P‐208: Late‐News‐Poster: Interdisciplinary Research on Acoustic and Human Cognitive Characteristics of Flat‐Panel TVs: Front‐Firing Exciter Speaker Characteristic
Authors: Lee Sungtae , Park Kwanho , Park Sinkyun 
Published: September 2020

Technological advances in the display industry have allowed organic light‐emitting diode panel manufacturers to create ultra‐wider‐screen, high‐picture‐quality, high‐sound‐quality TVs. In the previous research, we have been studied the characteristics of the sound on the screen directly by excite speaker, with the panel of OLED. Unlike LCD, the OLED emits light and composes pictures without complex sheets such as BLU so that the panel can play the role of a diaphragm of a general dynamic speaker.

Sound is free to propagate by the vibration of the air. And this air vibration can be information or noise. In this case, when the information is used, the sound is the information required by the listener, and when the opposite listener is not needed or not desired, the noise may be referred to. In addition, the sound is perceived through human auditory organs. At this time, excessively loud volume causes noise‐induced hearing loss. Furthermore, rather degrades information transmission. Depending on the wave motion characteristics of the sound, the phenomenon of refraction, reflection, diffraction occurs, and forms a sound field. As shown in Fig. 1 and Fig. 2, the sound field is distributed differently according to the ordinary dynamic speaker system and exciter speaker system. It is the same thing that occurs in a speaker, but as it propagates, it is different from being concentrated or evenly spread in one place by the effects of refraction and reflection. When the sound is aggregated, the sound quality may be improved by interference between frequencies, but the resolution is often lowered. That is, the down‐firing sound by the existing dynamic speaker has low sound intelligibility. On the other hand, the proposed exciter speaker spreads evenly around the sound sourced directly from the center of the screen and has less influence of the reflected sound source, thus including the information of the original sound well.

As shown in Figures 1 and 2, the sound quality of TV sets is also different. Cognitive analysis was performed through listening analysis. Over 150 people watched the same video and conducted a survey. The experiment was to watch TV sitting on the front and side, a group of about ten people at a time. The videos used in the experiments utilized news, classical music, and pop music, and alternately listened and tested for about 30 seconds. After watching the audience, they responded to the cognitive differences in sound quality. The questionnaire asks three kinds of questions. The analysis was performed by factor analysis, reliability analysis, and T‐test. The exploratory factor analysis and reliability analysis results have been fully validated. Cronbach's alpha is above 0.8, and the results are highly reliable. In the T‐test analysis, the t value was significantly obtained as ‐8.684. The sound quality of the two TV sets is different, which means that the average of the indirect sound TV(down‐firing) set is 3.860, and that of the direct sound TV(exciter speaker) set is 4.528, which means the clarity of the direct sound TV set is high.

Audiovisual is an essential component of information delivery. The technology of panel makers is improved, and image quality can go beyond HD to achieve ultra‐high resolution of 8K. Sound is also developing through exciter speakers. In this study, Interdisciplinary research was conducted on the information transmission and sound quality of moving images through acoustic and cognitive analysis of down‐ and front‐firing sound sources. In acoustic analysis, the conventional dynamic method is reflected, and the formation of sound fields is disadvantageous. Cognitive analysis showed that the direct sound was easy to understand and accurate. In the future, we will conduct additional studies to improve the objective and subjective sound quality by conducting acoustic and cognitive analysis studies according to various spatial conditions.