Background and ObjectivesStrength of medial olivocochlear reflex can be measured reliably using contralateral inhibition of distortion product otoacoustic emissions (DPOAEs) when its fine structure is considered. However, measurement of fine structure of DPOAE is difficult with clinical equipment. Thus, this study investigated the clinically relevant test-retest reliability of contralateral inhibition of DPOAEs.Subjects and MethodsTwenty-six young adults with normal hearing sensitivity participated. DPOAEs were recorded at 27 discrete f2 frequencies between 800 Hz and 8,000 Hz at frequency resolution of 8 points per octave with and without contralateral white noise presented at 50 dB SPL. To check for short term inter-session reliability, contralateral inhibition of DPOAEs were recorded in three sessions, two recording sessions on first day separated by 30 minutes and third time after one week of the first session. Within each session, DPOAEs were recorded twice in single probe-fit condition to test for intra-session reliability.ResultsCronbach’s alpha was calculated having poor reliability (α≤ 0.7) of contralateral inhibition of DPOAEs in both intra-session and inter-session conditions for most of the tested frequencies. 95% confidence intervals of contralateral inhibition magnitude also showed large variability.ConclusionsThe current results showed that though DPOAE amplitudes were highly reliable across sessions, amount of inhibition of DPOAEs was not reliable when DPOAEs were measured at discrete frequencies. These findings are concurrent with the literature.

The present study investigated the ability of native listeners to identify subtle phonetic contrasts in nonsense words and its relationship with the contralateral inhibition of transient evoked otoacoustic emissions (TEOAE). A group of 45 young adults with normal hearing sensitivity who were native speakers of Malayalam participated in the behavioral experiment. Phone identification score and reaction time for four phonetic pairs in nonsense words were measured for each participant. Based on the phone identification score, the participants were divided into high and low performers. Twelve participants randomly selected from each group were evaluated for contralateral inhibition of TEOAEs. Phone identification score and global contralateral inhibition amplitude of TEOAE were significantly higher and reaction time was significantly shorter in high performers than that of low performers. Significant correlation was found between the phone identification score and contralateral inhibition of TEOAE. Strength of the medial olivocochlear bundle activity explained about 30% of the variance in the phone identification scores providing evidence for the involvement of the descending auditory pathways in identifying the phonetic contrasts that are acoustically similar. These results support the emerging view that top down influences from higher centers shapes the responses of lower centers.

Background and ObjectivesP300 has been studied with a variety of stimuli. However, the nature of P300 has not been investigated for deviant stimuli which change its characteristics from standard stimuli after a period of time from onset.Subjects and MethodsNine young adults with normal hearing participated in the study. The P300 was elicited using an oddball paradigm, the probability of standard and deviant stimuli was 80% and 20% respectively. Six stimuli were used to elicit P300, it included two pure-tones (1,000 Hz and 2,000 Hz) and four tone-complexes (tones with frequency changes). Among these stimuli, 1,000 Hz tone served as standard while others served as deviant stimuli. The P300 was recorded in five separate blocks, with one of the deviant stimuli as target in each block. Electroencephalographic was recorded from electrode sites Fz, Cz, C3, C4, and Pz. Latency and amplitude of components of the cortical auditory evoked potentials were measured at Cz.ResultsWaveforms obtained in the present study shows that, all the deviant stimuli elicited obligatory P1-N1-P2 for stimulus onset. 2,000 Hz deviant tone elicited P300 at a latency of 300 ms. While, tone-complexes elicited acoustic change complex (ACC) for frequency changes and finally elicited P300 at a latency of 600 ms. In addition, the results showed shorter latency and larger amplitude ACC and P300 for rising tone-complexes compared to falling tone-complexes.ConclusionsTone-complexes elicited distinct waveforms compared to 2,000 Hz deviant tone. Rising tone-complexes which had an increase in frequency elicited shorter latency and larger amplitude responses, which could be attributed to perceptual bias for frequency changes.

ObjectiveTo identify the effect of dyslipidemia on auditory function detected by Pure Tone Audiometry. To check if dyslipidemia worsens the hearing level in diabetics.DesignThis was a comparative study where 120 subjects between the age group of 20 and 50 years underwent pure tone audiometry, lipid profile and blood sugars. Group 1 consisted of 30 subjects with type 2 diabetes and dyslipidemia; Group 2 had 30 subjects with isolated diabetes; Group 3 had 30 with isolated dyslipidemia and Group 4 included 30 normal subjects as control.ResultsSignificant hearing loss was seen only in the group with isolated diabetes (63%). The most common type of hearing loss was high frequency sensorineural hearing loss. When comparison was made between the combinations of different lipid profiles, no association was found to the level of hearing.ConclusionsDiabetics are more prone to high frequency hearing loss. Altered lipid profile has no role in causing hearing loss.

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Purpose:The study was aimed to investigate the relationship between parental stress and attitude of parents towards the outcomes of cochlear implantation in an Indian scenario. Methods: A total of 59 parents of children with cochlear implantation participated in the study. The outcomes of cochlear implant was measured using Parental attitudes of various aspects of cochlear implantation questionnaire and parental stress was measured using parental stress scale. The questionnaires were circulated to participants and data was collected in the form of e-survey. Results: The present study showed that the parental stress level was similar among mothers and fathers. Further, the parental attitude towards communication abilities of children and education were positively correlated with the duration of cochlear implantation. Finally, a significant positive correlation was found between the parental stress and the parental attitude towards communication abilities of children and social skills. Conclusion: The present study showed a positive relationship between parental stress and parental attitude towards the outcomes of cochlear implantation for aspects of communication abilities and social skills.

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Objectives: Large individual variability is documented for identification performance of native phones, especially in challenging situations. It is not known whether the ability to utilize cues available for phone identification is facilitated by cognitive abilities, thereby explaining a proportion of the individual variability. This study investigated the relationship between working memory capacity and identification of a few Malayalam phones in the absence of contextual cues among native listeners. Methods: Forty native listeners of Malayalam, aged between 18 and 25, participated in this study. Participants identified 8 Malayalam phones embedded in nonsense words. Working memory capacity was measured using tasks such as reading span, operation span, digit forward span, and digit backward span. Identification score for each phone, total phone identification score (average identification score from 8 phones), and reaction time during identification were obtained. Results: Phone identification score of participants ranged from 57.8% to 99%. Pearson product moment correlation analysis showed a significant positive correlation between all measures of working memory capacity and total phone identification score, indicating that working memory capacity play a role in the identification of phones. Reaction time showed a significant negative correlation with digit backward span and operation span. The measures of working memory capacity accounted for 24.7% of the variability in phone identification score. Conclusion: Identification of phones in the absence of contextual cues increases the cognitive load. Therefore, higher working memory capacity might aid in native phone identification in difficult situations. This study reveals the top down influence of cognition on native speech perception.