Background: The Test of Masticating and Swallowing Solids (TOMASS) is a validated screening tool for assessing masticatory and swallowing functions. However, the conventional TOMASS relies on operator-dependent methods, which limit its objectivity and efficiency. The neck-worn electronic stethoscope (NWES), a contact sensor positioned on the back of the neck, has recently been developed to automatically detect and monitor swallowing actions through deep learning-based analysis of collected sound data. Objective: This study piloted a semi-automated assessment approach using a NWES to objectively measure TOMASS parameters and examine the influence of age and gender. Methods: A total of 123 healthy adults (mean age: 58.7 ± 18.5 years) consumed two crackers while audio data recorded using a NWES and visual data were collected by smartphone. Measurements included discrete bite count, swallow count, oral processing and swallowing time (OPST), and first OPST (1st-OPST). Statistical analyses were conducted to assess gender- and age-related changes and differences. Results: The NWES enabled objective and precise TOMASS measurements. Age-related prolongation of OPST and 1st-OPST was observed, particularly in men (p < 0.001). Women exhibited fewer age-related changes in OPST, although swallow count tended to decrease with age (p < 0.001). Regarding gender differences, younger women demonstrated higher bite (2.3 [interquartile range (IQR): 1.0–3.0] vs. 1 [IQR: 1.0–2.0], p = 0.042) and swallow counts (2.5 [IQR: 2.0–2.5] vs. 2 [IQR: 1.0–2.0], p = 0.026) compared with men. Conclusion: The NWES appeared suitable as an objective, efficient tool for automated TOMASS evaluation. Age-related changes in masticatory and swallowing performance differed according to gender, highlighting the need for tailored assessments. Future research on NWES-based TOMASS measurements should include diverse populations and extension to dysphagia and masticatory dysfunction.