The impact of background speech varying in intelligibility: Effects on cognitive performance and perceived disturbance

Abstract

Noise abatement in office environments often focuses on the reduction of background speech intelligibility and noise level, as attainable with frequency-specific insulation. However, only limited empirical evidence exists regarding the effects of reducing speech intelligibility on cognitive performance and subjectively perceived disturbance. Three experiments tested the impact of low background speech (35 dB(A)) of both good and poor intelligibility, in comparison to silence and highly intelligible speech not lowered in level (55 dB(A)). The disturbance impact of the latter speech condition on verbal short-term memory (n=20) and mental arithmetic (n=24) was significantly reduced during soft and poorly intelligible speech, but not during soft and highly intelligible speech. No effect of background speech on verbal-logical reasoning performance (n=28) was found. Subjective disturbance ratings, however, were consistent over all three experiments with, for example, soft and poorly intelligible speech rated as the least disturbing speech condition but still disturbing in comparison to silence. It is concluded, therefore, that a combination of objective performance tests and subjective ratings is desirable for the comprehensive evaluation of acoustic office environments and their alterations.

Algorithmic modeling of the irrelevant sound effect (ISE) by the hearing sensation fluctuation strength

“…A combined reduction of speech level and intelligibility reduced error rates; however, the algorithm expected still more errors than during the silent control condition as was observed in the performance experiment (cf. Schlittmeier et al, 2008c).…”

“…However, even for background speech, applying fluctuation strength might be of greater precision than applying the STI in certain cases. For example, the STI cannot adequately estimate the intelligibility of extremely low-pass filtered and low-level speech signals as tested by Schlittmeier et al (2008c). In this study, the level of speech was reduced to 35 dB(A) either in a broadband filter condition (speech intelligibility remained high) or in a lowpass filter condition with 60 dB(A) attenuation around 4,000 Hz (low speech intelligibility), and verbal short-term memory was measured in these background speech conditions.…”

“…1 must be evaluated separately in the different critical frequency bands. These different estimates then must be integrated, considering the boundary condition that a stimulus with 1 kHz and 60 dB (which is fully amplitude modulated at 4 Hz) yields a fluctuation strength of F = 1 vacil (vacil denotes the entity of fluctuation strength as defined by Fastl, 1983 (Schlittmeier & Hellbrück, 2009;Schlittmeier et al, 2008aSchlittmeier et al, , 2008bSchlittmeier, Hellbrück, Thaden, & Vorländer, 2008c) or in full congress contributions (Schlittmeier & Hellbrück, 2004;Schmid & Hellbrück, 2004). Furthermore, only few data were obtained from unpublished diploma or doctoral theses (Hauser, 2005;Schlittmeier, 2005), or have not yet been published.…”

Effect of self-adjustable masking noise on open-plan office worker’s concentration, task performance and attitudes

“…Finally the questionnaires utilised in our study were susceptible to being biased by the participant subjective impressions of the task being considered. The use of objective performance tests would have provided additional data to verify the results of the questionnaire (Schlittmeier, et al 2008). …”

The Effect of Background Music on the Visual Categorization of Printed Words in Normal Younger and Older Adults

“…Contributions to the degree of semantic processing can come from allocating either voluntary or involuntary attentional resources to the background music as well as from semantic processing required by a cognitive task. Past auditory-visual dual-processing task studies analyzing the effect of listening to a meaningful auditory stimulus or background music have noted detrimental effects on reading comprehension (Oswald, Tremblay, & Jones, 2000;Sörqvist, Halin, & Hygge, 2010), memory recall (Enmarker, 2004;Schlittmeier, Hellbrück, Thaden, & Vorländer, 2008), and proofreading (Jones, Miles, & Page, 1990;Venetjoki, Kaarlela-Tuomaala, Keskinen, & Hongisto, 2006) tasks. However, a similar investigation of a visual semantic word categorization task has not yet been undertaken.…”