Development and validation of a novel Context-Based Prospective Memory Task among neurotypical adults.

PURPOSE: To address the paucity and potential of context-based prospective memory (PM) assessment tasks suitable to Indian ethnicity, the study aimed to develop a novel context-based PM task and determine its psychometric properties among neurotypical adults. METHODS: Rendered images in 2-D were extracted from a 3-D shopping mall, where PM and ongoing tasks were embedded within them to provide participants with a semi-immersive experience. The design and scoring of the novel task were constructed in alignment with the Memory for Intentions Screening Test. Fifty neurotypical adults in and around Mangaluru were recruited. The Memory of Intentions Test (MIST) and novel context-based PM task were administered. RESULTS: The validity of the novel task was established with a Content Validity Index of 0.98. The intraclass correlation for the test-retest reliability of the novel context-based PM task was 0.92 (p<0.001) and the inter-rater reliability was 0.98 (p<0.001). The internal consistency of the six subscales was high (Cronbach's α= 0.86), and the Spearman-Brown coefficient indicated a strong split-half reliability of 0.87. Spearman's correlation showed that the trials exhibited strong connections to the dichotomic characteristics of the subscales to which they belonged. Further, McNemar's test suggested similar profiles of the participants for the MIST and novel task. CONCLUSION: The results of the present study suggest that the novel context-based PM task offers good validity and reliability measures, providing valuable insight into the mechanisms of PM, and therefore, could be ideal for inclusion in a battery of cognitive assessments.

Communication-related aspects of prospective memory: an exploratory factor analysis of prospective memory questionnaires.

PURPOSE: Prospective memory (PM) questionnaires are frequently used to evaluate perceptions of PM skills in daily life. This study aimed to systematically investigate communication-specific attributes using pre-existing PM self-rating questionnaires to inform clinicians and researchers about the role of PM in cognitive communicative evaluations. METHODS: PM-related items from three questionnaires (i.e., Prospective Memory Questionnaire, Comprehensive Assessment of Prospective Memory, and Prospective and Retrospective Memory Questionnaire) were compiled and embedded in Google Forms and distributed to 70 Speech-Language Pathologists (SLPs) with expertise in Cognitive Communicative Disorders across India. Participants first identified items related to communication, and were then contacted to rate the communication-related PM items using a Likert scale for their degree of appropriateness. Responses from 40 SLPs were obtained and subjected to item-content validity index (i-CVI) and exploratory factor analysis (EFA). RESULTS: Of the 114 PM items, 28 received ratings over 50% for their relevance to communication. Of the 28 items, 21 had an i-CVI score greater than 0.8. After the removal of overlapping content, 14 items were finalized and subjected to EFA, which resulted in four factors: PM failure due to loss of communicative content, PM failure due to loss of communicative intent, PM cost due to ongoing interference, and PM failure linked to the priority of communicative intent. CONCLUSION: This study highlights communication-related aspects of PM that can be used as a framework for SLPs to assess and research PM skills.

Effect of inter-aural temporal envelope differences on inter-aural time difference thresholds for amplitude modulated noise.

PURPOSE: The inter-aural time difference (ITD) and inter-aural level difference (ILD) are important acoustic cues for horizontal localization and spatial release from masking. These cues are encoded based on inter-aural comparisons of tonotopically matched binaural inputs. Therefore, binaural coherence or the interaural spectro-temporal similarity is a pre-requisite for encoding ITD and ILD. The modulation depth of envelope is an important envelope characteristic that helps in encoding the envelope-ITD. However, inter-aural difference in modulation depth can result in reduced binaural coherence and poor representation of binaural cues as in the case with reverberation, noise and compression in cochlear implants and hearing aids. This study investigated the effect of inter-aural modulation depth difference on the ITD thresholds for an amplitude-modulated noise in normal hearing young adults. METHODS: An amplitude modulated high pass filtered noise with varying modulation depth differences was presented sequentially through headphones. In one ear, the modulation depth was retained at 90% and in the other ear it varied from 90% to 50%. The ITD thresholds for modulation frequencies of 8 Hz and 16 Hz were estimated as a function of the inter-aural modulation depth difference. RESULTS: The Friedman test findings revealed a statistically significant increase in the ITD threshold with an increase in the inter-aural modulation depth difference for 8 Hz and 16 Hz. CONCLUSION: The results indicate that the inter-aural differences in the modulation depth negatively impact ITD perception for an amplitude-modulated high pass filtered noise.

Effect of inter-aural temporal envelope differences on inter-aural time difference thresholds for amplitude modulated noise

ABSTRACT Purpose The inter-aural time difference (ITD) and inter-aural level difference (ILD) are important acoustic cues for horizontal localization and spatial release from masking. These cues are encoded based on inter-aural comparisons of tonotopically matched binaural inputs. Therefore, binaural coherence or the interaural spectro-temporal similarity is a pre-requisite for encoding ITD and ILD. The modulation depth of envelope is an important envelope characteristic that helps in encoding the envelope-ITD. However, inter-aural difference in modulation depth can result in reduced binaural coherence and poor representation of binaural cues as in the case with reverberation, noise and compression in cochlear implants and hearing aids. This study investigated the effect of inter-aural modulation depth difference on the ITD thresholds for an amplitude-modulated noise in normal hearing young adults. Methods An amplitude modulated high pass filtered noise with varying modulation depth differences was presented sequentially through headphones. In one ear, the modulation depth was retained at 90% and in the other ear it varied from 90% to 50%. The ITD thresholds for modulation frequencies of 8 Hz and 16 Hz were estimated as a function of the inter-aural modulation depth difference. Results The Friedman test findings revealed a statistically significant increase in the ITD threshold with an increase in the inter-aural modulation depth difference for 8 Hz and 16 Hz. Conclusion The results indicate that the inter-aural differences in the modulation depth negatively impact ITD perception for an amplitude-modulated high pass filtered noise.

Development and validation of a novel Context-Based Prospective Memory Task among neurotypical adults

ABSTRACT Purpose To address the paucity and potential of context-based prospective memory (PM) assessment tasks suitable to Indian ethnicity, the study aimed to develop a novel context-based PM task and determine its psychometric properties among neurotypical adults. Methods Rendered images in 2-D were extracted from a 3-D shopping mall, where PM and ongoing tasks were embedded within them to provide participants with a semi-immersive experience. The design and scoring of the novel task were constructed in alignment with the Memory for Intentions Screening Test. Fifty neurotypical adults in and around Mangaluru were recruited. The Memory of Intentions Test (MIST) and novel context-based PM task were administered. Results The validity of the novel task was established with a Content Validity Index of 0.98. The intraclass correlation for the test-retest reliability of the novel context-based PM task was 0.92 (p<0.001) and the inter-rater reliability was 0.98 (p<0.001). The internal consistency of the six subscales was high (Cronbach's α= 0.86), and the Spearman-Brown coefficient indicated a strong split-half reliability of 0.87. Spearman's correlation showed that the trials exhibited strong connections to the dichotomic characteristics of the subscales to which they belonged. Further, McNemar's test suggested similar profiles of the participants for the MIST and novel task. Conclusion The results of the present study suggest that the novel context-based PM task offers good validity and reliability measures, providing valuable insight into the mechanisms of PM, and therefore, could be ideal for inclusion in a battery of cognitive assessments.

Communication-related aspects of prospective memory: an exploratory factor analysis of prospective memory questionnaires

ABSTRACT Purpose Prospective memory (PM) questionnaires are frequently used to evaluate perceptions of PM skills in daily life. This study aimed to systematically investigate communication-specific attributes using pre-existing PM self-rating questionnaires to inform clinicians and researchers about the role of PM in cognitive communicative evaluations. Methods PM-related items from three questionnaires (i.e., Prospective Memory Questionnaire, Comprehensive Assessment of Prospective Memory, and Prospective and Retrospective Memory Questionnaire) were compiled and embedded in Google Forms and distributed to 70 Speech-Language Pathologists (SLPs) with expertise in Cognitive Communicative Disorders across India. Participants first identified items related to communication, and were then contacted to rate the communication-related PM items using a Likert scale for their degree of appropriateness. Responses from 40 SLPs were obtained and subjected to item-content validity index (i-CVI) and exploratory factor analysis (EFA). Results Of the 114 PM items, 28 received ratings over 50% for their relevance to communication. Of the 28 items, 21 had an i-CVI score greater than 0.8. After the removal of overlapping content, 14 items were finalized and subjected to EFA, which resulted in four factors: PM failure due to loss of communicative content, PM failure due to loss of communicative intent, PM cost due to ongoing interference, and PM failure linked to the priority of communicative intent. Conclusion This study highlights communication-related aspects of PM that can be used as a framework for SLPs to assess and research PM skills.

A Delphi survey-based development and validation of cognitive-communication assessment tool for Indian preschoolers

ABSTRACT Purpose To address the need for a standardized assessment tool for assessing cognitive-communication abilities among Indian preschoolers, the current study aimed at describing a Delphi based development and validation process for developing one such tool. The objectives of the research were to conceptualize and construct the tool, validate its content, and assess its feasibility through pilot testing. Methods The study followed a Delphi approach to develop and validate the tool across four phases i.e. conceptualization; construction; content validation; and pilot testing. The first three phases were performed with a panel of six experts including speech-language pathologists and preschool teachers while the pilot testing was done with 20 typically developing preschoolers. A literature review was also conducted with the Delphi rounds to support the developmental process. Results The first two rounds of the Delphi aided in the construction of a culturally and linguistically suitable story-based cognitive-communication assessment tool with the memory (free recall, recognition, and literary recall) and executive function (reasoning, inhibition, and switching) related tasks relevant for preschoolers. The content validation of the tool was continued with the experts till the revisions were satisfactory and yielded an optimum Content Validity Index. The pilot test of the finalized version confirmed its feasibility and appropriateness to assess developmental changes in the cognitive-communication abilities of preschoolers. Conclusion The study describes the Delphi-based conceptualization, construction, content validation, and feasibility check of a tool to assess cognitive-communication skills in preschool children.

A Delphi survey-based development and validation of cognitive-communication assessment tool for Indian preschoolers.

PURPOSE: To address the need for a standardized assessment tool for assessing cognitive-communication abilities among Indian preschoolers, the current study aimed at describing a Delphi based development and validation process for developing one such tool. The objectives of the research were to conceptualize and construct the tool, validate its content, and assess its feasibility through pilot testing. METHODS: The study followed a Delphi approach to develop and validate the tool across four phases i.e. conceptualization; construction; content validation; and pilot testing. The first three phases were performed with a panel of six experts including speech-language pathologists and preschool teachers while the pilot testing was done with 20 typically developing preschoolers. A literature review was also conducted with the Delphi rounds to support the developmental process. RESULTS: The first two rounds of the Delphi aided in the construction of a culturally and linguistically suitable story-based cognitive-communication assessment tool with the memory (free recall, recognition, and literary recall) and executive function (reasoning, inhibition, and switching) related tasks relevant for preschoolers. The content validation of the tool was continued with the experts till the revisions were satisfactory and yielded an optimum Content Validity Index. The pilot test of the finalized version confirmed its feasibility and appropriateness to assess developmental changes in the cognitive-communication abilities of preschoolers. CONCLUSION: The study describes the Delphi-based conceptualization, construction, content validation, and feasibility check of a tool to assess cognitive-communication skills in preschool children.

Development and validation of educational multimedia to promote public health literacy about healthy cognitive aging.

OBJECTIVES: Health literacy (HL) about healthy cognitive aging is essential in preventing cognitive decline and promoting cognitive well-being. It is important that one such HL module should be scientifically designed, delivered in a technically sound manner to the audience, and specific to the context. The present study thus aimed at developing and validating educational multimedia about cognitive health. METHODS: The study followed a methodological framework and was carried out across three phases, that is, identification of themes, development and validation of educational script and design, and validation of educational multimedia. The module was scripted based on the Integrated HL framework and the recommendations made during the modified nominal group technique among the research team. Seven speech-language pathologists (SLPs), with expertise in the field of cognitive sciences, and 15 representatives of the general public validated the module using the Educational Content Validation Instrument in Health and the Patient Education Materials Assessment Tool for Audiovisual Materials questionnaire. RESULTS: The scientific content of the educational script received satisfactory agreements among the experts (content validity index [CVI]: 0.93) and representatives of the general public (CVI: 0.86). The technical aspects of the educational multimedia were rated to have high understandability (experts: 92.8%; representatives of general public: 98.8%) and actionability (experts and representatives of general public 100%). CONCLUSION: Overall, the developed educational multimedia scored optimally with respect to the objective, structure, relevance of the content, actionability and understandability of the multimedia. The developed module holds the potential to be used at community and national level health educational programs or awareness campaigns to enhance public knowledge and beliefs pertaining to cognitive health. PATIENT OR PUBLIC CONTRIBUTION: SLPs with expertise in the field of cognitive science and representatives from the general public were included to validate and obtain feedback on the developed educational multimedia.

Normative data for certain vocal fold biomarkers among young normophonic adults using ultrasonography.

PURPOSE: The current study aimed to profile vocal fold morphology, vocal fold symmetry, gender and task-specific data for vocal fold length (VFL) and vocal fold displacement velocity (VFDV) in young normophonic adults in the age range of 18-30 years using ultrasonography (USG). METHODS: Participants underwent USG across quiet breathing, /a/ phonation and /i/ phonation tasks, and acoustic analysis was conducted to explore the relationship between USG and acoustic measures. RESULTS: The study found that males have longer vocal folds than females, and overall greater velocities were observed in /a/ phonation, followed by /i/ phonation, with the lowest velocity observed in the quiet breathing task. CONCLUSIONS: The obtained norms can be used as a quantitative benchmark for analyzing the vocal fold behavior in young adults.

Effect of interaural electrode insertion depth difference and independent band selection on sentence recognition in noise and spatial release from masking in simulated bilateral cochlear implant listening.

PURPOSE: Inter-aural insertion depth difference (IEDD) in bilateral cochlear implant (BiCI) with continuous interleaved sampling (CIS) processing is known to reduce the recognition of speech in noise and spatial release from masking (SRM). However, the independent channel selection in the 'n-of-m' sound coding strategy might have a different effect on speech recognition and SRM when compared to the effects of IEDD in CIS-based findings. This study aimed to investigate the effect of bilateral 'n-of-m' processing strategy and interaural electrode insertion depth difference on speech recognition in noise and SRM under conditions that simulated bilateral cochlear implant listening. METHODS: Five young adults with normal hearing sensitivity participated in the study. The target sentences were spatially filtered to originate from 0° and the masker was spatially filtered at 0°, 15°, 37.5°, and 90° using the Oldenburg head-related transfer function database for behind the ear microphone. A 22-channel sine wave vocoder processing based on 'n-of-m' processing was applied to the spatialized target-masker mixture, in each ear. The perceptual experiment involved a test of speech recognition in noise under one co-located condition (target and masker at 0°) and three spatially separated conditions (target at 0°, masker at 15°, 37.5°, or 90° to the right ear). RESULTS: The results were analyzed using a three-way repeated measure analysis of variance (ANOVA). The effect of interaural insertion depth difference (F (2,8) = 3.145, p = 0.098, ɳ2 = 0.007) and spatial separation between target and masker (F (3,12) = 1.239, p = 0.339, ɳ2 = 0.004) on speech recognition in noise was not significant. CONCLUSIONS: Speech recognition in noise and SRM were not affected by IEDD ≤ 3 mm. Bilateral 'n-of-m' processing resulted in reduced speech recognition in noise and SRM.

A system for spatial hearing research.

The spatial hearing experiments can be simulated using high-fidelity headphones. But these simulated experiments do not account for individual variations and are difficult to investigate when the listener is wearing hearing devices. Hence, the free-field systems are ideal for spatial hearing experiments. However, these systems are not readily available and must be customized based on experimental needs. This paper provides a brief overview of a spatial hearing research facility that is customized to perform experiments on individuals with normal hearing and hearing aid users. •This setup enables the assessment of spatial acuity with 10° precision in the horizontal plane.•The laboratory's universal design enables modifications based on experimental needs with minimum effort.•The signal processing and response acquisition systems are custom designed using MATLAB.

Can Straw Phonation Be Considered As Vocal Warm Up Among Speech Language Pathologists?

OBJECTIVE: Straw phonation exercises have been proved to be effective in improving voice quality among persons with voice pathology. The aim of the study was to investigate the effects of straw phonation as a warm-up exercise on maximum phonation duration, acoustic, and perceptual parameters of voice among Speech Language Pathologists. STUDY DESIGN: The study adopted a pretest-posttest design. MATERIALS AND METHOD: Twenty-five females with the mean age range of 20.87 ± 1.15 years participated in the study and completed a series of straw phonation exercises for three cycles. Maximum phonation duration, acoustic, and self-perceptual measures were assessed before and after the straw phonation exercises. F0, jitter, shimmer, nose to harmonic ratio, intensity, F1, F2, F3, F4, Maximum phonation duration, and the post self-perceptual measures were analyzed. RESULTS: The results indicated a significant improvement in the F0, intensity, F1, F2, F4, Maximum phonation duration, and self-perceptual measures. CONCLUSION: Straw phonation exercises provides an easy and effective warm up technique to improve the voice quality among Speech Language Pathologists and can be considered before conducting therapy sessions.

Immediate effects of 'Ujjayi Pranayama' on aerodynamic, acoustic and self perception parameters of voice in teachers.

BACKGROUND: Voice plays a major role in communication, and it reveals the speaker's physical and emotional health, personality, and identity. Professional voice users are dependent on their voice for their livelihood. A minimal change or deviation in their voice can interfere with their career. Since respiration is the source for voice production, good lung capacity and the inspiratory-expiratory ratio are very important in maintaining a good voice quality. Ujjayi Pranayama, an effective breathing technique is targeted in this study. OBJECTIVE: To investigate the immediate effects of Ujjayi pranayama on acoustic, aerodynamic and self-perception parameters of voice in teachers. METHOD: Twenty normophonic female teachers performed this breathing technique taught by yoga professional. Parameters of aerodynamic, acoustic, and self-perception were analyzed at pre and post-practice. RESULTS: Significant differences in the acoustic variables including intensity and jitter were observed. Aerodynamic parameters have shown significant improvements in the variables including Maximum phonation Duration (MPD), Estimated Subglottal Pressure (ESGP), Laryngeal Conductance (LAC), Laryngeal Resistance (LAR) and Sound Pressure Level (SPL). Among the study participants, 80% have rated the Ujjayi pranayama as useful in prepping their voice for the vocal loading tasks. CONCLUSION: In view of the better objective evidence and significant improvements in the study variables including the participant's self-perception, authors suggest that Ujjayi pranayama can also be used in voice rehabilitation as a vocal warm-up exercise.

Relationship between parental report of language skills and children's performance among 3-year-olds: Implications for screening language among preschoolers.

AIM: The study compared parental ratings of children's language abilities at 3-years of age with observations of children's language performance by Speech Language Pathologists (SLPs). METHOD: Children (n=85) around 3-years of age were recruited from a child development clinic. Detailed speech and language assessments were completed during a one-hour semi-structured clinician-child interactive session. Language assessment was carried out using a criterion-referenced checklist and the language sections of the Bayley Scale for Infant Development- 3rd Edition (BSID-III). All parents rated their children's language skills using seven statements related to reception and expression domains of language on a 7-point rating scale. The language status of the child (typical language vs delay) determined by the parental report was matched with the language status as per the child's performance during the SLP assessment. RESULTS AND DISCUSSION: Mean parental ratings of children assessed as having language delay by an SLP were significantly lower than children with typical language. Total parental rating score correlated highly with overall language scores on BSID-III; the highest correlation was observed for ratings of statements related to expressive language skills focusing on formation of sentences. Parental report of below normal performance on any one of the seven statements demonstrated acceptable sensitivity (0.95) and a high negative predictive value (0.98) with the child's performance as the gold standard. CONCLUSION: Parental ratings of language skills correlated with child's performance at 3-years of age with a higher agreement for identifying children with delays. Parental reports can be useful to red-flag children for further assessment and continued monitoring of language development in busy developmental clinics and preschools, especially in the context of low-resource settings.

Child, Parent, and Play - An Insight into These Dimensions Among Children with and without Receptive Expressive Language Disorder Using Video-Based Analysis.

PURPOSE: Language development in children aged 3-6 years is shaped by their pre-linguistic abilities, communication patterns and play behaviors along with parental communicative roles. Little is known about how these aspects are distributed among children with receptive expressive language disorder (CWRELD) in comparison to typically developing children (CWTDL). The present research explores these differences between the two groups using a video-based analysis with a belief that an understanding of these aspects may facilitate age-appropriate speech and language acquisition in children with language delay. METHODS: A video-based analysis of parent-child interactions was carried out for 10 children each with receptive expressive language disorder and typical language development, respectively. The two groups were compared for the child's turn-taking skills, eye contact span, autonomous instances, communication patterns, play behaviors and parental communication roles. RESULTS: Children with receptive expressive language disorder exhibited significantly fewer proportion of turns and autonomous instances along with a greater proportion of eye contact to objects than the parent. Majority of the children with language delay were at the "Requester" or "Early communicators" stage and demonstrated either "Exploratory" or "Functional play" behaviors. Most of the typically developing children were at the "Partner stage" of communication and exhibited "Functional", "Constructive" or "Symbolic Play". Parents of children with language delay mostly exhibited "Helper" type communicative roles while parents from typically developing groups showed "Partner" type communicative profile. CONCLUSION: A quantitative planning and monitoring of pre-linguistic skills, determination of communicative patterns and play behaviors is important for clinicians working with children having a language delay. Assessing and modifying parental communicative roles are also crucial. Understanding the distribution of these research variables among CWRELD in comparison to CWTDL may help clinicians in planning precise treatment goals, monitoring specific linguistic progress, ensuring better parental participation and delivering better outcomes during language therapy.

Effect of Sudarsankriya yoga practices on P300 amplitude and latency.

The cognitive ability which was perceived as a constant trait, is now understood to be upgraded by adaptive and extended training. Yoga practices are known to sharpen the intellect and enhance concentration. In the initial period of practicing yoga as an alternative/supporting tool to medical line of treatment, it is essential to investigate effect of yoga on cognitive ability using objective method, in order to establish evidences. Hence, aim of this study was to explore the effect of regular practice of sudarsankriya yoga on auditory event related potential (P300) by recording and comparing peak latency and amplitude. The participants were divided into three groups with Group I and Group II participants practicing sudarsankriya yoga for more than 36 months and less than 36 months respectively. Group III were non-practitioners with no prior practice of any form of yoga. Twenty participants in each group with a total of 60 participants between 40 to 65 years of age were recruited for the study. Results revealed a significant difference for mean latency and amplitude between three groups. Findings of the current study suggest that sudarsankriya yoga practices slows down the process of aging effect or maintains on cognitive ability in adults.

Kannada akshara knowledge in primary school children: measurement of accuracy and reaction time using a cross-sectional study design.

Background: Reading acquisition varies between languages, as languages differ in terms of phonology and orthography. Orthographic knowledge is demonstrated to be crucial in literacy acquisition in most orthographies. The literature on acquisition of orthographic knowledge has focused more on alphabetic orthographies and less is understood in alphasyllabary Kannada language. The present study aimed to understand the akshara knowledge acquisition by measuring akshara identification accuracy and reaction time in typically developing Kannada medium primary school children. Methods: The study consisted of 315 typically developing children, 45 each from Grade I through Grade VII between the age range of 5 years 6 months to 12 years 6 months. The children were assessed for akshara identification accuracy and reaction time using a representative sample of 67 akshara selected at four different levels of complexity: vowels in primary form, consonant with inherent vowels, consonant with vowel diacritics, and consonant clusters. The mean performance was compared between the groups using one-way ANOVA with post-hoc Bonferroni test. Results: One-way ANOVA revealed significant main effect (p≤0.05) of Grade on akshara identification accuracy and reaction time. The post-hoc Bonferroni test revealed that the mean akshara identification accuracy improved significantly (p≤0.05) from Grade I to Grade V and reached a plateau at Grade VI. The reaction time significantly reduced from Grade I to Grade IV and there was no significant change beyond Grade V.    Conclusion: The children learning to read alphasyllabary Kannada gain mastery over the majority of aksharas during the initial years of formal schooling, which develops completely by Grade VI. The automaticity in naming akshara develops gradually and reaches a plateau by Grade IV. The present findings indicate that children acquire automaticity in naming akshara early, while the akshara knowledge continues to develop.

Effect of inter-aural modulation depth difference on interaural time difference thresholds for speech: An observational study.

Background: The temporal envelope (ENV) plays a vital role in conveying inter-aural time difference (ITD) in many clinical populations. However, the presence of background noise and electronic features, such as compression, reduces the modulation depth of ENV to a different degree in both ears. The effect of ENV modulation depth differences between the ears on ITD thresholds is unknown; therefore, this was the aim of the current study's investigation. Methods: Six normally hearing young adults (age range 20-30 years) participated in the current study. Six vowel-consonant-vowel (VCV) (/aka/, /aga/, /apa/, /aba/, /ata/, /ada/) tokens were used as the probe stimuli. ENV depth of VCV tokens was smeared by 0%, 29%, and 50%, which results in 100%, 71%, and 50% of the original modulation depth. ITD thresholds were estimated as a function of the difference in temporal ENV depth between the ears, wherein in one ear the modulation depth was retained at 100% and in the other ear, the modulation depth was changed to 100%, 71%, and 50%. Results: Repeated measures of ANOVA revealed a significant main effect of interaural modulation depth differences on the ITD threshold (F(2,10)= 9.04, p= 0.006). ITD thresholds increased with an increase in the inter-aural modulation depth difference. Conclusion: Inter-aural ENV depth is critical for ITD perception.