Toward a More Musical Foghorn

Abstract

Ten college students gave preference judgments for 4 pure tones (120, 300, 500, and 835 IIz) and 11 tone composites constructed from combinations of the pure tones. Equal aversion (tolerance) levels were also measured for the four pure tones and for five of the composites. Sensation-level measures were employed to express aversion thresholds in order to take account of the differential sensitivity of the human ear at different frequencies. Certain operational conclusions were suggested for the design of acoustic navigation aids. The higher frequency pure tones and composites were generally more preferred, and were also tolerated at higher sensation levels. The 120-IIz pure tone was a highly non-preferred signal. The presence of a 120-Hz component in any composite lowered both the preference value and the maintained sensation level. In the case of the moderately preferred 500-Hz pure tone, adding other more-preferred, pure-tone components increased the preference for the signal.