**4. Conclusions**

*The Human Auditory System - Basic Features and Updates on Audiological Diagnosis and Therapy*

**Figure 7** shows changes in β-waves. Consistent results were obtained with regard

The findings related to SVR to evoked potentials of nine participants are shown in **Figure 8**. With regard to the left hemisphere, SVR relative amplitude were consistently and inversely related to quantified psychological scale values (*F*(1, 16) = 4.90, *p* < 0.05). However, clear results were difficult to obtain due to the small difference

Latency changes in the left and right hemispheres indicated the presence of a significant difference between ASW (0.03) and ASW (0.45) only at N2 in the left hemisphere (*F*(1, 16) = 11.09, *p* < 0.05). The tendency of ASW (0.45) latency being smaller than ASW (0.03) latency in the left hemisphere can be seen from **Figure 9**, whereas in the right hemisphere, ASW (0.45) latency was consistently

(*F*(9, 2488) = 5.21, *p* < 0.001). However, no significant differences were observed in psychological reactions to speech intelligibility. A significant relation between articulation rates and the order of reactions was detected in the mean values related to the right hemisphere. Thus, left hemisphere showed changes in β-waves in relation to the order of delay time on reflection but speech intelligibility reactions.

detected in the articulation rate results related to "yu2," "he4," and "ian1." The 100 ms delay is close to the 135 ms slow response delay proposed in Ando's [22] study on sound field preferences (echo disturbance). The displeased response of α-waves to the delay time of reflection [14] requires further investigation.

to the influence of the delay time of reflection on the left hemisphere

**3.2 Changes in subjective perception of ASW and brainwaves**

between ASW (−0.16) and ASW (0.03).

**44**

**Figure 8.**

*Relationship between potential, SVR and ASW of sound field.*

The arrangements and results of the aforementioned brainwave experiments indicated that when simple physical changes in a sound field and complex psychological feedbacks affect cerebral brainwave reactions, the correspondence of the cerebral specialization theory with the results becomes very complicated. In general, in this study, the left hemisphere tended to be activated in both temporal and spatial aspects based on the sound field. When the participants' brainwaves were recorded during the judgment task, the brain activation in the right hemisphere tended to reflect the discriminated object more closely. When CBW were observed during research on speech intelligibility, the left hemisphere showed clear reactions to the first reflection delay time of sound field (**Figure 7**). However, the degree of speech intelligibility is a reflection of the complex thinking process that occurs in the right hemisphere (cerebral feedback). This phenomenon was supported by the subjective ASW experiment. With regard to changes in spatial factors, the left hemisphere received information

about sound field changes when the IACCE3 value changed. ASW changes between (ASW (0.03) and ASW (0.45)), which were more evident in the right hemisphere, affected both right and left hemispheres. They are coherent while the N2 latency of SVR significantly prolonged in both left and right hemispheres under changes of subjective diffuseness in IACCE3 found by Ando et al. [20]. Different sites are activated by brainwaves during focused and ambient use of the brain.

Cerebral specialization has been reported to be determined by focused conscious decisions. For instance, Floel et al. [23] conducted a spatial—visual focus experiment and used a Doppler ultrasound system and magnetic resonance imaging (MRI) equipment to observe the brain reactions of right-handed participants; the researchers found that both spatial recognition and speech functions were activated in the right hemisphere, which corresponded to clinical experiment results.

Nevertheless, for CBW researches, we conclude that α-waves (8–12 Hz) mainly responds to the emotional reactions; β-waves (13–30 Hz) reacts to the auditory matter drift (**Figures 6** and **7**). But the left hemisphere leads focus or attention on the varying of situational conditions (**Figures 8** and **9**), and the right one blends with imaginable feeling and experience. Hemispheric specialization has to pay attention to the conditioned response, conscientious and careful detail to setup each brainwaves' experiment.
