then completed approximately three days of ambulatory voice monitoring during daily activities using a smartphone-based wireless neckband. The ambulatory system integrates a microphone and neck-surface accelerometer, enabling continuous estimation of SPL/Ps ratio in natural environments. The average (median) and variability (standard deviation; SD) of VE were computed separately for in-lab tasks and daily ecological VE.

Results
Participants yielded 45 total monitoring days (average 13.2 hours/day; range: 11–18 hours/day), enabling comparisons between in-field VE patterns and in-lab findings. Both patient and control groups exhibited statistically similar average VE computed from the in-lab and ambulatory settings. However, a statistically significant decrease in VE variability during daily activities was observed in the patient group with a large effect size, with VE SD decreasing from 0.97 dB/dB in lab to 0.43 dB/dB in field (p = 0.016, r = 0.91); in contrast, VE SD in the control group was similar in the in-lab and in-field settings (0.50 and 0.51dB/dB).

Conclusion
These pilot data showed that in-lab assessments of individuals with muscle tension dysphonia may overestimate VE variability when compared to ambulatory measurements. Future investigation is required in larger, diverse diagnostic cohorts to document the impact of voice disorders on measures of vocal efficiency as individuals go about their daily lives.