Gap Thresholds Research Articles

Reliability of preoperative gel foam patch test in predicting postoperative hearing outcome

Aim: This study aims to know the correlation between the preoperative gel foam patch test with the postoperative hearing outcome. Objectives: The objective is to correlate and compare the air-bone gap (ABG) and mean hearing thresholds obtained at frequencies 500 Hz, 1 KHz, 2 KHz, and 4 KHz through audiological evaluation preoperatively, immediately after gelfoam application and 2 months postoperatively (Type I tympanoplasty). Materials and Methods: A total of 124 cases with a mean age of 37 years with a history of chronic otitis media (COM, mucosal type) having medium to large size of central perforation of the tympanic membrane with pure conductive hearing loss participated in this study. Cases were subjected to routine investigations along with a battery of otological investigations. Further, pure-tone audiometric evaluation was performed before gelfoam patch application, immediately after gelfoam patch application and postoperatively after 2 months and the outcomes were compared. Results: Across all four frequencies, ABG was improved and showed a highly significant difference between preoperative mean findings in comparison to patch and postoperative findings. In this study, a strong positive correlation and reliability between patch test hearing thresholds and postoperative hearing thresholds are observed. Comparing preoperative hearing thresholds and postoperative hearing thresholds with student t-test thresholds improved by approx 17 dB hearing loss (17.50645). Conclusion: Hence, this study shows preoperative gel foam patch test in cases of pure conductive hearing loss is reliable in predicting the postoperative hearing outcome. Furthermore helps in convincing and counseling the patients.

Across‐frequency interference in visual temporal gap detection revisited

AbstractPurposeAt EVER2017, we reported that visual detection of a temporal gap becomes difficult when spatial frequency separation is introduced between markers delimiting the gap. In that report, however, gap thresholds were measured separately, in different runs, for within‐frequency and across‐frequency gap detection. Therefore, our previous findings may be simply explained by the effect of spatial‐frequency specific adaptation on visible persistence. Here, we reassessed the across‐frequency interference in gap detection using a procedure uncontaminated by spatial‐frequency specific adaptation.MethodsGaussian‐windowed sinusoidal gratings were used for gap markers. Spatial frequencies of the leading and trailing markers were manipulated to be either 2 or 4 cpd. Gap thresholds were measured using a two‐interval, two‐alternative forced choice method with a two‐down/one‐up interleaved adaptive staircase procedure targeting 70.7% correct detection: Four staircases corresponding to the four combinations of marker frequencies were interleaved in a single run and randomly selected in each trial. Sixteen observers with normal vision completed two runs, and the mean of estimated thresholds between two runs for each condition were subject to analysis.ResultsGap thresholds for across‐frequency markers (2‐4 and 4‐2 conditions) were significantly higher than those for within‐frequency markers (2‐2 and 4‐4 conditions). For within‐frequency gap detection, gap thresholds were significantly higher for 4 cpd than for 2 cpd markers, which was consistent with the well‐known decreased temporal resolution with increasing spatial frequency.ConclusionWe confirmed our previous findings that temporal gaps bounded by different frequency markers are more difficult to detect than those bounded by identical frequency markers. We propose that perceptual discontinuity signaling the frequency separation interferes with gap representation and longer gaps are required for correct gap detection.

<p>Treatment Adherence And Persistence Among HIV-1 Patients Newly Starting Treatment</p>

ObjectiveTo assess adherence and persistence with first-line single-tablet regimen (STR) and multi-tablet regimen (MTR) antiretroviral therapy (ART) in newly treated HIV-1 patients.MethodsRetrospective analysis of longitudinal pharmacy claims among US patients initiating ART between 1/1/2016 and 5/31/2016 (index date was defined by first ART claim for STRs, and fill date for the last therapy in the regimen for MTRs). Adherence was assessed over a 12-month period and reported as the proportion of adherent or non-adherent (defined as ≤5-day and > a 5-day gap between successive fills, respectively) patients. Sensitivity analysis using ≤7-day and ≤14-day gap thresholds to define adherence was performed. Persistence was assessed as the number of days on therapy from index until treatment discontinuation (>90 day gap in therapy). Kaplan–Meier curves and Cox Proportional Hazard models were generated to evaluate discontinuation rates. Assessments were performed on STRs vs MTRs overall and by regimen.ResultsPatients initiating ART (STR: n=10,623; MTR: n=2504) had a mean age of 42.8 years; 76.0% were male. STR patients were >2 times more likely to be adherent over 12 months than MTR patients (24.9% vs 11.7%, respectively). Patients using EVG/COBI/FTC/TAF had greater adherence than those using other STRs. Among MTRs, patients were more adherent with FTC/TDF+DTG (15.1%) than other MTRs. Persistence was also greater with STRs, with MTR patients being 61% more likely to discontinue therapy. Persistence was best for FTC/TAF-based regimens. Predictors of treatment discontinuation included younger age, female gender, and Medicare or Medicaid insurance type.ConclusionPatients receiving STRs were significantly less likely to discontinue therapy and were more adherent with their regimens, providing further evidence of greater adherence and persistence with STRs versus MTRs. However, there was a large proportion of patients who interrupted or discontinued treatment. Further research examining treatment patterns beyond first line is warranted.

Regional Competitiveness Analysis: A Prime Focus on Region's Spatio-Functional Gap and Median Population Threshold Assessment

Counter-balancing the spatio-functional gaps of service facilities is considered to be the foremost task of Regional Planning. The functional gap analysis and median population threshold helps to identify and analyze the adequacy or inadequacy of the services within each complementary region. Therefore, this particular research tries to understand the requirement and availability of socio-economic facilities and its distribution in the optimum location in the study area through the analysis of functional gap and median population threshold. This study deals with several services facilities as growth center, rural market, educational and healthcare facilities like high school, primary school, upazilla health complex, community clinic and so on. As an overall finding the study reveals that, service facilities like community clinic, growth center requires a very small population to be supported whereas facilities like police station, healthcare center do not demand such a high population to be existed. The main reason behind that can be facility like community clinic is of major importance for the people and it is a basic need in comparing to the other supplementary services like police station. In regards of functional gap, the service facilities are inadequate in almost all of the unions and upazillas of Khulna district. Finally, the study concludes to an interesting finding that, though the secondary needs of the people of this region is not served properly, the basic needs of common people is well served in this region.

Evaluating the Utility of Follow-up Radiographs for Isolated Radial Head Fractures Undergoing Initial Nonoperative Treatment.

To evaluate the utility of follow-up radiographs in patients with isolated partial articular radial head fractures (OTA/AO 2R1B1 or 2R1B3). Retrospective cohort study. Academic Level 1 Trauma Center. Adult patients (≥18 years) with isolated partial articular radial head fractures indicated for initial nonoperative treatment. Analysis of elbow radiographs at initial presentation and at postinjury follow-up of 3-8 weeks. Articular gap and step-off. Radiographic articular displacement between initial and follow-up radiographs. For 72 included patients, initial radiographs were obtained on average 2.6 days after injury and follow-up radiographs 33.7 days thereafter. Equivalence tests evaluating gap and step-off thresholds of <1 mm were both significant, indicating that the cohort displaced <1 mm for both parameters between initial and follow-up radiographs. No patients proceeded to surgical treatment following the repeat radiographs. These fractures do not displace in the early postinjury period, as defined as a <1 mm of change in both intra-articular gap and step-off, as compared to initial radiographs. Routine follow-up radiographs for these injuries is a source of cost, but with limited utility in detecting interval displacement or leading to a change in management. Selective use of radiographs to evaluate specific clinical concerns may lead to cost savings. Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Hearing complaints in HIV infection originate in the brain not the ear.

Evidence suggests damage to brain auditory pathways, rather than inner ear damage, underlies the hearing difficulties HIV+ individuals report. But, antiretroviral therapy (ART) may affect the hearing system and also lead to hearing complaints. Longitudinal study of HIV+ and HIV- individuals in Dar es Salaam Tanzania. A subset of this cohort started ART while in the study allowing the effects of ART to be studied directly. The ability to hear quiet sounds (pure-tone audiometry), cochlear outer hair cell function [distortion-product otoacoustic emissions (DPOAEs)], and gaps-in-noise detection thresholds (a central auditory processing test) were assessed at each visit. Visits were scheduled for 6-month intervals, but the number and spacing of visits varied. In the group that started ART while in the study, 107 HIV+ individuals had audiometric thresholds, 98 had DPOAEs, and 98 had gap measurements suitable for analysis. Data were analyzed using a linear mixed model with time and starting ART as fixed effects and individual participant repeated measures as random effects. Starting ART did not affect audiometric or gap detection thresholds. The slope of the DPOAE amplitude vs. time relationship was more negative after starting ART but did not differ from the HIV- group. Gap thresholds were higher in the HIV+ group. ART did not affect audiometric thresholds significantly suggesting common ART drugs are not major ototoxins. The gap detection results from the study show effects on central auditory processing in HIV+ individuals, supporting the origin of HIV-related hearing complaints in the central auditory system.

Thermal decomposition of ammonium perchlorate/exfoliated-graphene and the relationship between activation energy and band gap

ABSTRACTThe thermal decomposition of ammonium perchlorate AP with electrochemically exfoliated graphene flakes (EGF) was studied at different heating rates in nitrogen and the combustion behavior of AP/EGF propellant was evaluated. The exothermic reaction kinetics were studied by simultaneous thermal analysis (STA) in non-isothermal conditions and compare with the thermal decomposition of pure AP applying the same experimental conditions. Using the Kissinger method, the calculated activation energies Ea for the low- and high-temperature exothermic reactions were 87 and 198 kJ/mol for pure AP, contrasting with 91 and 55 kJ/mol obtained from AP with 5 wt% EGF. From our experimental activation energy values together with reported and calculated band gaps Eg, it was found the empirical relationship:where Ea0 corresponds to the activation energy associated with the high-temperature thermal decomposition of pure AP, Eac is the activation energy associated to the high-temperature thermal decomposition of AP-EGF, E0 = 2.7 eV is the catalyst band gap threshold required to activate the electron transfer mechanism and n = 6 is the exponential factor associated to pure AP.

Optical absorption in disordered monolayer molybdenum disulfide

We explore the combined impact of sulfur vacancies and electronic interactions on the optical properties of monolayer MoS$_2$. First, we present a generalized Anderson-Hubbard Hamiltonian that accounts for both randomly distributed sulfur vacancies and the presence of dielectric screening within the material. Second, we parameterize this energy-dependent Hamiltonian from first-principles calculations based on density functional theory and the Green function and screened Coulomb (GW) method. Third, we apply a first-principles-based many-body typical medium method to determine the single-particle electronic structure. Fourth, we solve the Bethe-Salpeter equation to obtain the charge susceptibility $\chi$ with its imaginary part being related to the absorbance $\mathcal{A}$. Our results show that an increased vacancy concentration leads to decreased absorption both in the band continuum and from exciton states within the band gap. We also observe increased absorption below the band gap threshold and present an expression, which describes Lifshitz tails, in excellent qualitative agreement with our numerical calculations. This latter increased absorption in the $1.0$--$2.5$\,eV makes defect engineering of potential interest for solar cell applications.

Toward Optimizing Cervical Vestibular Evoked Myogenic Potentials (cVEMP): Combining Air-Bone Gap and cVEMP Thresholds to Improve Diagnosis of Superior Canal Dehiscence.

To develop a novel approach combining low-frequency air-bone gap (ABG) and cervical vestibular evoked myogenic potential (cVEMP) thresholds to improve screening for superior canal dehiscence (SCD) syndrome. Retrospective study. Tertiary care center. One hundred forty patients with SCD and 21 healthy age-matched controls were included. Ears for each patient were divided into three groups based on computed tomography (CT) findings: 1) dehiscent, 2) thin, or 3) unaffected. cVEMP and audiometric thresholds were analyzed and differences among groups were evaluated. We define the third window indicator (TWI) as the cVEMP thresholds at 500, 750, and 1000 Hz adjusted for the ABG at 250 Hz (i.e., subtracting ABG from cVEMP threshold). The TWI differentiates between dehiscent and nondehiscent control ears with a sensitivity of 82% and specificity of 100%, corresponding to a positive predictive value of 100%. ABGs and cVEMP thresholds were similar for healthy controls and patients with thin bone over the superior canal. This is the largest study to date examining the usefulness of cVEMPs in the diagnosis of SCD. Our "third window indicator" (TWI) combines cVEMP thresholds with the ABG at 250 Hz to improve the ability to screen patients with SCD symptoms.

Automatic identification of near-stationary traffic states based on the PELT changepoint detection

The existence of stationary states during peak periods has been an underlying assumption of many studies on analysis, operations, control, and management of transportation networks. In Cassidy (1998), a method was proposed to manually identify near-stationary states by visually inspecting transformed curves of cumulative total vehicle counts and occupancies. Such near-stationary states are important for calibrating fundamental diagrams, identifying active bottlenecks and incidents, and quantifying capacity drop magnitudes. To the best of our knowledge, however, there lacks an automatic method that can be applied to efficiently identify near-stationary states from a large amount of data.In this study, we attempt to fill this gap. We start with definitions of steady, stationary, and equilibrium states and discuss their relations. Then we present a novel four-step method for automatically identifying near-stationary states from raw loop-detector data: first, the raw data are pre-processed to obtain healthy datasets, fill in missing values, and normalize averaged vehicle counts and occupancies to the same scale; second, daily time series are partitioned into multiple candidate intervals based on the pruned exact linear time (PELT) changepoint detection method; third, the characteristics of the candidate intervals are calculated; and finally, near-stationary states are selected based on modified Cassidy’s gap and duration criteria. We further close the loop by presenting an algorithm to automatically determine the penalty threshold in the second step and the gap threshold in fourth step to ensure the quantity as well as the quality of identified near-stationary states. In a case study, we apply the proposed method to identify near-stationary states from a large set of 30-s raw loop-detector data at a freeway mainline station. We verify the validity of identified near-stationary states both directly and indirectly. The results show that the identified near-stationary states are valid with high quality and the calibrated triangular fundamental diagram is well-fitted and physically meaningful. We finally conclude by discussing some future improvements and potential applications.

Electronic and optical properties of 2H-perovskite related tantalum/niobium oxides

Quasi-one-dimensional oxides [Formula: see text] (A = Ba, Sr; [Formula: see text] = Na, Li and B = Ta, Nb) have been synthesized and found to display efficient photoluminescence. Their electronic and optical properties are calculated by using first-principles calculations. The modified Becke–Johnson exchange potential has been used to obtain accurate band gap. Our results reveal that alkali metal and alkaline-earth metal ions have very small contribution to the states around Fermi level, and for these compounds, the top valence bands and the conduction band bottom are dominated by O-2p and Nb/Ta-d states, respectively. All of these compounds have indirect band gap, with valence band maximum at K point and conduction band minimum at [Formula: see text] point. Optical absorption spectrum is characterized by two prominent peaks. The lower energy peak originates from electron transitions between Ta/Nb-[Formula: see text] and O-2p states, while the higher energy peak is determined by electron transitions between Ta/Nb-[Formula: see text] and O-2p. Despite the one-dimensional feature of the lattice structure, the electronic band structure and optical properties show three-dimensional character. We find that the band gap and optical absorption threshold are considerably larger than the energy of excitation light in the luminescence measurement. This indicates the important role of the in-gap states, which may be induced by the impurity or vacancy.

Across‐frequency impairment in seeing a temporal gap

PurposeTo assess the effects of employing separate spatial frequencies for leading and trailing markers on detection of a temporal gap between the two markers.MethodsTwelve normal observers were tested to measure gap detection thresholds. Gaussian‐windowed sinusoidal gratings were used for markers bounding a gap and thresholds were determined using an adaptive tracking procedure. Spatial frequencies of the leading and the trailing markers were orthogonally manipulated to be either 2 or 4 cpd. The trailing markers were tilted slightly clockwise from the vertical leading markers in order to isolate the effects of frequency change from those of pattern change. In separate blocks of trials, four combinations of the leading and trailing frequencies were tested.ResultsWith markers of identical frequency, gap thresholds were higher for 4 cpd than for 2 cpd markers, replicating well‐established findings of impaired temporal resolution with increasing spatial frequency. Gap thresholds for markers of different frequencies were even higher than the 4‐cpd within‐frequency thresholds.ConclusionsSeeing a temporal gap becomes difficult when spatial frequency change is introduced between gap markers. We propose that temporal processing across different spatial frequency channels leads to impaired gap detection.

Cartilage Ossiculoplasty from Stapes to Tympanic Membrane in One-Stage Intact Canal Wall Tympanoplasty for Cholesteatoma.

To report hearing results of cartilage interposition ossiculoplasty in one-stage intact canal wall (ICW) tympanoplasty for cholesteatoma with intact stapes. A retrospective study of pre and postoperative hearing status was conducted at a tertiary referral otologic center in a series of 61 patients having undergone one-stage ICW tympanoplasty for cholesteatoma with intact stapes and cartilage ossiculoplasty during the same procedure. In the preoperative period, the mean air conduction thresholds (AC), air-bone gap (ABG), and speech reception thresholds (SRT) were 35.3, 20.14, and 35.6 dB, respectively. Postoperatively, with a mean follow-up of 29 months, AC, ABG, and SRT were 27.8, 13.34, and 28.8 dB, respectively. Mean hearing gain was 6.8 dB and mean SRT improvement was 6.8 dB. Mean bone conduction thresholds for 1, 2, and 4 kHz remained stable after surgery (17.6 dB preoperatively vs. 18 dB postoperatively). Cartilage ossiculoplasty from stapes to tympanic membrane in one-stage ICW tympanoplasty for cholesteatoma is a safe, reliable, easy, and effective procedure, with no additional cost.

Revision Stapedectomy with Necrosis of the Long Process of the Incus: Does the Degree of Necrosis Matter? A Retrospective Clinical Study

To discuss the different modalities for managing necrosis of the long process of the incus in revision stapedectomy on the basis of the degree of necrosis and compare the results with those reported in the literature. Thirty-six patients underwent revision stapedectomy with the necrosis of the long process of the incus from 2009 to 2016. The patients were divided into three groups on the basis of the degree of necrosis. For group A (minimal necrosis), augmentation technique with bone cement was performed. For group B (partial necrosis), the cement plug technique was performed. For group C (sever necrosis), malleus relocation with malleovestibulopexy was performed using reshaped necrosed incus. Air and bone conduction thresholds at frequencies of 500-3000 Hz were reviewed pre- and postoperatively using conventional audiometry. The air-bone gap (ABG) and bone conduction thresholds were measured. Postoperative ABG was reduced to <10 dB in 28 cases (77.8%) and <20 dB in all cases (100%). There was no significant change in postoperative bone conduction thresholds. The mean patient follow-up duration was 23 (range, 18-36) months. The cement plug technique was used in 75% of cases. Managing necrosis of the long process of the incus in revision stapedectomy should be considered according to the degree of necrosis. The cement plug technique is considered to be a reasonable option in most cases. Malleus relocation with malleovestibulopexy is an effective alternative to prosthesis.

Spectral and temporal auditory processing in the superior colliculus of aged rats

Presbyacusis reflects dysfunctions present along the central auditory pathway. Given that the topographic representation of the auditory directional spatial map is deteriorated in the superior colliculus of aged animals, therefore, are spectral and temporal auditory processes altered with aging in the rat's superior colliculus? Extracellular single-unit recordings were conducted in the superior colliculus of anesthetized Sprague-Dawley adult (10 months) and aged (22 months) rats. In the spectral domain, level thresholds in aged rats were significantly increased when superior colliculus auditory neurons were stimulated with pure tones or Gaussian noise bursts. The sharpness of the frequency response tuning curve at 10 dB SPL above threshold was also significantly broader among the aged rats. Furthermore, in the temporal domain, the minimal silent gap thresholds to Gaussian noises were significantly longer in aged rats. Hence, these results highlight that spectral and temporal auditory processing in the superior colliculus are impaired during aging.

Investigating time-efficiency of forward masking paradigms for estimating basilar membrane input-output characteristics.

It is well known that pure-tone audiometry does not sufficiently describe individual hearing loss (HL) and that additional measures beyond pure-tone sensitivity might improve the diagnostics of hearing deficits. Specifically, forward masking experiments to estimate basilar-membrane (BM) input-output (I/O) function have been proposed. However, such measures are very time consuming. The present study investigated possible modifications of the temporal masking curve (TMC) paradigm to improve time and measurement efficiency. In experiment 1, estimates of knee point (KP) and compression ratio (CR) of individual BM I/Os were derived without considering the corresponding individual “off-frequency” TMC. While accurate estimation of KPs was possible, it is difficult to ensure that the tested dynamic range is sufficient. Therefore, in experiment 2, a TMC-based paradigm, referred to as the “gap method”, was tested. In contrast to the standard TMC paradigm, the maker level was kept fixed and the “gap threshold” was obtained, such that the masker just masks a low-level (12 dB sensation level) signal. It is argued that this modification allows for better control of the tested stimulus level range, which appears to be the main drawback of the conventional TMC method. The results from the present study were consistent with the literature when estimating KP levels, but showed some limitations regarding the estimation of the CR values. Perspectives and limitations of both approaches are discussed.

Adherence and persistence of mirabegron and anticholinergic therapies in patients with overactive bladder: a real-world claims data analysis.

SummaryBackgroundAdherence and persistence rates of anticholinergic (ACH) therapies have been well described. To date, few studies describe these metrics for mirabegron in patients with overactive bladder.MethodsThis retrospective analysis of MarketScan® database assessed adherence and persistence of patients receiving either mirabegron or ACH. Study eligibility required an index date (first prescription filled) between July 2012 and June 2013 with 12 months of continuous enrolment preindex date and 12 months of follow‐up. Adherence was defined as a proportion of days covered of ≥ 80% among patients with at least 2 fills of index medication. Persistence measures included treatment failure described as either treatment discontinuation (medication supply gap ≥ 30 days) or switching to a different medication. A medication supply gap of ≥ 45 days was used as a sensitivity analysis.ResultsThe mean age of mirabegron users (n = 4037) was 67 years and 43% were ACH naïve while the mean age of ACH users was 62 years (n = 67,943). Over the 12‐month follow‐up period, 44% of patients treated with mirabegron and 31% of patients treated with ACH were adherent to their indexed medications. Treatment failure was 81% for mirabegron and 88% for ACH. Most mirabegron treatment failures were because of treatment discontinuation (67%) versus switching to ACH therapy (14%). The ACH discontinuation rate was 84% and treatment switching rate was 4%. The mean (standard deviation) time to treatment failure was 143 (130) days for mirabegron and 69 (69) days for ACH. Adherence and persistence patterns were similar in the sensitivity analysis using a ≥ 45‐day supply gap threshold.ConclusionsThis real‐world study demonstrated low adherence and persistence to mirabegron similar to ACH therapies.

Assessment of level of service measures for two-lane intercity highways under heterogeneous traffic conditions

Many researchers have studied the performance of two-lane intercity highways with the help of different measures. In the current study, the performance of such highways under heterogeneous traffic conditions was examined by using several speed and followers related measures. The data were collected from five study sites located in different regions of India. A new methodology was proposed where followers were identified by using a speed difference (between two consecutive vehicles) range of −4 to + 10 km/h and gap threshold value (lower than a particular gap value) of 10 s. By using acceptance curve method, different critical gap values were suggested for each site to identify the followers. Out of all the performance measures, the number of followers as a proportion of capacity (NFPC) and follower density were found to be the best and second best parameters. Finally, different level of service ranges were proposed based on NFPC using cluster analysis.

Car Following Model on Motorway Weaving Sections

This paper focuses on the understanding of the acceleration driving behaviour in motorway weaving sections. An analysis of detailed trajectory data collected from moderately congested traffic flow of a typical weaving section in the M1 motorway, UK (J 42-43). The proposed acceleration model allows the car-following behaviour (acceleration/deceleration) corresponds with both stimulus (positive/negative relative speed). The model is conditional on gap threshold and reaction time distributions (probabilistic model) capturing the heterogeneity across drivers. most of traffic response differently from the stimulus condtions where 43.5% falls in deceleration with positive relative speed. All the parameters in each model are estimated jointly using Maximum Likelihood Estimation technique and reveal significant differences.

Identification of Free Flowing Vehicles on Two Lane Intercity Highways under Heterogeneous Traffic condition

Abstract: A free moving vehicle is a vehicle that travels at their desired speed without any influenced from other vehicles within the same traffic stream or in the opposite traffic stream and the speed is considered as free-flow speed (FFS). This FFS or in another word desired speed can achieve only when the vehicle is travelling in the FFC. FFC is one of the key parameters which is directly related to the LOS assessment for two-lane highways. In the past decades, different researchers used different methodologies to calculate the FFC but all of them were based on homogeneous traffic conditions while in India heterogeneous traffic condition occurred. US HCM 2010 recommend calculating FFS at low traffic volume as vehicle will travel under FFC. On the other hand, other researchers suggested different critical headway value in order to identify the FFC. So, there was a need to examine the previously proposed guidelines or methodology in order to examine their suitability for heterogeneous traffic condition. Different five study sites were selected from different regions of India and different relationships were established between previously used measures to identify the FFC. It was concluded that headway can't be used under heterogeneous traffic condition as well travel mean speed and 85 th percentile speed also. So, a new measure namely; speed difference (SD), which is the difference in speed of two consecutive vehicles in the traffic stream introduced in this study. A relationship was established between SD and headway threshold but it found inappropriate for the existing heterogeneous traffic condition at all the study sites. Finally, the gap is used instead of headway and found suitable for heterogeneous traffic condition. A critical gap threshold value of 10 seconds was observed at all the study sites which showed that the vehicles would be in FFC after that critical gap value and ultimately FFS can be calculated by considering those vehicles which were travelling greater than 10 sec gap value.