Presence Of Contralateral Noise Research Articles

NO AFTER-EFFECTS OF COVID-19 INFECTION IN TERMS OF STANDARD AUDIOLOGICAL TESTS

IntroductionCoronavirus disease (COVID-19), considered to be caused by a novel coronavirus (SARS-CoV-2), is an acute respiratory disease which was declared a pandemic by the World Health Organization. Previously published reports have shown contradictory findings on the involvement of the auditory system in individuals infected with COVID-19. The present study aims to assess auditory system functioning in individuals post-COVID-19 infection and compare the results with individuals without COVID-19 infection.Material and methodsParticipants in this study were 30 individuals who had experienced mild COVID-19 infection and 30 individuals who never had COVID-19. Participants were aged between 18 and 40 years. Testing was done 1 to 6 months after infection, and involved conventional and extended high-frequency audiometry, speech perception in quiet and at different signal-to-noise ratios (SPIN), transient evoked otoacoustic emissions (TEOAEs) in quiet and in the presence of contralateral noise, and auditory brainstem response (ABR) in the ipsilateral and contralateral mode.ResultsNone of the tests – pure-tone thresholds, speech perception in quiet and in noise, TEOAE with and without contralateral noise, and ABR – showed any significant difference between individuals who never had COVID-19 infection and those who had recovered from the infection. Both afferent and efferent auditory pathways showed normal findings in individuals post-COVID-19 infection.ConclusionsIndividuals who have been infected with mild COVID-19 did not show any significant deficit in any of the audiological tests, suggesting that the disease does not cause any permanent harm to the auditory system after the infection has subsided.

The role of medial olivocochlear activity in contralateral suppression of auditory steady-state responses

The auditory steady-state response (ASSR) amplitudes fall in the presence of contralateral noise. However, whether and to what extent medial olivocochlear (MOC) activity involves in contralateral suppression of ASSR remain unclear. Therefore, we assess the role of MOC activity in contralateral suppression of ASSR. Mice were treated with strychnine to completely eliminate MOC activity and then measured ASSR amplitudes in the presence of contralateral noise. The contralateral noise reduces ASSR amplitudes at some stimulus intensity. After treating with the strychnine to eliminate MOC activity, ASSR amplitudes recovered again. MOC activity participated in contralateral suppression of ASSR.

Contralateral noise degrades frequency-coding accuracy in normal-hearing adults

Noise presents a constant challenge in daily communication. Previous research has demonstrated the effects of ipsilateral noise on speech processing in the human brain. In this study, we examined the effects of contralateral noise on the accuracy of frequency coding at the subcortical level. Byusing a speech stimulus that mimicked the English vowel /i/ with a rising frequency contour, we obtained scalp-recorded, frequency-following responses in nine normal-hearing adults. To determine the effects of contralateral noise, we performed two experimental conditions: with and without the presence of contralateral noise. Results indicated that the fidelity of frequency coding, as reflected through Tracking Accuracy and Slope Error, were significantly degraded when continuous white noise was added to the contralateral ear. These findings provide important information and help us better understand how frequency cues are processed in noisy environments.

Medial olivary complex reflex in term newborns with hyperbilirubinemia

ObjectiveThis study aimed to compare the integrity of the efferent auditory pathways of newborns that had high hyperbilirubinemia levels and required treatment due to these and healthy newborns. MethodsTerm-born (37 weeks or later) infants that were brought to the Newborn Polyclinic of the Başkent University Hospital were included in the study. The study included a total of 84 infants including healthy newborns (n = 42) and those that had jaundice and were receiving phototherapy (n = 42). After conducting a general otorhinolaryngology examination on all newborns included in the study, Transient Otoacoustic Emission (TEOAE) test was carried out in the absence and presence of contralateral noise. The obtained contralateral suppression values were compared between the two groups. ResultsIn the TEOAE test, the responses obtained at 1 kHz in the newborns receiving phototherapy were found to be lower. The difference between the groups was significant (p = 0.038). The rates of suppression presence at 2 kHz, 2.8 kHz and total OAE were found significantly higher (p < 0.05) in the group not receiving phototherapy. Among the phototherapy-receiving infants, the hyperbilirubinemia levels of the infants in whom suppression was obtained in the contralateral suppression test did not show a statistically significant difference in comparison to those in whom suppression was not obtained (p > 0.05). ConclusionBased on the obtained data, hyperbilirubinemia may have a disruptive effect on the efferent auditory system in newborns. Consequently, we are of the opinion that, in addition to hearing screening in risky newborn infants, a MOC suppression test would be useful.

Medial olivocochlear functioning and speech perception in noise in individuals with polycystic ovary syndrome

Introduction The current study aimed to evaluate the olivocochlear bundle functioning and speech perception in the presence of noise in females with Polycystic ovary syndrome (PCOS). Method Twenty participants in the age range of 18-25 years were included in the study. They were equally divided into two groups: group 1 included females diagnosed with PCOS, and group 2 included healthy adult male participants. Medial olivocochlear (MOC) functioning was evaluated using contralateral suppression of transient otoacoustic emissions (TEOAE). In addition, speech perception in noise was assessed using a quick speech perception in noise test in Malayalam. Results Results showed a significant difference for the TEOAE amplitude and signal to noise ratio (SNR) of TEOAEs in quiet and in the presence of contralateral noise and the speech perception in noise between the two groups. Also, no contralateral suppression was noted in the clinical group suggesting that MOC functioning is affected in individuals with PCOS. Conclusion It can be concluded that medial olivocochlear bundle functioning and speech perception in noise is affected in individuals with PCOS, which can be attributed to the abnormality in the hormonal status of PCOS.

Effect of levodopa on cochlear mechanics and efferent auditory system of Parkinson's disease individuals.

To evaluate the effect of levodopa on cochlear dynamics and on the medial olivocochlear efferent pathway of idiopathic Parkinson's disease (PD) individuals. Individuals with and without PD, followed at a University Hospital, were submitted to Distortion Product Otoacoustic Emissions (DPOAE) and DPOAE Inhibitory Effect (OAEIE) in the presence of contralateral noise. Correlation measures between DPOAE and OAEIE results with Hoehn&Yahr (H&Y) stage, daily dose of levodopa and PD diagnosis period were established. Furthermore, electroacoustic measures were compared between individuals without and those with PD, stratified by dose of levodopa daily administered. Weak negative correlation between DPOAE amplitude and daily dose of levodopa was found, as well positive correlations between EIEOA with daily dose of levodopa and time of PD diagnosis, respectively. Higher DPOAE amplitude was found in individuals with PD using daily doses of levodopa ≤ 600 milligrams when compared to individuals without PD and those with PD using higher doses. EIEOA was lower in individuals using doses ≤ 600 milligrams, when compared to the other groups. Daily doses of levodopa up to 600 mg / day increase the cochlear mechanical-transducer responses in 2 and 3 kHz frequencies, while the action of olivocochlear efferent systems is reduced in this region.

Contralateral Noise Stimulation Delays P300 Latency in School-Aged Children.

Background and ObjectiveThe auditory cortex modulates auditory afferents through the olivocochlear system, which innervates the outer hair cells and the afferent neurons under the inner hair cells in the cochlea. Most of the studies that investigated the efferent activity in humans focused on evaluating the suppression of the otoacoustic emissions by stimulating the contralateral ear with noise, which assesses the activation of the medial olivocochlear bundle. The neurophysiology and the mechanisms involving efferent activity on higher regions of the auditory pathway, however, are still unknown. Also, the lack of studies investigating the effects of noise on human auditory cortex, especially in peadiatric population, points to the need for recording the late auditory potentials in noise conditions. Assessing the auditory efferents in schoolaged children is highly important due to some of its attributed functions such as selective attention and signal detection in noise, which are important abilities related to the development of language and academic skills. For this reason, the aim of the present study was to evaluate the effects of noise on P300 responses of children with normal hearing.MethodsP300 was recorded in 27 children aged from 8 to 14 years with normal hearing in two conditions: with and whitout contralateral white noise stimulation.ResultsP300 latencies were significantly longer at the presence of contralateral noise. No significant changes were observed for the amplitude values.ConclusionContralateral white noise stimulation delayed P300 latency in a group of school-aged children with normal hearing. These results suggest a possible influence of the medial olivocochlear activation on P300 responses under noise condition.

The olivocochlear reflex strength and cochlear sensitivity are independently modulated by auditory cortex microstimulation.

In mammals, efferent projections to the cochlear receptor are constituted by olivocochlear (OC) fibers that originate in the superior olivary complex. Medial and lateral OC neurons make synapses with outer hair cells and with auditory nerve fibers, respectively. In addition to the OC system, there are also descending projections from the auditory cortex that are directed towards the thalamus, inferior colliculus, cochlear nucleus, and superior olivary complex. Olivocochlear function can be assessed by measuring a brainstem reflex mediated by auditory nerve fibers, cochlear nucleus neurons, and OC fibers. Although it is known that the OC reflex is activated by contralateral acoustic stimulation and produces a suppression of cochlear responses, the influence of cortical descending pathways in the OC reflex is largely unknown. Here, we used auditory cortex electrical microstimulation in chinchillas to study a possible cortical modulation of cochlear and auditory nerve responses to tones in the absence and presence of contralateral noise. We found that cortical microstimulation produces two different peripheral modulations: (i) changes in cochlear sensitivity evidenced by amplitude modulation of cochlear microphonics and auditory nerve compound action potentials and (ii) enhancement or suppression of the OC reflex strength as measured by auditory nerve responses, which depended on the intersubject variability of the OC reflex. Moreover, both corticofugal effects were not correlated, suggesting the presence of two functionally different efferent pathways. These results demonstrate that auditory cortex electrical microstimulation independently modulates the OC reflex strength and cochlear sensitivity.

Distortion product otoacoustic emission fine structure is responsible for variability of distortion product otoacoustic emission contralateral suppression

Alteration of the distortion product otoacoustic emission (DPOAE) level by a contralateral sound, which is known as DPOAE contralateral suppression, has been attributed to the feedback mechanism of the medial olivocochlear efferents. However, the limited dynamic range and large intra- and intersubject variabilities in the outcome of the measurement restrict its application in assessing the efferent function. In this study, the 2f(1)-f(2) DPgram was measured with a high frequency resolution in six human ears, which exhibits a fine structure with the quasiperiodic appearance of peaks and dips. In the presence of contralateral noise, the DPOAE level increased, decreased, or remained unchanged depending on the frequency. At the peaks, DPOAEs were mostly suppressed with a larger change, while those at the dips had greater variance, with increased occurrence of enhancement or no change. The difference between the peak and dip frequencies in the DPOAE-level change was significant. A switch from suppression to enhancement of the DPOAE level or vice versa with a small change in frequency was noted. These results imply that the DPOAE fine structure is a main source of the variability in DPOAE contralateral suppression measurement. The study suggests that the DPOAE contralateral suppression test would be improved if it is conducted for frequencies at major peaks of the DPOAE fine structure.

Contralateral suppression of distortion product otoacoustic emissions and the middle-ear muscle reflex in human ears

Distortion product otoacoustic emissions (DPOAEs) were measured in the absence and presence of contralateral noise at five levels—below, equal to, and above the middle-ear muscle (MEM) reflex threshold. The resultant changes in DPOAE level and phase were dependent on stimulus frequency and noise level. Both low-level noise, believed to elicit the medial olivocochlear (MOC) reflex, and high-level noise, thought to activate both MOC and MEM reflexes, significantly decreased the DPOAE level. However, the shift from sole MOC effect to mixed MOC and MEM effects was not as dramatic as we thought. While low-level noise resulted in a minimum DPOAE phase change, high-level noise caused a substantial phase lead for 1 and 2 kHz. With increasing frequency, phase lag became more notable. The present study suggests the following: (1) DPOAE contralateral suppression by low-level sound most likely does not involve the effect of the MEM reflex and signal crossover; and (2) combined analysis of DPOAE level and phase changes warrants further investigations to overcome the difficulty in separating the effects of MOC efferents and MEM contraction. The results also imply that OAE measurement has the potential for being used to investigate the effect of the MEM reflex on sound transmission.

Medial olivocochlear bundle activation and perceived auditory intensity in humans

In order to test the hypothesis of a role of cochlear efferent activity in intensity perception in humans, loudness functions, loudness integration, and loudness summation were measured in the absence and in the presence of contralateral noise in normal-hearing subjects. Additionally, relationships with the effect of the noise on evoked otoacoustic emissions (EOAEs) were tested, and comparisons with vestibular neurotomy patients were performed. Overall, the results failed to demonstrate significant effects of contralateral noise stimulation on loudness functions and loudness integration. Furthermore, no significant differences were found in vestibular neurotomy patients. A significant effect of contralateral noise on loudness summation was noted, but was not related to the effect on otoacoustic emissions. The present results fail to support the notion that efferent influences onto the cochlear compression have a significant perceptual effect.

Effects of narrow-band contralateral noise on absolute thresholds in the Japanese macaque

Detection thresholds for pure-tone stimuli were measured in quiet and in the presence of octave-band noise presented simultaneously to the contralateral ear in a group of Japanese macaques. Subjects were trained to respond to the presence of 1-s sinusoids presented to the ipsilateral ear in a go/no-go procedure. All stimuli were presented through insert earphones. Pure-tone stimuli were 1-s in duration and ranged from 125 Hz to 16.0 kHz. Continuous noise stimuli were octave bands, centered at the ipsilateral test-tone frequency, presented at levels of 0 to 70 dB above threshold for the center frequency stimulus. While some variability was evident across subjects, both in the frequency distribution and magnitude (as a function of contralateral noise level) of threshold increases, all subjects exhibited an orderly increase in thresholds in the presence of contralateral noise. Maximum increases in threshold were evident between 1.0 and 4.0 kHz. Measurable threshold elevations were evident at noise levels as low as 20 dB above threshold and, in general, increased systematically with contralateral noise levels. Decreases in threshold were evident at low-noise levels. The characteristics of the measured threshold shifts are similar to efferent suppression effects which have been reported in the physiological literature. [Work supported by NIH.]

Reaction-Time Measures of Ear Advantage in Dichotic Listening

Experiments employing a dichotic listening test to study hemispheric specialization for speech have typically used probability of recall as the response measure to assess ear asymmetry. Reaction-time (RT) measures can be shown to provide additional information about the underlying processes and to reveal asymmetries not found with the traditional paradigm. In the first experiment, subjects monitored a dichotic consonant-vowel (CV) tape for each occurrence of a designated syllable. Whenever that item occurred, subjects manually depressed a button. For right-ear responses, percent correct was higher and reaction times were shorter, with no significant interaction of ear and hand-used-to-respond for either response measure. A second study showed that manual and verbal RT responses to targets produced identical ear differences, suggesting that at least the terminal portion of the processing of each speech input takes place in the left hemisphere. That RT may be a more sensitive tool to study ear asymmetries is suggested by a third study in which manual RT responses were obtained to CV syllables in the presence of contralateral noise. Right-ear RT responses averaged 14 msec shorter than left-ear responses, although percent correct scores did not reveal any asymmetry.

The masking noise and its effect upon the human cortical evoked potential.

Using both while noise and narrow-band noise as monaural stimuli, the human cortical evoked potential was recorded with different intensties of stimuli. With such stimuli, the N1 peak of the response was prolonged in comparison to the response to the onset of a pure tone.The effect of simultaneously stimulating one ear with a burst of pure tone and the other with noise such as might be used for masking the contralateral ear was also studied. In this situation the N1 peak in response to the tone usually showed the amplitude that was to be expected if only the pure tone had been given without contralateral masking. The response to pure tones of various intensity levels in the presence of contralateral noise at a steady intensity was also measured.