An objective noise-meter reading in phons for sustained noises, with special reference to engineering plant

The paper points out the desirability of objective as opposed to subjective noise-meters, but emphasizes that the reading of the objective meter must be in accord with the subjective standard, the phon. The limitations of the conventional objective noise-meter, corresponding to the American sound-level meter, are discussed and a new principle of noise measurement, involving a correction to be added to the conventional noise-meter, is described. The derivation of this correction from peak and r.m.s. readings is given, both ideally and practically, and performance figures substantiating the title ¿phon-meter¿ are included. Possible improvements in design are discussed.