Purpose: This study examined the relationship between the magnitude of neck-surface vibration (NSV[subscript Mag]; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P'[subscript sg]) during variations in vocal effort at 3 intensity levels. Method: Twelve vocally healthy adults produced strings of /p?/ syllables in 3 vocal intensity conditions, while increasing vocal effort during each condition. Measures were made of P'[subscript sg] (estimated during stop-consonant closure), NSV[subscript Mag] (measured during the following vowel), sound pressure level, and respiratory kinematics. Mixed linear regression was used to analyze the relationship between NSV[subscript Mag] and P'[subscript sg] with respect to total lung volume excursion, levels of lung volume initiation and termination, airflow, laryngeal resistance, and vocal efficiency across intensity conditions. Results: NSV[subscript Mag] was significantly related to P'[subscript sg] (p < 0.001), and there was a significant, although small, interaction between NSV[subscript Mag] and intensity condition. Total lung excursion was the only additional variable contributing to predicting the NSV[subscript Mag]-P'[subscript sg] relationship. Conclusions: NSV[subscript Mag] closely reflects P'[subscript sg] during variations of vocal effort; however, the relationship changes across different intensities in some individuals. Future research should explore additional NSV-based measures (e.g., glottal airflow features) to improve estimation accuracy during voice production.