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Original Article
ARTICLE IN PRESS
doi:
10.25259/JHS-2024-10-16-R1-(1620)

Binaural Processing and Auditory Working Memory in Individuals With Stuttering

, ,
1Department of Audiology, All India Institute of Speech and Hearing, Mysore, India
2Department of Speech, Language and Hearing Sciences, University of Texas at Austin, United States

* Corresponding author: Sanjay Shankar, Department of Audiology, All India Institute of Speech and Hearing, Mysore, India. ssanjay2511998@gmail.com

Received: , Accepted: ,
© 2025 Published by Scientific Scholar on behalf of Journal of Health and Allied Sciences NU
Licence
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Shankar S, Aryal S, Prabhu P. Binaural Processing and Auditory Working Memory in Individuals With Stuttering. J Health Allied Sci NU. doi: 10.25259/JHS-2024-10-16-R1-(1620)

Abstract

Objectives

Stuttering may result in deficits in working memory and auditory processing at various levels of the auditory pathway because of the interruptions brought on by the disfluencies. Therefore, our study aimed to assess persons who stutter working memory and binaural processing.

Material and Methods

The binaural interaction was assessed using tests for interaural time differences and interaural level differences. The dichotic consonant-vowel test was used to evaluate the binaural integration process. Working memory was assessed using the audio 2N-Back span and audio descending span tests. A t-test was applied to determine the statistical significance of the group variation.

Results

According to an independent t-test, the stuttering group’s interaural level and time difference scores were considerably lower. Additionally, individuals with stuttering performed worse on auditory working memory tasks and the dichotic consonant-vowel test. Hence, the study concludes that an individual who stutters may have a brainstem and cortical auditory processing deficit.

Conclusion

The binaural processing test results show that individuals with stuttering have abnormalities in cortical and brainstem auditory processing. This processing deficiency may impact the ability to perceive speech. Our study’s findings encourage clinicians to develop test protocols that include working memory and binaural processing tests for individuals with stuttering.

Keywords

CAPD
Interaction
Integration
Stuttering
Working memory

INTRODUCTION

Stuttering is defined as a disorder that is characterised by involuntary disruption in fluency. An abnormal frequency or duration of interruptions in the flow of speech, including repetitions, prolongations, and blocks, distinguishes this disorder.[1] Stuttering has a prevalence rate of around 0.7 to 1%.[2] Even though several aetiologies have been presented to explain it, the reason for stuttering remains unclear.[1] Various models have been developed to explain stuttering, including abnormal neurophysiology, genetic variables, a person’s environment, personality, learning aptitude, auditory processing, language processing, and the association between speech and stuttering.[1] Multiple studies have demonstrated structural and functional differences in the brains of people who stutter and those who do not. Anatomical differences include adults with stutters showing larger planum temporal areas on the brain’s right and left sides.[3] However, the findings were not replicated in the study done by Watkins et al.[4] Similarly, the study by Choo et al.[5] states that fundamental differences may occur regarding processing abilities and can also be related to the central auditory processing deficit.

Auditory processing refers to the brain’s ability to interpret and make sense of sounds received by the ears. This involves several key functions, including sound detection, localisation, and the processing of speech and environmental sounds. The brain differentiates between pitches, localises sound sources, and comprehends speech, particularly in noisy environments. Auditory processing also includes auditory attention, memory, and discrimination, which are essential for communication and learning. When individuals experience difficulty in these areas despite normal hearing, it can lead to central auditory processing disorder (CAPD). CAPD is characterised by listening difficulties caused by defective bottom-up processing of sounds by the brain, according to the Speech-Language and Hearing Association.[6] It is also characterised by a poor perception of sounds, including speech and non-speech, not caused by peripheral or intellectual hearing loss.

The CAPD test battery consists of verbal and non-verbal tests, including standard audiometric tests, psychological tests, speech audiometric tests in noise and quiet, competing speech tests, dichotic listening tests, and temporal processing tests.[6] Despite the various assessments used over the last 60 years, CAPD and its impact on other related disorders are poorly understood. The literature has widely explored the association between stuttering and CAPD.[7,8] Consequently, many studies have continued to investigate this disorder, and researchers hypothesise that there is a disruption in the auditory feedback loop in individuals with stuttering.[9,10] This means that because these individuals do not get appropriate auditory feedback, they develop a misperception that an error in speech has happened, and the condition is known as stuttering. These studies have demonstrated that there is indeed a link between the auditory system and stuttering.

Stuttering is a prevalent speech issue that is dynamic and complex. Literature has shown that there can be a deficit in auditory processing in individuals with stuttering where reduced temporal processing deficit,[10,11] binaural processing,[12] supra-segmental and decoding deficits[9] have been reported. In their review, Farazi et al.,[8] concluded that the auditory temporal processing deficit is one of the causes of stuttering, which disturbs the auditory feedback to the brain’s speech control, resulting in instability in the neural representation of speech sounds. Similarly, the study by Andrade et al.[9] reported the presence of auditory decoding and temporal coding deficits among individuals with stuttering.

The deficit in auditory processing can be assessed using behavioural and electrophysiological measures. In the literature, using both electrophysiological and behavioural measures, it is found that the auditory brainstem is the possible source of central auditory deficiency, which affects the binaural interaction process among individuals with stuttering.[7,13] Kramer et al.[14] reported poorer masking level difference (MLD), suggesting impaired brainstem auditory processing among persons who stutter. Interaural time difference (ITD) and interaural level difference (ILD) are the two cues required for directional hearing across the frequencies (i.e., ITD for low frequencies and ILD for higher frequencies).[14] They are considered significant cues for binaural interaction.[15] The lateral superior olive (LSO) processes ILDs of high-frequency sounds. In contrast, the ITDs of low-frequency sounds are processed in both the lateral and medial superior olive nuclei (MSO).[16] For individuals who stutter, difficulties in binaural processing could potentially affect their ability to perceive and respond to auditory cues, such as distinguishing speech from background noise or localising sound sources. However, in the literature, binaural processing ability has not been assessed using ILD and ITD tests among individuals with stuttering.

Binaural integration can be assessed using behavioural tests such as dichotic consonant-vowel (CV), dichotic rhymes, and dichotic digits. Dichotic CV is the most widely used behavioural test for assessing cortical functioning and hemispheric lateralisation. Robb et al.[17] reported no significant difference in the dichotic CV score among adults with stutterers and non-stutterers in the directed attention task.[17] It is unclear how the auditory system relates to stuttering and which part of the auditory processing problem produces stuttering. By evaluating dichotic listening performance, researchers can gain insights into whether stuttering is associated with altered auditory attention or hemispheric imbalances, both of which might impact speech processing and contribute to stuttering symptoms. The study aims to clarify further the role of auditory processing dysfunction in the adult population with stuttering.

The literature investigated the connection between stuttering and cognition. Bosshardt[18] states that attention-demanding cognitive processes can interfere with persons who stutter speech. Functional magnetic resonance imaging (fMRI) showed overlapping neural system activation during sentence generation and production to a greater extent in the stutterer.[18] Auditory working memory is responsible for taking in the information presented orally, processing it, storing it in one’s mind, and recalling what has been heard, which is associated with task-dependent manipulations. This is the fundamental function of our brain and is involved in many higher cognitive tasks. Working memory is the neurocognitive system that temporarily stores and processes incoming information.[19] Central executive and phonological memory deficits are implicated in various communication disorders.[20] Given the brain’s limited resources, working memory relies on the efficient use of available neural capacity. In individuals who stutter, it is suggested that the neural resources required for speech production may compete with those needed for working memory tasks,[21] potentially leading to a reduction in the capacity available for processing and retaining information. This theory posits that the cognitive load associated with stuttering may interfere with working memory, ultimately affecting the individual’s ability to store, manipulate, and retrieve information effectively. Hence, the study’s rationale is to explore how auditory working memory is affected in individuals with stuttering.

Our study’s primary goal is to investigate how people who stutter process and integrate sounds, particularly binaural interaction and integration. The study also intends to examine persons who stutter auditory working memory capabilities. The deficit in attention-based auditory working memory will directly alter the findings of binaural auditory processing, as attention and memory are critical factors for completing the task of binaural processing. The problem in the higher-order neurocognitive processing would alter the auditory processing findings. Hence, this study attempts to understand binaural processing and auditory working memory abilities in adults with stuttering.

MATERIAL AND METHODS

Participants

The study involved two groups: an experimental group of individuals who stutter and a control group of healthy participants who had not reported any other concerns, such as language, hearing, cognitive functioning, or other issues. Participants >40 years of age were excluded to reduce the impact of aging on the findings of the auditory processing test. To minimise the effect of task complexity on test outcomes, individuals with illiteracy or education levels below the equivalent of a school education were excluded from the study.

We enrolled twenty adult stuttering individuals in the experimental group. Nineteen (95%) of the twenty individuals in the stuttering group were male, and one (5%) was female. The participants’ average age was 21.8 years (SD = 5.32 years). Twenty healthy participants (mean age = 20, SD = 5.7) without stuttering, hearing loss, or ear/health issues made up the control group (non-stuttering). In both the stuttering and control groups, the gender ratio was kept the same.

The G*power analysis[22] was utilised to determine the sample. According to power analysis, 42 samples were needed for an effect size of 0.8 and a power of 0.80 at a significance level (p) of 0.05. This led to the conclusion that the study sample of 40 (20 stuttering and 20 non-stuttering) was suitable. The testing process included working memory tasks outlined below, audiological evaluation, and stuttering assessment using the stuttering severity instrument (SSI-4), as well as central auditory test batteries.

Materials

Ethical approval for the study was obtained from the institutional review board (IRB) of the Institute, under approval number SH/ERB/2022-23/47. The participants underwent a series of evaluations, starting with an audiological examination that included an otoscopy to confirm the absence of middle ear or external ear issues, tympanometry to assess middle ear function, and pure-tone audiometry to measure air and bone conduction thresholds. The audiometric testing followed American National Standards Institute standards and normal hearing was defined as an average air conduction threshold of 15 dB HL or less. In addition to the audiological assessments, the participants’ stuttering severity was measured using the SSI-4, which involved evaluating speech in both structured and unstructured settings, such as natural conversation and reading a passage. The psychoacoustic tests to assess auditory processing included the dichotic CV test, as well as tests of ILD and ITD, conducted using MATLAB R2014.0a software and the Psychoacoustic Toolbox. The test stimuli were noise-based, and the 3AFC (three-alternate forced choice) staircase method was employed. Additionally, working memory was assessed using the Smrithi Shravan software, developed at the All India Institute of Speech and Hearing, Mysore, India. This software is a customised platform to assess auditory and visual memory. The cognitive tests included forward digit span, backward digit span, running span, N-back, and operation span tests, which assessed auditory attention, sequencing, and working memory. Which included the 2N-back test and the Descending Span Audio test, both administered with 40 dB SL calibrated headphones.

Procedure

Audiological evaluation

Through otoscopic examination, it was confirmed that there were no active middle ear or external ear illnesses in the participants’ ears before their inclusion in the study. Additionally, the audiological evaluation process includes tympanometry and pure tone audiometry. In the sound-treated room, the hearing threshold was measured from 250 Hz and 8 kHz (air conduction) and between 250 Hz and 4 kHz (bone conduction). The sound-treated room followed ANSI norms. The standard for normal hearing was defined as an average air conduction value of 15 dB HL or less. The middle ear/external ear status was assessed using tympanometry. The probe tone utilized was 226 Hz. The typical requirements were the middle ear pressure range of +60 to -100 daPa and compliance from 0.5 to 1.75 mL.[23]

Stuttering severity instrument (SSI-4)

The stuttering severity was assessed using the English version of the SSI-4.[24] The responses of their speech sample in both structured and unstructured settings (i.e., natural conversation and reading passage) were used to calculate the total score and determine the severity of the stuttering. A score of 10–17 is indicative of very mild stuttering, 18–24 of mild stuttering, 25–31 of moderate stuttering, 32–36 of severe stuttering, and 37–46 of severe stuttering.

Auditory processing evaluation

Tests measuring binaural interaction and integration were used to assess binaural processing. The dichotic CV test was used to evaluate the binaural integration process, while the ITD and ILD tests were utilised to examine the binaural interaction process. Before administering each test to every participant, the participants were briefed about its complexity and made comfortable with its material and procedure.

The psychoacoustic toolbox and MATLAB R2014.0a software[25] were utilised to test ILD and ITD. The stimulus was noise discrimination. The three down, one up staircase option was used with the three 3AFC. Considering a standard level of -30, the employed starting level was 3. A factor of two was employed with five reversals. The threshold’s reversal was established at two.

Using a 0 ms lag time, the dichotic CV test[26] was used to evaluate the binaural integration process. Standardised dichotic CV material was developed for the Indian population, and a laptop and high-quality circumaural HDA 200 headphones with stereo presentation characteristics were used to conduct the test in a soundproof environment. The 30 bisyllabic stimuli that comprise the dichotic CV material were delivered simultaneously to both ears but were distinct in each case. For each participant, the following scores were computed: double correct score (DCS), right ear single correct score (SCS), left ear SCS, and right ear advantage (REA). The order of testing was counterbalanced across the participants, and to prevent fatigue or cognitive overload, adequate breaks were provided to participants as needed.

Working memory evaluation

Working memory was evaluated using the Smrithi Shravan software. The 2N-back test and the descending span audio test were administered to each participant to assess working memory. In the 2N-back test, participants repeat the second-last stimulus after hearing each stimulus only in auditory mode. In the same way, participants in the descending audio span test are required to listen to every stimulus presented in auditory mode and arrange them in descending order. A practice stimulus was provided before the testing stimuli to help familiarise with the test. The subject’s task was to rearrange the numbers displayed in descending sequence by employing the 40 dB SL calibrated headphones in auditory mode. The top four reversals out of six were averaged to determine the midpoint of the responses. This was done in case the last trials were impacted by exhaustion, and the early trials could be impacted since it would take the subject some time to become accustomed to the task (even though they had two practice trials before the test started). Therefore, the average of the four best trials was used to determine the score for each cognitive test.

The 2N-Back test used the following testing parameters: 20 trials with a response time of 5000 ms; an auditory stimulus period of 3000 ms for each digit of five to seven numbers; an inter-stimulus interval of 1000 ms; and three numbers of reversal. For every participant, the maximum number of stimuli accurately memorised was computed. If the respondent could recall where item two was located after two turns back, the response received a score of 1.

Statistical analysis

The data analysis was done using statistical software for social sciences (SPSS; IBM Corp., Ver. 25.0). There were no outliers, and the distribution was normal, according to the Shapiro-Wilk’s normality test (p >0.05 for all the test scores). A parametric independent t-test was employed to ascertain the significant differences between the stuttering and control groups. The test score was the dependent variable, and the stuttering was the independent variable. The p-value of 0.05 or less was utilised as the threshold for statistical significance at a 95% confidence interval. A test score comparison has been made between two groups, i.e., stuttering and the control groups.

RESULTS

Audiological evaluation

During the otoscopic examination, every study participant had a normal appearance of the middle and external ears. The average air conduction threshold for the stuttering group was 6.86 dB HL (SD=4.38) for the right ear and 6.08 dB HL (SD=4.92) for the left ear across all participants. Comparably, for the control group, the right ear measured 7.84 dB HL (SD= 3.99), and the left ear measured 6.57 dB HL (SD= 3.2). The air conduction threshold did not show a statistically significant difference between the study and control group (p>0.05). The tympanometry results of the stuttering and control groups revealed the presence of an “A” type tympanogram in both ears for most of the participants. As three participants who had ‘As’ tympanogram with low static admittance did not have any symptoms of external and middle ear pathologies with a normal audiogram, all 40 participants were included in the study.

Stuttering characteristics

SSI-4 was administered in both the stuttering and control groups. Based on the SSI-4, among 20 participants of the experimental group, 7 (35%) had mild stuttering, 5(25%) had moderate stuttering, and 8(40%) had severe stuttering, which was based on SSI-4. Similarly, 20 participants in the control group did not show any stuttering features, with a score of 0.

Binaural Interaction in stuttering and control group

We evaluated the results of the ITD and ILD. The stuttering and control groups were compared to examine the capacities for binaural interaction. Table 1 shows that the stuttering group’s mean ITD and ILD values were more significant than the control groups. The results of the independent t-test revealed a significant difference between the two groups: ITD (t(38)= 2.97, p= 0.001) and ILD (t(38)= -5.28, p< 0.001). Table 1 displays the outcomes of the ITD and ILD tests for the stuttering and control groups.

Table 1: Comparison of interaural time difference and interaural level difference between stuttering and control group on Independent t-test
Test measure Control group
 Stuttering group
 Test result (t-value) df p-value
Mean SD Mean SD
ILD 4.19 1.34 3.18 0.86 -5.28 38 < 0.001
ITD 1.04 1.15 2.85 0.97 2.97 38 <0.001

SD: Standard deviation, df: Degree of freedom, ILD: Interaural level difference, ITD: Interaural time difference.

Binaural integration in stuttering and control group

The dichotic CV test result was examined to determine the integration skills of the control and stuttering groups. Compared to the control group, the stuttering group had lower mean values for the left ear SCS, right ear SCS, and DCS.

A statistical analysis using an independent t-test revealed a significant difference between the two groups’ mean scores for the right ear SCS (t (38) = 7.08, p<0.001, left ear SCS (t (38) = 5.09, p<0.001, and DCS (t (38) = 7.73, p<0.001). The control group’s mean score was significantly better than the stuttering group’s. Table 2 provides a detailed illustration of the independent t-test result.

Table 2: Result of comparison of dichotic CV test score between stuttering and control group in independent t-test
DCV measure Stuttering group
 Control group
 Test results (t-value) df p-value
Mean SD Mean SD
Right ear SCS 18.15 1.72 24.55 3.71 7.08 38 < 0.001
Left ear SCS 17.95 1.71 23 4.07 5.09 38 < 0.001
DCS 11.05 1.56 19.3 4.46 7.73 38 < 0.001

DCV: Dichotic consonant-vowel, SCS: Single correct score, DCS: Double correct score, SD: Standard deviation, df: Degree of freedom.

Right ear advantage

When the mean scores for the right and left ears were compared between the stuttering and the control groups, it was apparent that the stuttering group had a REA. However, an independent t-test with t (38) = 1.66, p = 0.11 revealed no statistically significant difference between the stuttering and comparison groups. Table 3 shows the specific outcome of the REA.

Table 3: Result of right ear advantage, descending span audio test and 2N-Back test for stuttering group and control group (N=40) in independent t-test
Test measure Stuttering group (N=20)
 Control group (N=20)
 Test result (t-value) df p-value
Mean SD Mean SD
Right ear advantage 0.15 1.25 1.55 3.71 1.66 38 0.11
Descending span audio test (Mid-point score) 4.63 1.14 6.71 1.56 4.69 38 < 0.001
Descending span audio test (Maximum score) 6.28 1.18 8.25 1.65 4.19 38 <0.001
2N-Back test 15.29 1.41 19.45 0.83 11.69 38 <0.001

SD: Standard deviation, df: Degree of freedom.

Working memory in stuttering and control group

The results of the 2N-Back and descending audio span tests were evaluated to compare the stuttering group’s working memory capacity with that of the control group. In every working memory test, the mean score of the stuttering group respondents was lower than that of the control group.

The results of the independent t-test revealed that the stuttering group had a lower working memory capacity on the descending audio span test, with a median score of t (38) = 4.69, p< 0.001, and a maximum score of t (38) = 4.19, p= 0.001. The 2N-Back audio span test also revealed a statistically significant difference (t (38) = 11.69, p<0.001) between the two groups. Table 3 shows the outcome of the independent t-test on the working memory tests.

DISCUSSION

Our study aimed to compare binaural auditory processing abilities and auditory working memory among adult individuals with and without stuttering. Binaural interaction abilities were assessed using ITD and ILD tasks, binaural integration abilities were evaluated using a dichotic listening task, and working memory abilities were assessed using a descending audio span and 2N-back test.

Binaural interaction and stuttering

The results of the ITD and ILD show poor performance in binaural interaction abilities among individuals with stuttering. These results suggest poorer scores in auditory processing ability tests among adults with stuttering than those without. These results suggest difficulties in localising sound sources and perceptual segregation of sound sources among individuals with stuttering. The study by[27] reported inconsistent responses in the localisation task when children were asked to localise the sound presented through an audiometer.[28] The findings of our reported poorer localisation ability among individuals with stuttering. However, this is the first study of this kind to evaluate the processing of brainstem structures through these behavioural tests in an adult population, and results need to be replicated in the future.

The binaural interaction component of auditory brainstem response administered across the literature has shown that individuals with stuttering have deficit binaural interaction, projecting brainstem structures as the possible site of central auditory deficiency.[7] Our study using behavioural tests supports the findings of electrophysiological tests. It suggests the need for detailed audiological assessment using different audiological measures among individuals with stuttering.

Binaural integration and stuttering

Binaural integration abilities were assessed using a dichotic listening test among individuals with stuttering. Our study showed poorer performance in dichotic listening in persons who stutter, indicating a deficit in the cortical processing among individuals with stuttering.

Neuroimaging studies have shown the presence of various structural abnormalities in the cortical structures, including the absence of activation of the left inferior frontal and primary auditory cortices (i.e., areas associated with self-monitoring, comprehension, and fluency) among individuals with stuttering.[29] Similarly, researchers reported the presence of a larger corpus callosum among adults with stuttering.[5] The adults who stutter had higher grey matter volume in the speech-related areas, such as the inferior frontal gyrus, insula, and superior temporal gyrus.[30] Likewise, in the children who stutter, Beal et al.[30] found less white matter volume in the forceps minor of the corpus callosum. Hence, the poorer scores on the SCS and DCS for dichotic listening among individuals with stuttering support the findings of the neuroimaging studies.

Although REA is present in children, the corpus callosum will fully develop by age 12, and the REA disappears in adolescence.[31] The two models that explain the REA are the structural and attention models. The structural model describes the role of the corpus callosum for REA and is also known as the bottom-up processing model. However, the second model explains the role of directed attention to the right or left ear for the REA.[31] Our study did not show significant differences in the REA value between the stuttering and control groups. This suggests that, for auditory processing tasks, stuttering may not necessarily result in a lateralised advantage or deficit in the right ear, indicating that auditory processing in stuttering individuals may be more bilaterally distributed. The research results support the findings of Robb et al.[17] who reported no differences in the REA among individuals with stuttering. These results suggest similar cerebral lateralisation as a control group for auditory processing among adult individuals with stuttering.

Auditory working memory and stuttering

Auditory working memory was assessed using a descending span and 2N-back audio tests. Our study showed poorer working memory scores in both tests among individuals with stuttering (p<0.05). The reduced score could be due to a problem using top-down processing skills among adults with stutters. Attention and concentration are the primary skills that are required for memory. Increased anxiety during greater attentional demands (as the cognitive load increases) is seen in individuals with stuttering, and dysfluencies caused by the stuttering could have hampered the attentional demands necessary for the task.[32] The increased anxiety could be the possible reason for poorer performance. In addition, it could also be due to a poorer representation of the phonological loop in adults with stutters.[33] The result of our study supports the findings reported in the literature.[34]

Recent neuroimaging and electrophysiological studies have provided strong evidence for structural and functional abnormalities in key brain regions involved in auditory and motor functions, such as the auditory cortex, basal ganglia, and motor areas.[35-37] These abnormalities contribute to the auditory and motor dysfunctions often observed in individuals who stutter. The findings from our study are consistent with this body of research, suggesting that stuttering is linked to deficits in auditory processing and working memory, pointing to more generalized neurocognitive difficulties. Atypical activation patterns in the auditory system, including abnormal mismatch negativity responses and impaired auditory temporal processing, indicate a disruption in auditory-motor integration.[38] Additionally, studies examining brainstem responses, particularly ABRs, suggest that central auditory deficits may contribute to the timing challenges in speech production and perception.[39] Together, these findings underscore the intricate neurocognitive mechanisms underlying stuttering, emphasising the critical role of the auditory system in its manifestation.

The findings from this study have several clinical implications for the assessment and treatment of individuals with stuttering. The observed deficits in binaural processing, both at the brainstem and cortical levels, suggest that auditory processing abnormalities may contribute to the speech difficulties experienced by individuals with stuttering. Clinicians should consider incorporating comprehensive auditory processing assessments into routine clinical evaluations for individuals with stuttering. This could include tests for ITDs, ILDs, and binaural integration (e.g., dichotic listening tasks), which may help identify underlying auditory processing deficits that could be affecting speech perception and production.

The results also highlight the importance of assessing auditory working memory in stuttering patients, as reduced performance in working memory tasks was found. Clinicians should be aware that individuals with stuttering may experience challenges with tasks that require attention, concentration, and the processing of auditory information. Tailoring interventions that address these cognitive aspects, such as using memory strategies or providing environments with lower cognitive load, could improve the overall therapeutic outcomes.

Finally, the study emphasises the need for a holistic, multidisciplinary approach to treating stuttering. Given the complexity of the condition and its potential impact on both auditory processing and cognitive functions, speech-language pathologists, audiologists, and cognitive therapists should collaborate to develop comprehensive treatment plans that incorporate auditory processing and working memory assessments alongside traditional speech therapy. This approach could enhance therapeutic interventions, address underlying cognitive deficits, and ultimately improve communication outcomes for individuals with stuttering.

Limitations of the study and future directions

A few limitations must be considered when interpreting the findings of this study. First, due to the relatively small sample size, it was not feasible to evaluate binaural processing abilities in stuttering individuals based on severity levels (mild, moderate, severe). The moderate severity group, in particular, consisted of a limited number of participants, which hindered the ability to conduct statistical analyses with adequate power. Consequently, further research with a larger sample size is needed to explore the impact of stuttering severity on binaural processing skills more comprehensively.

In addition, the study sample was predominantly male (95%), which limited the ability to perform gender-based analyses. This gender imbalance restricts the generalizability of the study’s findings. While practical constraints prevented the inclusion of more female participants, future studies should aim to achieve a more balanced gender representation and investigate potential gender-based effects on auditory processing outcomes.

Moreover, the study primarily relied on behavioural measures, and the lack of objective neurophysiological data, like ABRs or fMRI, limits the interpretation of brainstem and cortical involvement. The inclusion of neurophysiological measures in future research would provide valuable validation for the behavioural findings and contribute to a more nuanced understanding of the underlying neural mechanisms.

Finally, factors such as task familiarity and potential biases or measurement artifacts may have influenced the results. These aspects were not fully explored in the current study but will be addressed in future research to ensure a more thorough examination of the factors that could contribute to the observed findings.

CONCLUSION

The binaural processing test results show that individuals with stuttering have cortical and brainstem auditory processing abnormalities. This kind of processing deficiency may impact the ability to perceive speech. The research will provide a foundation for a clinical investigation of the brain functioning of individuals with stuttering. Likewise, the working memory test results indicated that individuals with stuttering had lower auditory working memory abilities. Our study’s findings encourage clinicians to create evaluation procedures that include working memory and binaural processing tests for stuttering patients.

Acknowledgments

The authors acknowledge the Director of the All India Institute of Speech and Hearing for allowing the carrying out of this study. The authors acknowledge the participants for their cooperation.

Ethical approval

The research/study approved by Institutional Review Board at All India Institute of Speech, Language, and Hearing Science, number SH/ERB/2022-23/47, dated 5th March 2022.

Declaration of patient consent

Patient’s consent not required as patients identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

References

  1. , ed. Stuttering: An integrated approach to its nature and treatment. Wolter Kluwer; .
  2. , . A Handbook on Stuttering, 6th ed., O. Bloodstein, N. Bernstein Ratner Delmar Learning, Clifton Park, NY (2008), 552 pp., Softcover. J Fluency Disord. 2009;34:295-9.
    [Google Scholar]
  3. , , , , , , et al. Aberrant auditory processing and atypical planum temporale in developmental stuttering. Neurology. 2004;63:1640-6.
    [CrossRef] [Google Scholar]
  4. , , , . Structural and functional abnormalities of the motor system in developmental stuttering. Brain. 2008;131:50-9.
    [PubMed] [Google Scholar]
  5. , , , , , , et al. Corpus callosum differences associated with persistent stuttering in adults. J Commun Disord. 2011;44:470-7.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  6. , , , , . An update on professional education and clinical practices in central auditory processing. J Am Acad Audiol. 2007;18:428-52.
    [CrossRef] [PubMed] [Google Scholar]
  7. , , , . Assessment of the binaural interaction component of the auditory brain stem response in children with stuttering. Egyptian Journal of Ear, Nose, Throat and Allied Sciences. 2022;23:1-8.
    [CrossRef] [Google Scholar]
  8. , , . What is the role of auditory processing in stuttering? A mini review of previous knowledge. Hear Balance Commun. 2022;20:1-7.
    [CrossRef] [Google Scholar]
  9. , , , . [Behavioral auditory processing evaluation in individuals with stuttering] Pro Fono. 2008;20:43-8.
    [CrossRef] [PubMed] [Google Scholar]
  10. , , , , , . Temporal processing and long-latency auditory evoked potential in stutterers. Braz J Otorhinolaryngol. 2017;83:142-6.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  11. , , , , . Auditory temporal processing assessment in children with developmental stuttering. Int J Pediatr Otorhinolaryngol. 2020;132:109935.
    [CrossRef] [PubMed] [Google Scholar]
  12. , . A tale of two corporations: Managing uncertainty during organizational change. Hum Resour Manage. 1998;37:295-303.
    [CrossRef] [Google Scholar]
  13. , . Visibility graph analysis of speech evoked auditory brainstem response in persistent developmental stuttering. Neurosci Lett. 2019;696:28-32.
    [CrossRef] [PubMed] [Google Scholar]
  14. , , . A comparison of stutterers and nonstutterers on masking level differences and synthetic sentence identification tasks. J Commun Disord. 1987;20:379-90.
    [CrossRef] [PubMed] [Google Scholar]
  15. . [Sound localization cues of binaural hearing] Laryngorhinootologie. 2003;82:240-8.
    [CrossRef] [PubMed] [Google Scholar]
  16. , , , . Adaptation of binaural processing in the adult brainstem induced by ambient noise. J Neurosci. 2012;32:462-73.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  17. , , . An exploration of dichotic listening among adults who stutter. Clin Linguist Phon. 2013;27:681-93.
    [CrossRef] [PubMed] [Google Scholar]
  18. . Cognitive processing load as a determinant of stuttering: Summary of a research programme. Clin Linguist Phon. 2006;20:371-85.
    [CrossRef] [PubMed] [Google Scholar]
  19. . Working memory: looking back and looking forward. Nat Rev Neurosci. 2003;4:829-39.
    [CrossRef] [PubMed] [Google Scholar]
  20. , , , , . Judgment of disfluency in people who stutter and people who do not stutter: Results from magnitude estimation. Lang Speech. 2005;48:299-312.
    [CrossRef] [PubMed] [Google Scholar]
  21. . Working memory involvement in stuttering: Exploring the evidence and research implications. J Fluency Disord. 2007;32:218-38.
    [CrossRef] [PubMed] [Google Scholar]
  22. , , , . G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39:175-91.
    [CrossRef] [PubMed] [Google Scholar]
  23. , , , . Tympanometric screening norms for adults. Am J Audiol. 1998;7:55-60.
    [CrossRef] [PubMed] [Google Scholar]
  24. , . Stuttering severity instrument (4th ed). London (England): PRO-ED, an International Publisher; . p. :15-22.
  25. , . Psychoacoustics: a comprehensive MATLAB toolbox for auditory testing. Front Psychol. 2014;5:712.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  26. . Stuttering. J Speech Hear Disord. 1977;42:148-51.
    [CrossRef] [PubMed] [Google Scholar]
  27. , , . Sound localization ability of normal, stuttering, neurotic, and hemiplegic subjects. AMA Arch Gen Psychiatry. 1959;1:640-5.
    [CrossRef] [PubMed] [Google Scholar]
  28. , . Effect of training on dichotic CV and dichotic digit scores. J Indian Speech Hear Assoc. 2009;23:74-80.
    [Google Scholar]
  29. , , , . A review of brain circuitries involved in stuttering. Front Hum Neurosci. 2014;8:884.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  30. , , , . Voxel-based morphometry of auditory and speech-related cortex in stutterers. Neuroreport. 2007;18:1257-60.
    [CrossRef] [PubMed] [Google Scholar]
  31. . Functional and Structural Abnormalities Underlying Left Ear vs. Right Ear Advantage in Dichotic Listening: an fMRI and DTI Study. University of Cincinnati; . Available from: https://www.proquest.com/docview/1636533234?pq-origsite=gscholar&fromopenview=true&sourcetype=Dissertations%20&%20Theses. [Last accessed 2023 September 08]
  32. , , , , , , et al. Avoidance of eye gaze by adults who stutter. J Fluency Disord. 2012;37:263-74.
    [CrossRef] [PubMed] [Google Scholar]
  33. , . Stuttering and natural speech processing of semantic and syntactic constraints on verbs. J Speech Lang Hear Res. 2008;51:1058-71.
    [CrossRef] [PubMed] [PubMed Central] [Google Scholar]
  34. , , . Behavioral and neural correlates of auditory n-back task in adults with and without stuttering. Am J Audiol. 2019;28:471-82.
    [PubMed] [Google Scholar]
  35. , , , , , , et al. Altered patterns of cerebral activity during speech and language production in developmental stuttering An H2(15)O positron emission tomography study. Brain. 1997;120:761-84.
    [CrossRef] [PubMed] [Google Scholar]
  36. , , , , , , et al. A PET study of the neural systems of stuttering. Nature. 1996;382:158-61.
    [CrossRef] [PubMed] [Google Scholar]
  37. , , . Central auditory processing abilities in individuals with tinnitus and normal hearing sensitivity: a systematic review. Egypt J Otolaryngol. 2023;39:126.
    [CrossRef] [Google Scholar]
  38. , , , . Abnormal speech sound representation in persistent developmental stuttering. Neurology. 2005;65:1246-52.
    [CrossRef] [PubMed] [Google Scholar]
  39. , , , , . Evoked potentials and electroencephalography in stuttering. Folia Phoniatr Logop. 2000;52:178-86.
    [CrossRef] [PubMed] [Google Scholar]

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