Educational screen & audio-visual guide (c1956-1971])

recording, he pulls his switch back to 'Listen'. The i)ilot light in his booth and the light for his position on the teacher's console go out. If the stop-start switch has been set at 'Auto-Stop', each tape will stop automatically when the end of the loop is reached. In order to start the next phase of the lesson, the teacher must push the switch to 'Start'. Before he does this, he may make comments about the performances. During the next phase, each student hears a playback of his individual recording, which includes a copy of the master-recording, his responses, and any comments made by the teacher. As he listens, he can compare his responses with the master-recording and note any discrepancies. He can evaluate his responses by using the criteria supplied by the teacher, thereby recognizing his own mistakes. The instructor can also monitor during this phase of the lesson and speak to any student individually, as before, but his comments will not be recorded. When all tapes have stopped, the instructor can have the students repeat the cycle or he can conduct the rest of the lesson as he would in an ordinary class room. The system is very flexible, as one can see from the description given above. Additional flexibility is provided by an auxiliary input jack that makes it possible to connect a standard tape recorder, record player, radio, or sound track of a motion picture to the system. The laboratory may also be used by the students for practice sessions. In this case, each of the eight master channels can be used for a different master-recording, so that eight groups can work simultaneously. A number of students can work on individual assignments at the same time. This system is the result of careful study of the special requirements that an electronic language laboratory system must meet. While it is true that the Linguatrainer comes closer to satisfying these needs than many other sytems, more research is needed. One of the problems that requires special attention is that of determining the optimum frequency response of language laboratory equipment. Work in speech perception of speech transmitted over voice communication has shown that perception of speech transmitted over voice communication systems is affected by the bandwidth of the system." As the higher frequencies are eliminated, the speech becomes less intelligible; that is, there is more confusion of one sound with another because information necessary for identification of certain features has been eliminated. Furthermore it is possible to determine at what frequency levels various phonetic features disappear. Heretofore almost all of the work on speech perception has been done with subjects who were native speakers of the language that was transmitted. In language laboratories, we are not concerned with the perception of contrasts in speech by native speakers. It is possible, therefore, that "A more detailed discussion of some of these problems can be found in An Analysis of Perceptual Confusions Among Some English Consonants, George A. Miller and Patricia Nicely, lournal of the Acoustical Society of America, Vol. 27, No. 2, pp. 338-352, March 19.55. The remote control tape unit. This instrument, kept in an adjoining room, contains 30 dual track tape recorders. the results of previous studies are not applicable to the determination of electronic specifications for language laboratory equipment. A non-native speaker may need more information in order to identify sounds than does the native speaker. It is probably true, however, that even for nonnative speakers, increasing the bandwidth beyond a certain point does little to reduce the confusion of one, sound with another. The prob' lem in designing language laboratory equipment is therefore to define the optimum bandwidth for the system. It is easy to see that this problem is important, for high fidelity equipment is expensive. But if such equipment is necessary for effective learning, money spent for less expensive systems that do not i^rovide an adequate frequency response is wasted. Because of its importance, an investigation of the problem has been started at M.I.T. The research, supported by a grant from Educational Facilities Laboratories, a Ford Foundation agency, will be conducted over a two-year period by the author. It is the first step in the development of a research program which, it is hoped, will continue to test the application of recent advances in linguistic theory to the special problems of language teaching. 178 Educational Screen and Audiovisual Guide — April, 1960