Distance Estimation of 0° or Apparent 0°-Oriented Speech Signals in Anechoic Space
Mark B. Gardner · The Journal of the Acoustical Society of America · 1969
This paper reports the results of tests of the ability of an observer to estimate the distance of speech signals that originate, or appear to originate, at the intersection of the horizontal and median planes in anechoic space. Both live and recorded sources were used over a range of distances from 3 to 30 ft. For such a range (i.e., where differences in the selective effect of air absorption with frequency are relatively small), the results showed a wide difference in observer ability to estimate the distance for these two types of sources. When loudspeaker sources of recorded speech were employed, the judgments reported were essentially independent of the actual distance involved. This was true whether single, multiple symmetrical, or asymmetrical arrays were employed. When a live voice was used as a source, a rather marked degree of ability to estimate relative distance was found depending on the type of vocal output employed and on the degree to which normal level changes with distance were eliminated as a parameter. Use of a shouted voice resulted in overestimating the distance, whereas the apparent distance was foreshortened when a whispered voice was employed.