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Highly intelligible background speech of 55 dB(A) impairs cognitive performance

Reported live from ICA Madrid

DSCN0050.jpg Sabine Schlittmeier

Sabine Schlittmeier, psychologist at Eichstätt University in Germany, presented her paper called Background speech varying in intelligibility – Effects on coginitive perfromance and perceived disturbance. Sabine presented three experiments, which tested the impact of background speech varying in intelligibility and/or level on basic cognitive functions (verbal short-term memory, sustained attention, verbal-logical reasoning).

Listen to the interview. (preferably use loudspeakers or earphones)

The results show that highly intelligible background speech of 55 dB(A) impairs cognitive performance. In order to diminish its disturbance impact significantly, a sole level reduction is not enough – an additional reduction of speech intelligibility is necessary. Subjective disturbance ratings, however, value lowering of the background speech’s level to a greater extent than reducing its intelligibility. Furthermore, although cognitive performance coincided during soft and poorly intelligible speech with those during silence, it was still rated as significantly disturbing.
Thus, the experiments demonstrate that objective performance tests and subjective ratings
complement but cannot substitute each other with regard to a comprehensive evaluation of
acoustic office environments and their alterations.


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