  The irrelevant sound effect (ISE) characterizes short-term memory performance
impairment during irrelevant sounds relative to quiet. Irrelevant sound
presentation in most laboratory-based ISE studies has been rather limited to
represent complex scenarios including open-plan offices (OPOs) and not many
studies have considered serial recall of heard information. This paper
investigates ISE using an auditory-verbal serial recall task, wherein
performance was evaluated for relevant factors in simulating OPO acoustics: the
irrelevant sounds including the semanticity of speech, reproduction methods
over headphones, and room acoustics. Results (Experiments 1 and 2) show that
ISE was exhibited in most conditions with anechoic (irrelevant) nonspeech
sounds with/without speech, but the effect was substantially higher with
meaningful speech compared to foreign speech, suggesting a semantic effect.
Performance differences in conditions with diotic and binaural reproductions
were not statistically robust, suggesting limited role of spatial separation of
sources. In Experiment 3, statistically robust ISE were exhibited for binaural
room acoustic conditions with mid-frequency reverberation times, T30 (s) = 0.4,
0.8, 1.1, suggesting cognitive impairment regardless of sound absorption
representative of OPOs. Performance differences in T30 = 0.4 s relative to T30
= 0.8 and 1.1 s conditions were statistically robust. This emphasizes the
benefits for cognitive performance with increased sound absorption, reinforcing
extant room acoustic design recommendations. Performance differences in T30 =
0.8 s vs. 1.1 s were not statistically robust. Collectively, these results
suggest that certain findings from ISE studies with idiosyncratic acoustics may
not translate well to complex OPO acoustic environments.
