Han Myong U, a researcher at the Faculty of Communication, has been making achievements by employing a self-designing experimental method in experimental education whereby students can design the whole process from the idea of a device to its manufacture and do measuring experiments by themselves.
The subject “electroacoustic engineering” is the study on principles and methods to turn electrical energy into acoustic energy and vice versa, and also to implement its acoustic systems.
In the past experimental teachings, students failed to have a good understanding of the overall experimental process as they followed the fixed orders and methods, and also they revealed a lack of skills in analysing why the experimental results were different from theories and in working out how to deal with it due to the fact that almost all results were apparent and predictable.
In order to fix these problems, he has applied a self-designing experimental teaching method, whereby students can design by themselves the overall process from the plan for device-manufacturing to its implementation and then do measuring experiments, to experimental teachings, thus achieving a series of successes.
First, he gave experimental tasks to students for designing the most adaptable experimental instruments and measuring frequencies in their own way in parallel with recollecting carefully what they already learnt.
The tasks were supposed to have various choices of experimental objects and various plans of experimental processes, and to have different results according to their own plans and performances.
For example, during the experiment on the evaluation of the directivity characteristics of speakers, the tasks such as “Please select the worst and best speakers in terms of cross modulation and compare them.” and “Please select the speaker with the narrowest directivity and the one with steady directivity in a high-frequency band and compare them.” can lead the students to acquire the several characteristics of speakers and their measuring principles that are being widely considered in reality.
Through these tasks, the students are able to acquire more profound knowledge about the characteristics of several kinds of speakers by revising sufficiently what they have already learnt ranging from the selection of available speakers and microphones for experiments to the selection of measuring frequencies and the interval of measuring angles for clear comparison and analysis as well as by reading references intensively.
Second, he has motivated students to design by themselves the experimental processes before conducting simulations with simulation tools in order to compare and analyze the results.
After making clear the overall plan for the experimental process, they can go deep into a detailed study in order to obtain as much correct measurement data as possible within the limited time.
For example, in an experiment on the directivity characteristics of a speaker, they can make a detailed design of how to determine the space of experimental tables, how to measure the next frequency after rotating them by 180 degrees, whether to keep measuring after returning to the initial coordinate, and whether to do all measuring experiments on several frequencies at the same angle, and then prepare for the experiment according to the design.
After that, they can decide whether or not the simulation methods and elements they selected are suitable and their measuring frequencies are most reasonable.
For the simulation of speakers, students commonly use simulation software for directivity. In this case, they conduct a dynamic simulation based on the detailed geometrical sizes and values of speakers selected by them.
While analysing the correctness of the plan they selected and the reasons for false choice, they get to study continuously how to make a simulation closer to the reality by confirming the experimental plans they have made and changing the experimental design to a certain degree if necessary.
Thus, he was able to enhance students’ cognition in class by building up their creative thinking ability, and additionally to equip them with practical and technical skills for designing, simulating and analyzing the electrical acoustic instruments on their own.
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