Notes on Loud Speaker Response Measurements and Some Typical Response Curves

The difficulties encountered in loud speaker measurements are briefly reviewed and a description of the acoustic features of a particular indoor measuring system is given. Outdoor testing arrangements are described whereby double as well as single radiating loud speakers are measured with negligible ground reflection error. It is pointed out that the over-all electrical fidelity curve of a radio receiver is an inadequate performance index; the electro-acoustic fidelity embracing the frequency response of the loud speaker is suggested as more informative. The interpretation of loud speaker response curves in terms of what one may expect to hear is discussed. Reponse curves shown and discussed include the following: (1) Effect of type of cone corrugation. (2) Comparison of radio receiver cabinet with fiat baffle. (3) Curves showing that the face dimensions of a box baffle are of equal importance with the path length from front to rear of cone in determining low-frequency response. (4) The effect of extreme length in a box baffle. (5) Measurements of the same loud speaker in cabinets of different size. (6) Over-all electro-acoustic response curves of radio receivers. (7) Loud speakers with improved high-frequency response. (8) Some examples of outdoor measurements.