Sham-Controlled Comparative Study of Image-Derived Thermal Dynamics During Nominal 8 Hz Acoustic Stimulation: Evidence from Hot and Cold Liquids

This study presents a sham-controlled comparative investigation of image-derived thermal dynamics during nominal 8 Hz acoustic stimulation using infrared thermography. The primary objective was to determine whether the thermal patterns previously observed during acoustic stimulation differ from the natural thermal evolution of liquids under identical experimental conditions. Four experimental conditions were evaluated: hot coffee with 8 Hz acoustic stimulation, hot coffee sham (no stimulation), cold water with 8 Hz acoustic stimulation, and cold water sham. All experiments followed an identical protocol consisting of a 1-minute baseline, 2-minute exposure, and 2-minute recovery period. Thermal image sequences were analyzed using Thermal Dynamics Pro v1.0, extracting more than twenty quantitative parameters including thermal statistics, FFT spectral analysis, power spectral density, optical flow, structural similarity (SSIM), fractal dimension, texture metrics, thermal stability indices, and principal component analysis. The sham experiments demonstrated gradual thermal evolution consistent with natural cooling or warming processes. In contrast, nominal 8 Hz acoustic stimulation was associated with distinct image-derived thermal patterns. In hot coffee, stimulation produced sustained elevation of mean thermal intensity during recovery, greater thermal stability, increased surface motion, and the emergence of an approximately 0.066 Hz dominant frequency in two of three experiments. In cold water, stimulation resulted in enhanced surface motion, progressive improvement in thermal stability, structural reorganization reflected by SSIM recovery above baseline, reduction in fractal dimension, and no emergence of the 0.066 Hz spectral component. The comparison indicates that the observed image-derived thermal responses differ from spontaneous thermal evolution and vary according to the initial thermal state of the liquid. While these findings are based on a limited number of experiments and should be considered preliminary, the study provides a reproducible sham-controlled framework for future investigations of low-frequency acoustic stimulation using infrared thermography and quantitative image analysis.