PROCEEDINGS of the
23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Background Noise and Phonological Processingin Second Language Learners
Emil HOLMER1; Thaisy COSTA; Mary RUDNER 2
Linnaeus Centre HEAD, Swedish Institute for Disability Research,
Department of Behavioural Sciences and Learning, Linköping University, Sweden

ABSTRACT
According to the Framework for Understanding Effortful Listening (FUEL), adverse listening conditions
deplete the cognitive resources available for other tasks. For example, in a noisy classroom, students may not
be able to devote their full cognitive capacity to learning. This may be a particular problem for second
language learners. In an experiment, 20 international exchange students and 9 Swedish students performed a
Swedish visual rhyme task in quiet and in noise. The rhyme task required the activation of phonologicalrepresentations of Swedish but on average the exchange students had been learning Swedish as a second
language in Sweden for only 3 months. T-testing showed that the exchange students had poorer Swedish
vocabulary and lexical access skills than the Swedish group but similar cognitive skills and a repeatedmeasures ANOVA based on rhyme task data showed a statistically significant effect of group with better
performance for the Swedish group. Unexpectedly, there was no effect of noise on visual Swedish rhyme
judgment and no significant interaction between noise condition and group. However, correlation patterns
suggested different language based strategies in quiet and in noise. This may suggest that phonologicalprocessing strategies are influenced by background noise which may have implications for listening effort.
Keywords: Framework for Understanding Effortful Listening (FUEL), Background noise, Phonologicalprocessing, Second language learner, Cognition

1. INTRODUCTION
In today’s global world, many students are acquiring knowledge through the medium of a languagethat is not their mother tongue. Thus, it is important to understand the effect of second language (L2)use on learning, and how this effect may interact with other known sources of classroom interference.
Background noise reduces the audibility of speech and contributes to listening effort. Both of theseeffects are greater for foreign speech, even when the listener is proficient in the L2 ( 1). Listening effort
can be understood in terms of the cognitive resources that are allocated to a listening task. The
Framework for Understanding Effortful Listening (FUEL, 2) describes the factors that contribute tolistening effort. These fall into two categories: individual factors and task demands. Listening effort
increases as task demands increase as long as the individual is motivated to continue listening and has
the necessary capacity to process the speech. However, if the listener is insufficiently motivated andthe task is hard, listening effort may drop as the individual opts out of the task. Thus, when there isbackground noise in a learning situation, more cognitive resources need to be devoted to simply
understanding what is being said, and learning suffers (3).
The Ease of Language Understanding Model (ELU, 4) describes the importance of phonologicalrepresentations in language understanding. According to the ELU model, speech understanding isachieved by matching the incoming speech stream to the phonological representations associated with
relevant lexical items stored in long-term memory. When background noise obscures parts of the
speech signal, or distracts attention from them, then a mismatch may occur. In this situation, thoseparts of the speech signal that have been perceived must be maintained in working memory until they
can be disambiguated using knowledge stored in long-term memory. Maintaining verbal information
in working memory is harder if the equivalent phonological representations are not already stored in
1
2

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emil.holmer@liu.semary.rudner@liu.selong-term memory (5). The process by which appropriate phonological representations beco me
established in long-term memory is described by the Developmental Ease of Language Understanding
Model (D-ELU, 6). The D-ELU proposes that deliberate processing of novel exemplars of lexical
items in working memory invokes updating of existing representations in long-term memory. If anovel exemplar significantly differs from pre-existing representations, a new phonological category isformed. Critically, exposure to and deliberate processing of linguistic input is the foundation ofdevelopment in native languages and L2s.
Background noise, not only makes it challenging to understand speech, it also hinders the functio nof verbal working memory (7). Thus, it is likely that background noise not only generates listening
effort by hindering speech perception but also by interfering with speech processing in working
memory. Verbal working memory processing is more fragile for L2 (8). Thus, it is likely that L2
phonological processing is more susceptible to noise. Speech-based phonological processing can be
disconnected from speech perception by using a visually based phonological processing task. The
purpose of the present study was to determine whether acoustic noise interferes with phonologicalprocessing in L2 learners.
We have previously developed the Cross-modal Phonological Awareness Test (C-PhAT, 11). The
test is designated cross-modal because it is designed to test phonological awareness in speakers of
Swedish and users of Swedish Sign Language (SSL), using the same set of materials. The materials arepairs of characters with phonological labels in both Swedish and SSL. However, the mapping between
the written characters and phonology differs for the two languages. In the present study, we exploit thedifference in mapping between written characters and phonology between different languages to test
the efficiency of phonological processing in learners of Swedish as L2. In this context, the mapping
between the characters and phonology in accordance with the Swedish manual systems is immaterial.
Successful performance on the C-PhAT requires not only the ability to map written characters tophonology, but also the ability to maintain the resulting phonological representations in working
memory until it has been determined whether or not those representations are phonologically similar.
Our prediction is that not only will mapping between written characters and Swedish phonology be
fragile in Swedish L2 speakers but also that the resulting Swedish phonological representations will beless robust and thus less durable in working memory than the representations of native speakers. This
is in some sense similar to the fading of phonological representations in adults with post -lingual
hearing loss (12). Importantly, for the purposes of this study, phonological representations are likely tobe susceptible to noise, and the more fragile they are, the more susceptible to noise they are likely tobe.
The FUEL (2) highlights the multiple causes of listening effort. Some of these are bottom-up signal
related phenomena such as noise and others are top-down phenomena related to the individual such as
motivation and knowledge, including language knowledge. If acoustic noise interferes with thephonological processing required to perform successfully on a visual rhyme task in L2 learners, then it
is also likely to interfere with their ability to process spoken Swedish in a learning situation.

2. METHODS
2.1 Participants
Twenty foreign exchange students at Linköping University (6 males, mean age 24 years) took partin the study along with a comparison group of nine students at Linköping University (3 males, mean
age 24 years) who were native Swedish speakers. The foreign exchange students included ten
Europeans, five South Americans, four Asians and one African; all of them were studying Swedish asa second language and had been in Sweden for on average 3 months, ranging between two and six
months. All participants gave written informed consent.
2.2 Experimental task
The Cross-modal Phonological Awareness Test (C-PhAT, 11) is a visual rhyme task that taps into
phonological processing. Pairs of characters, either two letters or one letter and one digit, arepresented on a computer screen and the participant makes a decision on the phonologicalcharacteristics of those characters as quickly as possible. There are two versions of C-PhAT, a Swedish
version and a Swedish Sign Language version. The two versions are based on identical materials; only
the instructions given to the participant differ. The Swedish version was used in the present study. In
this version, the participants are asked to determine whether the Swedish labels of the two characters5961

rhyme with each other. For example, the Swedish labels of “U” (/ʉː/) and “7” (/ɧʉː/) but not “E” (/eː/)and “H” (/hoː/) rhyme with each other. “Yes” and “No” button-press responses are collected
automatically and d’ is calculated by adjusting hits for false alarms to adjust for response bias inaccordance with signal-detection theory. The dependent variables from the experiment are d’ andresponse time (RT) for correct responses.
There are two sets of C-PhAT material each including 24 trials and in the present study allparticipants performed the task with both sets of material in balanced order. One set of visual materials
was presented in quiet and the other in background noise consisting of the International Speech Test
Signal Noise (13). The materials were presented in black capital letters (Times New Roman, 115
points), on a white background using a laptop computer (Dell notebook, 2012). The noise waspresented using the soundcard of the laptop computer at the same comfortable level (18%) for allparticipants over headphones, and headphones were worn for the duration of the experimental task toensure that any effect of noise was not confounded by the effect of wearing headphones. Thus, mean d’and RT were calculated for quiet and noise conditions.
2.3 Behavioural test battery
Apart from the experimental task, six other behavioural tests were administered to all participants.
These were Ravens Advanced matrices (9) which is a test of non-verbal cognition, a Swedish
vocabulary test (10) and four tests reported in (11):Motor speed. The participant pressed one key as fast as possible 30 times using the dominant hand.
The dependent measure was mean response time in s for one keypress.
Cognitive speed. The Swedish words for ‘‘yes’’ and ‘‘no’’ were presented in unpredictable order on
a computer screen for a maximum of five s and the participant’s task was to press the corresponding
key as fast as possible. The dependent variable was the mean response time for correct trials.
Letter decision. In the letter decision task letters were presented on a computer screen either in thecorrect orientation, or rotated 45, 90 or 180 degrees in the plane of the screen. The participant’s task
was to determine whether each item was correctly oriented or not during the five second presentation
period and make the appropriate keypress response as fast as possible. The dependent variable waspercent correct responses.
Lexical decision. Items consisting of three letters (two consonants and one vowel) were presented
on a computer screen for a maximum of five s and the participant’s task was to determine whether each
item was a Swedish word or not and give a key-press response as quickly as possible. There were 40
trials and half the items were targets. The other 20 items were equal numbers of pseudowords(orthographically legal but non-lexicalized items) and non-words (orthographically illegal items). The
dependent measures was d’.
2.4 Data analysis
The data (d’ and RT) from the experimental task were analysed using repeated measures analysis ofvariance (ANOVA) for the foreign exchange students alone and then for both groups together. T-tests
were performed to determine between-group differences in test battery performance. Pearson’s
correlations between the experimental task and test battery performance were also calculated for all 29
participants.

3. RESULTS
3.1 Experiment
Experimental data were normally distributed and performance is shown in Figure 1. Two repeatedmeasures ANOVAs were performed with d’ as the dependent variable, first one for the L2 group alone
and another across groups. Both ANOVAs included noise as a within-group factor. Neither of the
ANOVAs showed a main effect of noise, L2: F (1, 19) = 0.04, MSE = 0.03, p = .85; across-group: F (1, 27)= .97, MSE = 1.07, p = .35. The effect of group was significant, F (1, 27) = 12.18, MSE = 0.94, p = . 001,
but there was no significant interaction between group and noise, F(1, 27) = 1.28, MSE = 1.07, p = .27.
Due to the lack of the expected effect of noise, we performed the same set of ANOVAs with RT as thedependent variable. However, there was no significant effect of noise in either of the RT ANOVAs, L2:
F (1, 19) = .59, p = .45; across-group: F (1, 27) = .004, p = .95. The effect of group was small and did notreach significance, F (1, 27) = 4.02, p = . 055, η2 = .13 and there was no significant interaction between
group and noise, F (1, 27) = .55, p = .55.

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Figure 1. C-PhAT performance. Error bars show standard error.
3.2 Behavioural test battery
Non-normal distributions were detected for Button pressing, Physical matching, Lexical decision,
Letter identification, and Vocabulary but not Ravens matrices. The results of the test battery are shownin Table 1. Importantly, the two groups did not differ on Ravens Advanced Matrices, the measure ofnon-verbal cognition. Three of the L2 participants did not complete this test due to fatigue.
Unexpectedly, the L2 group showed slower motor speed. However, there was no difference between
groups on Physical Matching, our measure of cognitive speed. As expected, the L2 group had poorer
Swedish vocabulary and poorer Swedish lexical decision ability. Two of the L2 participants did notcomplete the vocabulary test due to fatigue. It should also be noted that the L2 group had poorer letter
identification than the Swedish comparison group. This may have been due to varying degree offamiliarity with the Latin alphabet in the L2 group.
Table 1. Performance in the behavioural test battery for the L2 group (n=20) and the Swedishcomparison group (n=9). Missing data from L2 participants in Ravens Advanced Matrices (n=17) andVocabulary (n=18).

Button pressing
Physical Matching, d'
Lexical decision, d'Letter identification, d'
Vocabulary
Ravens Advanced Matrices

SwedishL2
Mean SD Mean SD
76.21 24.89 130.52 94.18
2.61 0.31
2.72 0.51
3.22 0.68
1.00 0.41
3.60 0.17
3.37 0.31
71.67 0.50 53.94 7.92
12.78 3.96 14.00 3.12

t-testp
sign.
0.03 *
0.47< .001 ***0.02 *< .001 ***0.44

3.3 Correlations
We report results from parametric tests, with a comment when non -parametric test showed adifferent result. C-PhAT performance correlated significantly with lexical decision, N = 29, r = .50, p= .006, and vocabulary, N = 27, r = .44, p = .02, but only in the quiet condition. There was also asignificant correlation between lexical decision and vocabulary, N = 27, r = .72, p < .001. The pattern
was the same for non-parametric correlations, except for the association between C-PhAT performancein the quite condition and Button pressing which was significant for the non-parametric test, N = 29, rs= -.44, p = .017. There were no other significant correlations between C-PhAT and the behavioural test
battery. Surprisingly, there was no significant correlation between C-PhAT performance under the two
conditions (quiet and noise).

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4. DISCUSSION
The purpose of the present study was to determine whether acoustic background noise interfereswith phonological processing in L2 learners. To this end, 20 adult exchange stude nts who had been in
Sweden between two and six months and who were learning Swedish performed a visual rhyme task
(C-PhAT, 11) in quiet and in noise. ANOVA provided no evidence of an effect of acoustic noise on
visual rhyme judgment in the L2 group. Thus, we found no evidence to support the notion thatbackground noise contributes to effort in L2 listeners by interfering with phonological processing.
There was no floor effect at group level that could have been driving the lack of an effect of noise. The
noise used in the present study was ISTS noise that is created from short segments of speech in six
different languages (13) and is thus speech-like but unintelligible. Previous work has shown thatcompeting speech interferes more with both recognition and cognitive processing of speech than otherkinds of fluctuating noise (14). Thus, there is no reason to suppose that our results are unreliable dueto the sensitivity of the test or the type of noise used. However, although the same comfortable noiselevel was used for all participants, the absolute level of the noise was not measured in the present study.
It is possible that the noise level was too low to interfere with phonological processing. In future work,
the noise level should be well controlled.
Although there was no effect of noise on C-PhAT performance, there was no correlation between
the two conditions and further, the pattern of associations between C -PhAT performance and the
behavioural test battery differed between conditions. This suggests that C-PhAT scores weredifferently distributed in quiet and noise conditions. Specifically, vocabulary and lexical decisionperformance predicted C-PhAT performance in quiet but not in noise. Non-parametric tests suggested
a similar predictive value for Button Pressing. This suggests that the size of the Swedish lexicon andefficiency in searching it, as well as motor speed, were important for making phonological decisions inquiet but not in noise. According to the ELU model (4), access to the mental lexicon and thephonological representations stored there is vital for language understanding and that it is this processthat is disturbed under challenging listening conditions when background noise is present. The patternof correlations in the present study support this notion.
As predicted, there was a significant difference between the two groups in rhyme judgment
performance demonstrating poorer ability in the L2 group to process Swedish phonology. The L2
group also had poorer vocabulary and slower lexical access than the Swedish group. Although wecannot separate the effects of phonological representation and processing, i t is likely that thediscrepancy is due to poorer phonological representations in the L2 group due to their short exposureof on average 3 months to Swedish. Because there was no difference between group s in non-verbal
cognition, it is unlikely that the effect of group is due to differences in the ability to processrepresentations.

5. CONCLUSIONSThe FUEL (2) highlights multiple causes of listening effort, some of which are related to perception
and some to cognition and yet others to individual factors such as motivation. We found no significant
effect of background noise on L2 phonological processing in young adults and thus no hard evidence
that background noise specifically causes listening effort at the cognitive level in early L2 learners.
However, differences in correlation patterns suggested different phonological processing strategies inquiet and in noise, in line with the ELU model (4) and this in turn suggests a redistribution of cognitive
resources. This phenomenon deserves further investigation.

ACKNOWLEDGEMENTS
This work was supported by the Swedish Research Council Grant 2017-06092 and through fundingof the Linnaeus Centre HEAD Grant 349-2007-8654.

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