Effects of speaker’s voice pitch variation on listener’s intellectual concentration during online lecture
Authors: Liu Dongliang , Ueda Kimi , Ishii Hirotake , Shimoda Hiroshi , Obayashi Fumiaki 
Published: June 2022

Background & PurposeUnder the Covid-19 pandemic, most schools all over the world had to suspend their face-to-face lectures and adopted online courses instead. Some surveys have revealed that while this new educational format has advantages of convenience and flexibility, there also exist some problems, such as students' increased fatigue and lower intellectual concentration. However, it's difficult to find any effective solutions that can directly improve the intellectual concentration from the students' side currently.To solve this problem, we have focused on the online course system. From the viewpoint of cognitive psychology, sound is one of the essential factors that can influence people's intellectual concentration, and the speakers' voice is one of the most important parts of the sound source in online courses.The purpose of this study is, therefore, to explore the influence of speakers' vocal parameters, specifically pitch variation, on listeners' intellectual concentration during online lectures.Outline of this study(Step1) Selection of the optimal vocal pitch level This step is aiming to select the optimal vocal pitch level that does no harm in keeping intellectual concentration nor increasing the cognitive fatigue among the listeners during the online course system. (Step 2) Exploration of the optimal pitch variation on listeners' intellectual concentrationIn this step, the optimal pitch variation of different patterns on listeners' intellectual concentration will be explored by experiments. For example, Normal Pitch→High Pitch→Normal Pitch (NHN pattern), or Normal Pitch→Low Pitch→Normal Pitch (NLN pattern) etc.(Step 3) Development of feedback control to recover listeners’ intellectual concentrationAfter finding optimal pitch variation for refreshing listeners’ intellectual concentration in step 2, then in this step, feedback-control will be developed to recover listeners’ intellectual concentration during the online course system.In this presentation, we will report the method and result of Step 1.MethodAn experiment was conducted with 6 students at Kyoto University (3 males and 3 females), and all of them are native Chinese speakers.The stimulus given to the participants were lecture videos in which audios in 3 pitch levels (Low, High and Normal) and 2 types of timbre (Male and Female) were prepared.Since this study is focusing on the auditory factors, to simulate the online course system, the audio stimuli using the content of passages of the Reading part in the TOEFL iBT exam were used because they are similar to university-level online course content. Furthermore, to alleviate the influence of different English levels between each participant, all the contents have been translated into Chinese.After listening to each audio, each participant was asked to answer a problem related to the content, and the correct answer rate would be used as a scale of their intellectual concentration level.In addition, their brain waves were measured by a single-channel device, NeuroSky MindWave Mobile 2 headset while they were listening to the audio. The index ‘Attention’ calculated by NeuroSky software has been also used as a reference of listeners’ intellectual concentration level.As a result of the experiment, female voice under normal pitch has been verified as the optimal pitch level to proceed to the next step of this study.