Research has shown impairing effects of irrelevant speech on cognitive capabilities as, for example, reading and listening comprehension. Yet, so far research has paid little attention to how these distracters can influence text production. The aim of this study is to investigate how speech intelligibility in terms of different Speech Transmission Index (STI) values influence writing performance. The expectation is that background sound with higher STI values (i.e., when it is easier to hear what is said in the speech signal) will be more detrimental to the writing process. Moreover, the expectation is that persons with high working memory capacity (WMC) will be less distracted than persons with low WMC. In an experimental within-subjects design college students (N ~ 48) are asked to write short essays (5 minutes per essay) in the software program ScriptLog in 5 different STI conditions. Across the conditions, irrelevant background speech masked by white noise is manipulated in terms of different STI values. The essays are based on different pictures presented on a computer screen. At the beginning the participants are asked to do a working memory task (size-comparison span). The results will be presented at the conference. This study contributes to further knowledge of how different acoustical conditions influence cognitive language production processes, which is important in schools and office environments.