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

620 Louis MALTER [J. S. M. P. E. MR. RYDER: The tests Mr. Malter mentioned were based on the placing of the microphone on the earth, which may be more suitable for one speaker than for another because of the type of the horn. Was the method of test partial to one or other of the types? MR. MALTER: The type of measurements has nothing to do with the horns. The method was the best way of obtaining the characteristics of any loud speaker of that size. MR. FLETCHER: The first question I want to ask is whether these measurements were made on just one horn type and one baffle type, or were ten or twenty used? I know that we have found the variation from one type to another is almost as much as was shown. Why did you pick the particular ones you did? The second question is, on what was your statement based that one had better naturalness? Was it a matter of opinion or were measurements made? The third question concerns the statement that you get the same understandability of speech because the frequency response between 300 and 4000 is the same. We have made measurements on this which show there is a difference in the understandability of speech, so that if the tests were made carefully that would have been shown by articulation tests. MR. MALTER : To answer the first question as regards the number of speakers, employed in the tests : these chosen were chosen by listening tests of these types all of which gave practically the same quality of reproduction. As regards the point as to which types were chosen, we chose the speakers of each type most widely used in the theaters and not those having a relatively small distribution. As regards the question on the subject of naturalness, this is a factor which is to a large extent subjective. Measurements of this factor cannot be made very accurately in an objective fashion, and the conclusion as to naturalness is the result of the impartial observations of a large number of observers. With regard to articulation, the measurements do indicate practically identical articulation. The effect of frequencies of 4000 cycles is not in agreement with the results published by Mr. Fletcher in his book on "Speech and Hearing." MR. BLATTNER: May I ask if the frequency characteristic curves have been corrected for the open air transmission characteristic of the microphone used in making the measurements? Another point with regard to efficiency: at a frequency of about 2000 cycles a difference between the two curves was shown of something greater than 2 decibels, and if I understood the author correctly, the baffle speaker would be louder than the horn at that range. This difference in efficiency is somewhat different from the impression we have had from different types and numbers of speakers of both kinds, and we should like further information. The horn speaker is a little more efficient than was indicated. I believe that with the metal diaphragm in the horn type, the power capacity is not a problem although there are few data available with regard to this point. We know there is little difference. With regard to Mr. Malter's reference to our paper of last fall, most of the questions brought out by Mr. Malter were discussed in the paper. The question of response in using two or more baffle speakers was explained. The effect is limited to the lower frequencies, and this can be improved in the horn type by designing two separate horns to be combined. With regard to the practicability of using the horns at lower frequency, as described in our paper, this is quite practicable because we have been using