ACOUSTIC RATIO

A system of gears which alter the ratio between the revolution of the engine and the propeller shaft so the propeller operates in a relatively efficient speed range. By using a gearbox the engine and the propeller shaft will revolve at different speeds.

1. An increase in signal magnitude from one point to another, or the process causing this increase.
2. Of a transducer, the scalar ratio of the signal output to the signal input

1. The ratio of radiated sound intensity at a remote point on the principal axis of a loudspeaker or other transducer, to the average intensity of the sound transmitted through a sphere passing through the remote point and concentric with the transducer; the frequency must be stated.
2. The ratio of the square of the voltage produced by sound waves arriving parallel to the principal axis of a microphone or other receiving transducer, to the mean square of the voltage that would be produced if sound waves having the same frequency and mean-square pressure were arriving simultaneously from all directions with random phase; the frequency must be stated.

1. The ratio of the effective value of a periodic function, such as an alternating current, to its average absolute value.
2. A factor that takes the shape of a coil into account when computing its inductance. Also known as the shape factor.
3. The theoretical stress concentration factor for a given shape, for a perfectly elastic material.