Irrelevant Background Speech Research Articles

Akustisch optimierte Arbeitswelten

Acoustically optimized working environments: Strategies to increase productivity, comfort and attractiveness In open office structures, noise is still a widespread source of dissatisfaction, annoyance, disruption and stress. The well-documented effects of noise in research, such as the “irrelevant speech effect”, i.e. the disruption of cognitive performance due to irrelevant background speech, can be found in practice as central challenges of acoustic design. Five aspects are presented below that should definitely be considered when planning and optimizing acoustics – for greater satisfaction, well-being and productivity in the office.

Attention to audiovisual speech shapes neural processing through feedback-feedforward loops between different nodes of the speech network.

Selective attention-related top-down modulation plays a significant role in separating relevant speech from irrelevant background speech when vocal attributes separating concurrent speakers are small and continuously evolving. Electrophysiological studies have shown that such top-down modulation enhances neural tracking of attended speech. Yet, the specific cortical regions involved remain unclear due to the limited spatial resolution of most electrophysiological techniques. To overcome such limitations, we collected both electroencephalography (EEG) (high temporal resolution) and functional magnetic resonance imaging (fMRI) (high spatial resolution), while human participants selectively attended to speakers in audiovisual scenes containing overlapping cocktail party speech. To utilise the advantages of the respective techniques, we analysed neural tracking of speech using the EEG data and performed representational dissimilarity-based EEG-fMRI fusion. We observed that attention enhanced neural tracking and modulated EEG correlates throughout the latencies studied. Further, attention-related enhancement of neural tracking fluctuated in predictable temporal profiles. We discuss how such temporal dynamics could arise from a combination of interactions between attention and prediction as well as plastic properties of the auditory cortex. EEG-fMRI fusion revealed attention-related iterative feedforward-feedback loops between hierarchically organised nodes of the ventral auditory object related processing stream. Our findings support models where attention facilitates dynamic neural changes in the auditory cortex, ultimately aiding discrimination of relevant sounds from irrelevant ones while conserving neural resources.

Effects of irrelevant unintelligible and intelligible background speech on spoken language production.

Earlier work has explored spoken word production during irrelevant background speech such as intelligible and unintelligible word lists. The present study compared how different types of irrelevant background speech (word lists vs. sentences) influenced spoken word production relative to a quiet control condition, and whether the influence depended on the intelligibility of the background speech. Experiment 1 presented native Dutch speakers with Chinese word lists and sentences. Experiment 2 presented a similar group with Dutch word lists and sentences. In both experiments, the lexical selection demands in speech production were manipulated by varying name agreement (high vs. low) of the to-be-named pictures. Results showed that background speech, regardless of its intelligibility, disrupted spoken word production relative to a quiet condition, but no effects of word lists versus sentences in either language were found. Moreover, the disruption by intelligible background speech compared with the quiet condition was eliminated when planning low name agreement pictures. These findings suggest that any speech, even unintelligible speech, interferes with production, which implies that the disruption of spoken word production is mainly phonological in nature. The disruption by intelligible background speech can be reduced or eliminated via top-down attentional engagement.

Staffs' physiological responses to irrelevant background speech and mental workload in open-plan bank office workspaces.

Acoustic comfort is one of the most critical challenges in the open-plan workspace. This study was aimed to assess the effect of irrelevant background speech (IBS) and mental workload (MWL) on staffs' physiological parameters in open-plan bank office workspaces. In this study, 109 male cashier staff of the banks were randomly selected. The 30-minute equivalent noise level (LAeq) of the participants was measured in three intervals at the beginning (section A), middle (section B), and end of working hours (section C). The heart rate (HR) and heart rate variability (HRV): low frequency (LF), high frequency (HF), and LF/HF of the staff were also recorded in sections A, B, and C. Moreover, staff was asked to rate the MWL using the NASA-Task load. The dominant frequency of the LAeq was 500 Hz, and the LAeq in the frequency range of 250 to 2000 was higher than other frequencies. The LAeq (500 Hz) was 55.82, 69.35, and 69.64 dB(A) in sections A, B, and C, respectively. The results show that the IBS affects staffs' physiological responses so that with increasing in IBS, the HF power decreases. Moreover, with higher MWL, increasing noise exposure, especially IBS, causes more increases in LF power and LF/HF ratio. It seems that the IBS can affect physiological responses and increase staff stress in open-plan bank office workspaces. Moreover, the mental workload can intensify these consequences in these working settings.

Loudness and Intelligibility of Irrelevant Background Speech Differentially Hinder Children's Short Story Reading

Reading skills are usually assessed in silent conditions, but children often experience noisy educational settings. Effects of auditory distraction on children's reading skills remain relatively unexplored. The present study investigates the influence of two features of background speech—intelligibility and loudness—on children's reading speed and comprehension. Sixty‐three 8‐to‐10‐year‐old elementary school children performed a reading task in the context of single‐talker background speech. Background speech was either intelligible or unintelligible and presented at low (45–50 dB SPL) or moderate (65–72 dB SPL) sound intensity (here termed “loudness”). Results showed a differential effect of intelligibility and loudness, respectively affecting children's comprehension and reading speed. In addition, the intelligibility effect was larger in children with lower interference control, as assessed with an auditory Stroop task. Our findings provide evidence for the influence of different properties of background speech on children's text reading with implications for reading in everyday classroom environments.Lay SummaryChildren often read in noisy environments, but we know little about how background chatter might affect their reading. Here, we found that 8–10‐year‐old children read stories more slowly with louder background speech. The children also understood less about a story if the background voice was speaking in their own language—especially those who, in a different task, were less able to ignore irrelevant but attention‐grabbing information. This suggests background speech differentially affects beginning readers.

The relation between the intelligibility of irrelevant speech and cognitive performance-A revised model based on laboratory studies.

Irrelevant background speech causes dissatisfaction and impairs cognitive performance in open-plan offices. The model of Hongisto (2005, Indoor Air, 15, 458-468) predicts the relation between cognitive performance and the intelligibility of speech described with an objectively measured quantity, the Speech Transmission Index (STI). The model has impacted research in psychology and room acoustics as well as the acoustic design guidelines of offices. However, the model was based on scarce empirical data. The aim of this study was to revise the model based on a systematic literature review, focusing on laboratory experiments manipulating the STI of speech by wide-band steady-state noise. Fourteen studies reporting altogether 34 tests of the STI-performance relation were included. According to Model 1 that includes all tests, performance begins to decrease approximately above STI=0.21 while the maximum decrease is reached at STI=0.44. Verbal short-term memory tasks were most strongly and very consistently affected by the STI of speech. The model for these tasks showed a deterioration in performance between STI 0.12 and 0.51. Some evidence of an STI-performance relation was found in verbal working memory tasks and limited evidence in complex verbal tasks. Further research is warranted, particularly concerning task-specific effects.

Auditory distraction in open-plan study environments: Effects of background speech and reverberation time on a collaboration task

Previous research has shown that semantic-based tasks are negatively influenced by semantic aspects in background speech. Collaboration is an important task in open-plan study environments and is a semantic task which might be disrupted by background speech. Therefore, the aim of this study was to analyze the influence of irrelevant background speech on student-collaboration.Participants worked in pairs to solve spot-the-difference puzzles, by using the 'DiapixUK' collaboration task, while they were exposed to different background sound scenarios. The composed sound scenarios varied in semantic content (mother tongue and foreign language background speech) and reverberation time (short vs long), the latter affecting speech intelligibility.Although a longer reverberation time decreases the intelligibility of background speech and a foreign language decreases meaningfulness of speech, no significant changes in performance were found. On the other hand, the data show an increased perceived disturbance for a longer reverberation time, which we interpret as an increased difficulty of interpersonal communication in the collaboration task due to the increased level of the background speech. The quiet reference condition was the most preferred sound condition which is in line with both the effect of a low background sound level and the absence of semantic interference.

Use of energy-equivalent sound pressure levels and percentile level differences to assess the impact of speech on cognitive performance and annoyance perception

Acoustical privacy is one of the most crucial, yet least satisfying aspects in open-plan offices. Irrelevant background speech impairs acoustic satisfaction and cognitive performance. Assessing acoustical conditions in occupied offices is challenging, and thus room acoustic parameters are commonly determined in unoccupied offices. In German speaking countries the rating level of noise is an important parameter occupational safety and health practitioners in the field often use to assess the acoustical conditions in occupied offices. The rating level denotes the energy-equivalent sound pressure level during a measurement period in an occupied office with speech sounds and takes penalties for tonal, informational and impulsive constituents into account. There is little evidence that the rating level correlates with the well-being, performance or health of office workers. As part of this study 89 different sound conditions under which subjects have to complete a number recall task and a questionnaire in laboratory conditions are evaluated with respect to their relationships with the rating level. In addition, these results are compared to percentile level statistics suggested as an alternative approach to assess the acoustical quality of office workplaces. Higher differences between the 10th and 90th percentile levels measured with fast time weighting lead to lower number recall performances and higher annoyance ratings whilst the rating level does not show any clear relationships.

Effects of the location of sound masking loudspeakers on cognitive performance in open-plan offices: Local sound masking is as efficient as conventional sound masking

Sound masking is a well-known measure to reduce the detrimental impact of irrelevant background speech in open-plan offices. However, the impact of the location of sound masking loudspeakers on the efficiency of masking systems with regard to cognitive performance has not yet been evaluated. This aspect is particularly important in decentralised sound masking architectures that enable individualised solutions but may depend highly on spatial release from masking. This paper reports on a study in an open-plan office with laboratory-like conditions. The subjects performed a serial recall task and completed a questionnaire during twelve different sound conditions with five different loudspeaker sets. With regard to serial recall performance, a disadvantage was observed when the speech and masker signals were presented from different horizontal directions of 90° as opposed to the same direction. Moreover, a similar disadvantage occurred when the masking sound was presented over six conventional sound masking loudspeakers that were mounted in the ceiling and positioned in a grid spacing of 2.4 m. However, when the cutoff frequency of the high-pass filter that was applied to the masker signal was lowered from 200 to 100 Hz, this disadvantage did not occur. Since the sound conditions with masking from the ceiling did not produce lower error rates and were not rated as less annoying, these results imply that a local sound masking system can improve the ability to concentrate at work as efficiently as a centralised approach.

Effects of irrelevant background speech on eye movements during reading.

The irrelevant speech effect (ISE) refers to the impairment of visual information processing by background speech. Prior research on the ISE has focused on short-term memory for visually presented word lists. The present research extends this work by using measurements of eye movements to examine effects of irrelevant background speech during Chinese reading. This enabled an examination of the ISE for a language in which access to semantic representations is not strongly mediated by phonology. Participants read sentences while exposed to meaningful irrelevant speech, meaningless speech (scrambled meaningful speech) or silence. A target word of high or low lexical frequency was embedded in each sentence. The results show that meaningful, but not meaningless, background speech produced increased re-reading. In addition, the appearance of a normal word frequency effect, characterised by longer fixation times on low- compared to high-frequency words, was delayed when meaningful or meaningless speech was present in the background. These findings show that irrelevant background speech can disrupt normal processes of reading comprehension and, in addition, that background noise can interfere with the early processing of words. The findings add to evidence showing that normal reading processes can be disrupted by environmental noise such as irrelevant background speech.

The effects of intelligible irrelevant background speech in offices – cognitive disturbance, annoyance, and solutions

Purpose – This paper aims to give an overview on four empirical studies which explored the impact of background speech on cognitive performance and subjectively perceived disturbance. Background speech is the most serious noise problem in shared-room and open-plan offices for employees who are supposed to do silent, concentrated work. Different measures of acoustic office optimization, as well as the outstanding role of the intelligibility of background speech for its disturbance impact, are empirically evaluated. Design/methodology/approach – The article provides a synopsis describing the core empirical results of four of our empirical studies. A survey study among office employees (n = 659) explored the subjective importance of office acoustics. Three experimental studies (n1 = 20; n2 = 30; n3 = 24) evaluated the effects of reduced background speech level, play-back of partial maskers and reduced speech intelligibility on cognitive performance and subjective ratings. Findings – Background speech is subjectively perceived as a severe problem, and the different noise abatement measures affect objective performance and subjective ratings differently. Speech intelligibility is – besides level – a key determinant for the acoustic optimization regarding these two dimensions. Research limitations/implications – Practitioners are encouraged to apply the findings and described measures when planning and/or evaluating open-plan offices. Practical implications – It is concluded that different acoustically efficient measures need to be combined to minimize the negative effects of background speech on cognitive performance and subjectively perceived disturbance. The aspired set value for open-office concepts is the lowest possible sound level with a bad intelligibility of the background speech at the same time. Originality/value – The synopsis of several empirical studies allows deriving comprehensive and well-founded information for practitioners involved in the evaluation and/or design of offices environments.

How Much Does Irrelevant Speech Impair Employees' Work Performance in Open-Plan Offices?

When people are talking in the background of an open-plan office it can be experienced as disturbing. However, it is not well specified how much irrelevant speech actually disrupts performance. The aims of the present study were, first, to investigate how much cognitive performance is impaired by irrelevant background speech with varying degrees of speech intelligibility, and second, to determine whether some office-related tasks are more susceptible than others. The results showed that cognitive performance decreased as a function of background speech intelligibility, the higher the intelligibility depicted by the Speech Transmission Index (STI), the worse the performance. The results indicated that the STI-value should be less than 0.50 (between the speaker and the listener), to avoid a negative influence on performance. Further, performance was more impaired by background speech if the focal task required episodic memory and rehearsal — such as word memory and information search. Interestingly, some tasks were insensitive for speech. This study also shows that the efforts to minimize speech intelligibility will yield increases in cognitive performance with a varying degree, depending on the type of focal task.

Cognitive performance during irrelevant speech: Effects of speech intelligibility and office-task characteristics

In open-plan offices, it is common that colleagues talk in the background while non-auditory tasks need to be performed. The aims of the present study were, first, to investigate how much cognitive performance is impaired by irrelevant background speech with varying degree of speech intelligibility, and second, to determine whether some office-related tasks are more susceptible to distraction than others. We tested a model developed by Hongisto [1] which predicts the decrease of cognitive performance as a function of speech intelligibility, depicted by the Speech Transmission Index (STI). Our results showed that the shape of the STI–performance curve, and the magnitude of the performance decrease, depend on task type. A semantic short-term memory task (i.e. word memory) was more sensitive to disruption by speech than a mathematical task. A word fluency task (i.e. retrieval of information from semantic long term memory) was not influenced by varying speech intelligibility. Moreover, performance on an Information search task was impaired by speech with high intelligibility only. The steepest slope in performance decrease appeared at a lower speech intelligibility value than predicted by Hongisto [1]. It also varied between cognitive tasks. The results of this study are useful in determining an appropriate target level for acoustic design in offices: This work demonstrates that attempts to minimize speech intelligibility will yield increases in cognitive performance with a varying degree, depending on the type of focal task.

Overlap of phonetic features as a determinant of the between-stream phonological similarity effect.

Serial recall from working memory is known to be impaired by the presence of irrelevant background speech, but several prior studies have concluded that the magnitude of the impairment is independent of the phonological relationship between to-be-remembered (TBR) and to-be-ignored (TBI) sources of information. In the present study, we examined the influence of between-stream phonological similarity in serial recall while attending to a heretofore uncontrolled variable, the phonetic feature. We found that TBI items sharing many phonetic features with TBR items produced significantly stronger working-memory impairments than TBI items with minimal phonetic feature overlap. In addition, participants were more likely to report remembering incorrect items that incorporated phonological characteristics of the TBI stream in the high-overlap condition. These findings provide evidence for subphonemic between-stream interactions and suggest that multiple parallel processes contribute to the irrelevant speech effect. We propose that a 2-component model, which combines the assumptions of process- and content-based accounts for the irrelevant speech effect, offers the best explanation for these findings.

Short article: Irrelevant speech effects and statistical learning

Immediate serial recall of visually presented verbal stimuli is impaired by the presence of irrelevant auditory background speech, the so-called irrelevant speech effect. Two of the three main accounts of this effect place restrictions on when it will be observed, limiting its occurrence either to items processed by the phonological loop (the phonological loop hypothesis) or to items that are not too dissimilar from the irrelevant speech (the feature model). A third, the object-oriented episodic record (O-OER) model, requires only that the memory task involves seriation. The present studies test these three accounts by examining whether irrelevant auditory speech will interfere with a task that does not involve the phonological loop, does not use stimuli that are compatible with those to be remembered, but does require seriation. Two experiments found that irrelevant speech led to lower levels of performance in a visual statistical learning task, offering more support for the O-OER model and posing a challenge for the other two accounts.

The Irrelevant Speech Effect and the Level of Interference in Aging

In general, no disproportionate detrimental effects of irrelevant background speech on cognition are found in aging individuals, although this is predicted by the inhibitory view of aging. This may be due to the nature of the primary task (most studies involve a verbal learning task) or the cognitive level at which irrelevant speech interferes with this task. In this study, the irrelevant speech effect on a numeric working memory task was investigated among 20 young (M = 21.8 years) and 20 older (M = 68.1 years) native Dutch individuals. Level of interference (LOI) was manipulated by presenting white noise (no interference), Russian words (low interference), Dutch words (phonological interference), and Dutch numbers (semantic interference) in the background. Results showed that reaction time increases as a function of LOI relative to silence, whereas accuracy remains unaffected. However, no interaction between LOI and age group was found, which suggests that the elderly were not disproportionately affected by an increased level of interference. These results are discussed in the light of the inhibitory view of aging.

Irrelevant speech effects and sequence learning

The irrelevant speech effect is the finding that performance on serial recall tasks is impaired by the presence of irrelevant background speech. According to the object-oriented episodic record (O-OER) model, this impairment is due to a conflict of order information from two different sources: the seriation of the irrelevant speech and the rehearsal of the order of the to-be-remembered items. We tested the model's prediction that irrelevant speech should impair performance on other tasks that involve seriation. Experiments 1 and 2 verified that both an irrelevant speech effect and a changing state effect would obtain in a between-subjects design in which a standard serial recall measure was used, allowing employment of a between-subjects design in subsequent experiments. Experiment 3 showed that performance on a sequence-learning task was impaired by the presence of irrelevant speech, and Experiment 4 verified that performance is worse when the irrelevant speech changes more (the changing state effect). These findings support the prediction made by the O-OER model that one essential component to the irrelevant speech effect is serial order information.

Insensitivity of visual short-term memory to irrelevant visual information.

Several authors have hypothesized that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996b). Experiment I replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery.

Testing Feature Interaction: Between-Stream Irrelevant Speech Effects in Immediate Recall

Immediate serial recall of visually presented lists is disrupted by irrelevant background speech. One explanation for the irrelevant speech effect assumes that features of the auditory material become incorporated into the memory trace of the to-be-remembered item thereby reducing the fidelity of the short-term trace. From this perspective the resultant short-term memory trace is a composite of features of the list item and features of an item in the irrelevant stream. While there is evidence that item interactions in short-term memory are observable, there is currently no direct empirical evidence for such interactions involving irrelevant speech. We report six experiments using a short-term cued recall task that manipulates proactive interference in which item interactions have been observed. In these experiments we consistently show that with irrelevant speech specific items in the auditory stream influence target recall and the presence or absence of proactive interference. These results provide relatively direct evidence for feature interaction involving irrelevant speech. The results are evaluated against the three current models of irrelevant speech effects.

On the irrelevance of phonological similarity to the irrelevant speech effect.

Irrelevant background speech disrupts immediate recall of visually presented items. Salamé and Baddeley (1982) found that increasing the phonological similarity between the irrelevant speech and the visual items greatly increased this disruption. In contrast, Jones and Macken (1995) found little evidence for such an increase. The present experiments directly manipulated the phonological similarity of the irrelevant speech background and the to-be-remembered visual items. Experiments 1-4 compared background speech that shared virtually no phonemes with the visual stimuli with background speech that shared all of the phonemes of the visual stimuli. No effect of phonological similarity was found. Experiment 5 replicated the method of Salamé and Baddeley's critical experiment but not their results. With regard to the two primary explanations of the irrelevant speech effect, these data present a strong challenge to the phonological store hypothesis while offering some support to the changing state hypothesis.