A Functional Photoplethysmography Device Measuring Changes in the Auditory Cortex During the Application of Emotional Sound

In this work, the efficacy of photoplethysmography system for measuring the hemodynamic activity of the auditory cortex of 5 adults was verified. In which the signal of a photo diode placed in T4 of the 10–20 system caused by the interaction of a beam of infrared light of 850nm was recorded. The light that reaches the photodiode is amplified and sent via serial to a computer where it is displayed and stored. The study subjects listened to a series of sounds that they considered pleasant and a condition without sound. The results indicate that during a period of sodium absence the subjects present a semi-constant basal photoplesmographic signal. And during the time that a pleasant sound is heard, the signal presents a significant increase that attenuates, reaching the basal level, when the sound ends. The increase and attenuation of the photoplestimographic signal that occurs when listening to a pleasant sound has a delay from its minimum level to its maximum level and vice versa. Obtaining a signal with different time constants that depend on the study subjects.