Listening to Differentially Filtered Competing Voice Messages
Walter Spieth, John C. Webster · The Journal of the Acoustical Society of America · 1955
An attempt was made to improve listeners' ability to respond to one of two or more simultaneous or overlapping voice messages by differentially filtering the competing message channels. The limits of satisfactory intelligibility of two digits and two International Civil Aeronautics Organization (ICAO) phonetic alphabet words in a message also containing an address were determined under various conditions of high- and low-pass filtering and speech-to-noise ratios (S/N). Within these limits, several amounts of filtering were tried in various combinations. When performance on differentially filtered competing messages was compared with performance on unfiltered competing messages, it was found that differential filtering almost always improved performance. This was true regardless of whether it was the desired message that was filtered or whether it was one or more of the competing messages that was filtered, and the degree of filtering was relatively uncritical. High-pass cutoffs of 565, 800, or 1130 cps were about equally effective and were considerably better than high-pass cutoffs at or below 280 cps. Low-pass cutoffs of 1600, 1130, and 800 cps also improved performance substantially.