*3.1.2 Methodology of experiment 1*

Our proposed evacuation guidance system help evacuee realize the path to the exit using sequence of acoustic stimuli emitted thought several loudspeakers which were arranged on the ceiling of buildings. In the first experiment loudspeakers were arranged in a 5 × 5 grid 4 m above from floor level in the gymnasium of Hanna University. The experimental environment and the arrangement of the loudspeakers are illustrated in **Figures 1** and **2**. The numbers rounded with squares in **Figure 2** are the index of loudspeakers.

During the experiment, the subjects stood in one of two possible positions, just below loudspeaker 13 or between loudspeakers 13 and 17. The loudspeakers were a

#### **Figure 1.**

*Experimental environment and the arrangement of the loudspeakers.*

#### **Figure 2.**

*Arrangement of the loudspeakers, subjects' position, and sequential pattern of sound stimuli in the first experiment.*

capacitor-type flat speakers with stronger directionality than conventional dynamic speakers. We used a switching device with a small controller (Arduino Uno) that could be controlled by the software to emit the sound stimulus on all 25 loudspeakers in a sequence for specific time intervals. The sound stimulus level was set for each stimulus type (voice or swept-sound), such that the A-weighted noise level was 80 dB at a position 1 m from the loudspeaker. The noise level was measured using an integrated average-type sound-level meter (LA-1441, Ono Sokki Co., Ltd.).

In the first experiment, the sound stimulus (the voice or swept-sound) was emitted sequentially through five loudspeakers. For example, it is the sequence from loudspeakers 1–21 in the order of 1, 6, 11, 16, 21 in a straight line shown by an arrow in **Figure 2**. All 12 distinct sequence patterns of the sound stimuli (including five row-wise ones (left-to-right or right-to-left), five column-wise ones (front-to-back or back-to-front), and two diagonal ones (front-to-back or back-to-front) are shown by an arrow in **Figure 2**. Considering that the sequences were emitted in both ascending and descending order, there were totally 24 sequence patterns. For example, the emitting sequence in ascending order was set to five straight line patterns: numbers 1–5, 6–10, 11–15, 16–20, and 21–25.

The subjects were instructed to listen to the sequence at a specific position (as mentioned earlier, position just below loudspeaker 13 or the other) and identify the sequence pattern as quickly as possible. We conducted a trial for each subject to listen to the sound stimuli and answer which patterns were emitted before conducting the first experiment. The first experiment, in which the 24 sequence patterns were emitted randomly in each trial under different conditions (combining the four factors) was then conducted. The sound stimulus continued until the subjects returned their answer. Sixteen trials under each experimental condition combining the four factors were conducted for each subject repeatedly because four two-level experimental factors were considered in this experiment. An experimenter recorded the participants' response time and the accuracy of their answers (accuracy rate).

#### *3.1.3 Experimental results and discussion for experiment 1*

### *3.1.3.1 Experimental results regarding each factor*

**Figure 3** shows the mean accuracy rates and response times of identification of emitting sequence regarding four experimental factors. We conducted a three-way analysis of variance (ANOVA) to compare the mean-accuracy rates and response times, considering three within-subject factors: stimulus type, emission-time interval, and the distance between loudspeakers.

In the ANOVA results for accuracy rate, significant differences were observed for both stimulus type (*p* = 0.01) and emission interval (*p* < 0.01). Similarly, in the ANOVA for the response time, a significant difference was observed in the stimuli type (*p* < 0.001). Furthermore, an interaction was observed between the emission interval and the distance between the loudspeakers (*p* < 0.001). Thus, the results of ANOVA for accuracy rate and response time indicate that the sequence of voice stimuli emitted at 1.0 s interval is better than the other sequence.

The influence of four factors on the identification of sequence pattern of sound stimuli was evaluated through the experiment. The overall identification rate was over 80% across 24 sequence patterns. Comparing four factors affecting the accuracy and response time, the significant effects with respect to the type of sound source and the emission-time interval was confirmed. The type of sound source had a particularly strong effect for the results. The accuracy rate of identification was higher, and the response time was shorter when the voice sound emitted as acoustic stimuli than the swept-sound. These results suggest that the use of voice rather than swept-sound as a sound source enables the correct recognition of the direction of guidance.

*Evacuation Guidance Assistance System Using Emitting Sound DOI: http://dx.doi.org/10.5772/intechopen.105223*

#### **Figure 3.**

*Mean accuracy rates and response times regarding experimental factors. (From Miyoshi [6]). (a) Mean accuracy rates and response times regarding stimulus type. (b) Mean accuracy rates and response times regarding the distance between loudspeakers. (c) accuracy rates and response times regarding interval between sound stimuli. (d) Mean accuracy rates and response times regarding subject's standing point. p < 0.001: \*\*\*, p < 0.01: \*\*, p < 0.05: \*.*

Aoki conducted the sound localization experiments for middle-aged and elderly subjects using multiple sound sources including voice as acoustic stimuli. As the results it was reported that the incorrect response rate was lowest, and the reaction

time was shortest when vocal stimuli were used [13]. Thus, we could easily perceive the vocal phrase and identify its localization. Our experiment task was the identification of the sequence of emitting sound source, and the performance of task become higher for voice stimuli due to the ease of sound location for it.

The differences in the accuracy rates and response times classed according to the different emission-time intervals (1 and 0.5 s) are summarized in **Figure 3b**). The mean-accuracy rate for both sound stimuli emitted in the interval 1 s was higher than in interval 0.5 s, although there was not a significant difference in response time between both intervals. These results indicate that the stimulus sequence can be identified more easily when the emission-time interval is 1 s.

### *3.1.3.2 Experimental results with respect to identification of sequence patterns*

The accuracy rates and response times of the subjects were compared among sequence patterns, such as row-wise and column-wise sequences. **Figure 4a** and **b** illustrate the mean accuracy rates and response times for the row-wise sequence patterns and the left-right direction, respectively. A two-way ANOVA was conducted to detect whether there were statistically significant differences in the mean scores regarding the five row-wise sequence patterns and the left-right directions, considering within-subject factors. It was confirmed that there were the significant differences in the main factor (row-wise sequential pattern) for both the accuracy rate (*p* < 0.001) and response time (*p* < 0.001), but there was no significant difference in the main effect regarding the direction and the interaction of two factors.

Bonferroni's multiple comparison (comparison count: 10 times) of the accuracy rate and response time among the 5 stimulus sequences was conducted and its results were shown in **Table 1a**. The accuracy rate for the row-wise sequence from 11 to 15 was the highest and response time is shortest among the row-wise ones. This result suggests that it is easier to identify the sequence that pass the subject standing point, the loudspeaker 13 and the identification performance became higher as the distance to the sound sequence from subject decreases.

In the same way as row-wise patterns, **Figure 4c** and **d** illustrate the mean accuracy rates and response times for the column-wise patterns and the direction from front/behind, respectively. The two-way ANOVA also were conducted for the mean scores regarding the sequence patterns and the direction. It was confirmed that the significant differences regarding main effect of sequence pattern were detected in both the accuracy rate (*p* < 0.001) and response time (*p* < 0.001) for the column-wise sequence. Additionally, there were the weak significant effect regarding the direction on the accuracy rate (*p* = 0.078) and the strong significant effect on the response time (*p* = 0.0068), but the interaction was not detected. Results of Bonferroni's multiple comparison (comparison count: ten times) of the accuracy rate and response time regarding the column-wise sequences pattern is shown in **Table 1b**.

The accuracy rate for the sequence from 3 to 23 was the highest and the response time is shortest among the column-wise ones. In the same as results regarding the row-wise sequence, it is easier to identify the sequence that pass the subject standing point, the loudspeaker 13 and the identification performance became higher as the distance to the sound sequence from subject decreases. However, the performances (accuracy rate and response time) for the sequences in the second and fourth line were as well as the third centered line. These results suggest that there may be a range in which people could properly identify the location and the direction of the sound sequence.

*Evacuation Guidance Assistance System Using Emitting Sound DOI: http://dx.doi.org/10.5772/intechopen.105223*

#### **Figure 4.**

*Mean accuracy rates and response times for horizontal and vertical patterns in a straight line. (a) Mean accuracy rates regarding row-wise pattern from left and right. (b) Mean response times regarding row-wise pattern on the left and right hand sides. (c) Mean accuracy rates regarding column-wise pattern from left and right. (d) Mean response times regarding column-wise pattern from left and right. (From Miyoshi [6]).*


#### **Table 1.**

*Results of Bonferroni's multiple comparison for accuracy rates and response times in cases of row-wise and column-wise patterns.*

## **3.2 Identification of sound emitting in right-angle sequences**

The first experiment investigated the identification performance of the subjects for the straight sequence of the emitted sound. The actual evacuation paths to exit include the straight and right-angle paths. For example, an evacuee evacuates from the inside of a building to the outside by going straight and turning. The identification performance for the emitting sound in right-angle sequences must be evaluated to ensure that the proposed guidance system works effectively in the event of a disaster. In this section, we summarized the second experiment to evaluate the performance of identification for right-angle sequences based on a reference [6].

### *3.2.1 Methodology of experiment 2*

In the second experiment, the sequence of sound stimuli was generated in the same experimental environment with the first experiment as shown in **Figure 1**. Twenty-five loudspeakers were arranged in a 5 × 5 grid 4 m above from floor level. For this experiment, the distance between the loudspeakers was fixed at 3 m to compare the emission patterns of the straight and right-angle lines. Considering the three experimental factors: sequence shape (two levels of straight and right-angle sequences), stimulus type (voice and swept-sound), and emission-time interval (0.5 and 1 s), the experiment was conducted to assess whether or how these factors affect identification of the sound sequence. The second experiment was conducted under eight experimental conditions, including all combinations of the above three factors. In each trial, sound stimuli were emitted in four right-angle and two straight-line sequences. In addition, the both directionalities of all the sequences, front-to-back one and back-to-front one, were considered, as illustrated by green and bidirectional arrows in **Figure 5**.

*Evacuation Guidance Assistance System Using Emitting Sound DOI: http://dx.doi.org/10.5772/intechopen.105223*

**Figure 5.**

*Arrangement of audio loudspeakers, subject position, and sequential pattern of sound stimuli in the second experiment.*

The subjects were instructed to stand at a specific position near by the loudspeaker 23 and listened to and identified the sequence pattern as quickly as possible. The sound sequences were randomly selected from 12 possible sequential patterns and start position of sound sequence was determined randomly. The sound stimulus continued until the subjects returned their answer. An experimenter recorded the participants' response time and the accuracy of their answers (accuracy rate). The subjects of the second experiment were seven male students (20–21 years old) who had participated in the first experiment.
