心率變異度的高低可以反應一個人的自律，神經是否失調，心臟功能的健康，而低變異度代表著高心臟病危險性。然而一般在以 ECG量測心律時，受測者會在有意識到要被量測的心理壓力及量測電極所造成的生理不適狀態下，而無法量測到受測者自然狀況下的心律變異。為了消除這些因素本研究發展出ㄧ個不會使受測者意識到被量測的裝置，耳戴式 PPG量測裝置，來測量心律變異，以取得受測者自然的心律變異。本研究設計四種狀態，分別為無聽音樂 ECG、無聽音樂 PPG、有聽音樂 ECG和有聽音樂 PPG這四種類型，利用 T-TEST分析四種類型的 HRV參數，證明音樂和不同的量測方式對使用者是有影響的，並把每種類型的時頻域頻譜做成圖像以影像處理之方法利用自相關分析，做交叉比對，分析統計量測心電圖與量測 PPG方式之差異，辯證於耳機內裝設 PPG量測系統，在受測者聆聽音樂時不自覺之狀況下使用 PPG量測方式，可較 ECG快達到心律變異的穩定也就是較為放鬆，且取得長期的自然心率變異資訊，以驗證本研究所設計之裝置在
生理功能量測及心跳監測上較優於 ECG裝置的量測。

This innovation is related to measuring the heart rate under unawareness of subject to extract the true nature heart rate variability. The heart rate variability (HRV) is an important index that could be used for long term monitor of cardiac function. The low variability of heart rate indicates that the cardiac rhythm could not be regulated by
autonomic nerve system. This concept of monitoring vital under unawareness of subject has been innovated and devised into a portable apparatus that was monitoring photo-plethysmo-graphy (PPG) through an ear plug appliance. The system was used in assessing the psychophysical effect of heart beat monitoring over four circumstances.
These were the situation of monitoring the ECG without listening to music, assessing the PPG without listening to music, listening to music with monitoring the ECG, and listening to music with the assessment of PPG. Four types of HRV parameters were analyzed among named four circumstances using Student’s T-TEST. These were to examine the impact of heart beat monitoring methods on users. While examining the HRV frequency spectrum against each testing situation, the parasympathetic tone was found activated much earlier using PPG to assessing heart beat than the using ECG.
This result demonstrated that the subjects’ heat rate and their natural heart rate variability could be monitored unconsciously using PPG while listening to music.