Journal of the Society of Motion Picture Engineers (1930-1949)

June, 1930] LOUD SPEAKERS AND SOUND REPRODUCTION 621 horns with a 57 cycle cut-off for three or four years. The fact that Mr. Maker's horn type cuts off at higher frequency than described in our paper leaves a question of whether he was considering a horn of the type which we discussed in our paper. MR. M ALTER: With regard to the open air characteristics of the microphone, I assume that Mr. Blattner refers to higher audible frequencies. Corrections were made on these characteristics. With regard to the second point on efficiency, the relative efficiencies as determined were in regard to frequency response, and the characteristics shown in the figure were obtained under conditions such as to enable an accurate frequency response comparison to be made. That was mentioned in the paper. With regard to the third point on input power capacity. I agree with Mr. Blattner that few measurements have been made by anyone in this respect, and in the conclusion we rate both on the same level with regard to input power capacity. Mr. Blattner states that the questions of the increase of efficiency due to combinations were brought out in the paper delivered in Toronto. I wasn't there, but I read and studied the paper carefully and don't recall any references to it in the paper. I should like to ask Mr. Blattner a question: He states that he has had a horn in his laboratory cutting off theoretically at 57 cycles; I should like to know where it actually cuts. MR. BLATTNER: You get loading of the diaphragm at about 50 per cent above the theoretical. MR. FLETCHER: With regard to the lowering of articulation which we were discussing, it is not very much, of course, if you take all speech sounds together, but there is an observable difference which is recorded in the book Mr. Malter mentions. Mr. MALTER: I agree with Mr. Fletcher, but the discussion was limited to the understandability of speech and the elimination of frequencies above 4000; although this may reduce the intelligibility of certain sounds, it doesn't in any particular manner lower the understandability of speech as a whole . MR. BLATTNER: May I refer Mr. Malter to the last paragraph of our paper with regard to the multiplicity of units on the horn type of speaker? MR. Ross: Mr. Malter stated that male voices have an average frequency of 128 and female voices 256, and that therefore a cut-off at 4000 cycles is immaterial. Male voices in song most nearly average 256 cycles and female voices 512 cycles. The harmonics consisting of the partials and their octave harmonics and the octave harmonics of the fundamental determine the beauty of the singing voice. Many of these harmonics lie above 4000 cycles. The horn type speaker producing an additional 1000 cycles is believed therefore to produce more faithful reproduction of voice in song if not in speech also. MR. MALTER: For correct reproduction we should reproduce all frequencies, and the greater the frequency range, the greater the naturalness. In that respect, as I pointed out, the directional type of speaker has the edge. MR. BRAUN: Were any tests made showing at what point either of the two types of speakers introduces distortion? MR. MALTER : No careful tests were made on that point. MR. LAWLEY : May I ask what the size of the final opening of this directional baffle was? MR. MALTER: Five feet by three feet.