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June, 1930] lyOUD SPEAKERS AND SOUND REPRODUCTION 617
steps on the average gain control and is consequently of minor importance.
Radiation Distribution Characteristics. — The radiation distribution characteristics of both types of speakers as now used are sufficiently good to yield satisfactory results. These distribution characteristics are fairly uniform through angles of about 20 degrees to each side of the normal to the mouth opening. In the average size of theater this is sufficient. In wider and larger houses, two or more speakers may be used, thus securing good directional characteristics as well as permitting an increase in the total amount of radiation as required by the larger size of the house.
Input Power Capacity. — No accurate measurements were made with respect to this quantity. However, it has been our observation that similar houses require the same number of speakers of either type for satisfactory sound reproduction. This indicates that, in view of the somewhat greater efficiency of the horn type speaker, the directional baffle type speaker has the edge in respect to input power capacity. This is what might be expected from the fact that the radiating surface of the directional baffle type speaker, i. e., a cone, is much sturdier than the fragile metal diaphragm of the horn type speaker.
RESULTS IN THEATERS
It is exceedingly interesting to compare the results obtained with both types of speakers on listening tests in theaters and see to what extent these results are explainable on the basis of the measurements described above.
Comparisons of this sort must be made separately for both speech and music.
If, in the reproduction of speech, we fix our attention upon the under 'standability only, we find that each of the loudspeakers is equally good. However, although speech on each of these speakers is equally understandable, the reproduction on the directional baffle type speaker is far more natural than on the horn type speaker. Reproduction on the horn type speaker has an unnatural quality. All voices sound very much alike whether of the same or opposite sex. Looking away from the screen makes it sometimes difficult to distinguish the sex, except from the context. Male voices, particularly, sound too high pitched and unnatural.
These results are easily explainable on the basis of the obtained frequency characteristics. It is well known that the elimination of