# Effects of Auditory Pre-Stimulation on Cognitive Task Performance in a Noisy Environment
## 3 Results and Discussion
### Experiment 2
#### 3.2.2 Discussion  
In _Experiment 2_, each participant performed the three STM/WM tasks for four experimental conditions (\(\mathbf{P_{Q}}\,\mathbf{E_{F}}\), \(\mathbf{P_{W}}\,\mathbf{E_{F}}\), \(\mathbf{P_{F}}\,\mathbf{E_{F}}\), and \(\mathbf{P_{M}}\,\mathbf{E_{F}}\) ) to examine the effects of auditory pre-stimulation on the performance of basic STM/WM tasks in \(\mathbf{E_{F}}\). For the Digit span task scores, planned comparisons that compared the baseline condition \(\mathbf{P_{N}}\,\mathbf{E_{F}}\) with the other four experimental conditions revealed a significant difference only between the \(\mathbf{P_{N}}\,\mathbf{E_{F}}\) and \(\mathbf{P_{M}}\,\mathbf{E_{F}}\) conditions; the \(\mathbf{P_{M}}\,\mathbf{E_{F}}\) condition showed a 17.9% larger mean than \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Measure**Condition & \(\mathbf{P_{N}}\,\mathbf{E_{F}}\) & \(\mathbf{P_{Q}}\,\mathbf{E_{F}}\) & \(\mathbf{P_{W}}\,\mathbf{E_{F}}\) & \(\mathbf{P_{F}}\,\mathbf{E_{F}}\) & \(\mathbf{P_{M}}\,\mathbf{E_{F}}\) \\ \hline \multicolumn{6}{c}{**STM/WMTask Score**} \\
**Corsi block-tapping** & 4.63 (1.05) & 4.79 (0.58) & 4.42 (1.21) & 4.67 (0.76) & 4.42 (1.13) \\
**Digit span** & 6.75 (2.50) & 6.50 (2.46) & 6.58 (2.87) & 7.54 (2.30) & 7.96 (1.82) \\
**3-back** & 1.83 (1.23) & 1.88 (1.07) & 1.92 (1.05) & 1.83 (1.00) & 1.96 (0.95) \\ \multicolumn{6}{c}{**Mental Workload**} \\
**Corsi block-tapping** & 1.12 (0.90) & 1.45 (1.61) & 1.50 (1.98) & 1.70 (1.45) & 1.91 (1.79) \\
**Digit span** & 3.00 (1.47) & 3.87 (2.07) & 3.91 (2.26) & 3.62 (1.63) & 3.66 (2.39) \\
**3-back** & 4.20 (2.02) & 5.45 (2.39) & 5.12 (2.64) & 5.16 (2.40) & 5.16 (2.79) \\
**Overall** & 3.37 (1.49) & 4.25 (1.67) & 4.04 (2.19) & 3.83 (1.71) & 3.83 (2.23) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The mean and standard deviation values of all dependent variables for each experimental condition in _Experiment 2_. Figure 7: The mean and standard deviation values of mental workload experienced while performing the digit span task. the \(\mathbf{P_{N}}\mathbf{E_{F}}\) condition, confirming that mixed noise was effective as a type of auditory pre-stimulation (Figure 6). These results are in good agreement with those of [PERSON] et al. [55], who confirmed that the effects of office noise can be reduced by prior exposure to this type of noise. Interestingly, the mean score on the Digit span task in the experimental condition of \(\mathbf{P_{M}}\mathbf{E_{F}}\) was identical to that in \(\mathbf{P_{N}}\mathbf{E_{Q}}\), which was adopted as the environment for measuring the basic cognitive ability of each participant in _Experiment 1_ (Figures 4 and 6). Given that \(\mathbf{P_{N}}\mathbf{E_{F}}\) showed a 15.2% smaller mean than \(\mathbf{P_{N}}\mathbf{E_{Q}}\), the observed results would suggest that if _Mixed noise_ is provided in advance, cognitive task performance degradation due to _Field-noise_ Environment can be restored to a level equivalent to the basic competency of each individual. Another interesting finding was that while \(\mathbf{P_{M}}\mathbf{E_{F}}\) showed a significantly larger mean than \(\mathbf{P_{N}}\mathbf{E_{F}}\) for the Digit span task scores (Figure 6), no significant difference was found in the mental workload score (Figure 7). This is thought to be due to the fact that the task execution time in _Experiment 1_ and _Experiment 2_ differed from each other at two minutes and 30 s and seven minutes and 30 s, respectively, depending on whether or not auditory pre-stimulation (five-minute time duration) was presented. In relation to this, some studies have shown that an increased task duration increased the mental workload [84, 85]. Given the beneficial effects of auditory pre-stimulation, future studies can devise an accurate measurement method of the mental workload experienced only during the main task. To further investigate the relative excellence of _Mixed noise_ as a type of auditory pre-stimulation, an additional one-way repeated-measures ANOVA was conducted on an ad hoc basis.