  A multi-talker paradigm is introduced that uses different attentional
processes to adjust speech recognition scores with the goal to conduct
measurements at high signal-to-noise ratios. The basic idea is to simulate a
group conversation with three talkers and a participant. Talkers alternately
speak sentences of the German matrix test OLSA. Each time a sentence begins
with the name "Kerstin" (call sign), the participant is addressed and
instructed to repeat the last words of all sentences from that talker, until
another talker begins a sentence with "Kerstin". The alternation of the talkers
is implemented with an adjustable overlap time that causes an overlap between
the call sign "Kerstin" and the target words to be repeated. Thus, the two
tasks of detecting "Kerstin" and repeating target words are to be processed at
the same time as a dual task. The paradigm was tested with 22 young
normal-hearing participants for three overlap times (0.6 s, 0.8 s, 1.0 s).
Results for these overlap times show significant differences with median target
word recognition scores of 88%, 82%, and 77%, respectively (including call sign
and dual task effects). A comparison of the dual task with the corresponding
single tasks suggests that the observed effects reflect an increased cognitive
load.
