Target identification using relative level in multi-talker listening

Previous studies have suggested that listeners can identify words spoken by a target talker amidst competing talkers if they are distinguished by their spatial location or vocal characteristics. This direct identification of individual words is distinct from an indirect identification based on an association with other words (call-signs) that uniquely label the target. The present study assessed listeners' ability to use differences in presentation level between a target and overlapping maskers to identify target words. A new sentence was spoken every 800 ms by an unpredictable talker from an unpredictable location. Listeners reported color and number words in a target sentence distinguished by a unique call-sign. When masker levels were fixed, target words could be identified directly based on their relative level. Speech-reception thresholds (SRTs) were low (-12.9 dB) and were raised by 5 dB when direct identification was disrupted by randomizing masker levels. Thus, direct identification is possible using relative level. The underlying psychometric functions were monotonic even when relative level was a reliable cue. In a further experiment, indirect identification was prevented by removing the unique call-sign cue. SRTs did not change provided that other cues were available to identify target words directly. Thus, direct identification is possible without indirect identification. (C) 2013 Acoustical Society of America.