4. Research method[Reverberation time study according to cave structure]

4.1. Process

1. Set the area around 20~40m from the entrance of Hyeopjae Cave as a control group.

2. Take the 30m point from the entrance as the reference, and set the interval of 5m in front and behind the reference as the experimental section.

3. In order to find out the structure of the experimental section, check the shape with a laser range finder every 2m. At this time, the shape of each point can be inferred by measuring 19 times at 10° intervals.

4. After obtaining the data values, visualize the internal structure of the cave using Autodesk 3D CAD.

5. At the reference point of the experimental section, strike the tuning fork with the resonator of the tuning fork facing the ceiling.

6. At this time, experimentally measure the reverberation peak point and reverberation time using FrequenSee and Analyzer.

7. Analyze the reverberation time obtained based on the data to obtain the result value of the control group.

8. The experimental group repeats steps 1 to 7 in a different place from the control group to find out the reverberation time of the experimental group.

 

 

4.2. 유의사항

• When setting the control group and the experimental group, be careful not to create a self-curve with a tape measure. There is a high possibility of making mistakes because there is little light entering and exiting the cave during the experiment.
• When measuring an angle with a laser rangefinder, make sure that the body part of the person passing by or measuring the angle does not affect the measuring distance.
• Because there are many holes in the wall, an error may occur in the laser range finder. In this case, adjust it well so that the machine does not shake and measure again.
• When measuring the tuning fork, the error increases if there are many people around, so the number of people should be arranged as small as possible, and the posture should be so as not to affect the reverberation of the sound as much as possible.
• When analyzing data values, work after classifying the measured data values ​​by terrain to avoid mixing the data.