Thymoquinone ameliorates age-related hearing loss in C57BL/6J mice by modulating Sirt1 activity and Bak1 expression.

Age-related hearing loss (AHL) is the most common sensory disorder of aged population. Currently, one of the most important sources of experimental medicine for AHL is medicinal plants. This study performed the first investigation of the effect of thymoquinone (TQ), a potent antioxidant, on AHL. Here, we used inbred C57BL/6J mice (B6 mice) as a successful experimental model of the early onset of AHL. The behavioral assessment of hearing revealed that the injection of a high dose of TQ (40 mg/kg; TQ40) significantly improved the auditory sensitivity of B6 mice at all tested frequencies (8, 16 and 22 kHz). Histological sections of cochlea from B6 mice injected with a low dose (20 mg/kg; TQ20) and high dose showed relatively less degenerative signs in the modiolus, hair cells and spiral ligaments, the main constituents of the cochlea. In addition, TQ40 completely restored the normal pattern of hair cells in B6 mice, as shown in scanning electron micrographs. Our data indicated that TQ20 and TQ40 reduced levels of Bak1-mediated apoptosis in the cochlea of B6 mice. Interestingly, the level of Sirt1, a positive regulator of autophagy, was significantly increased in B6 mice administered TQ40. In conclusion, TQ relieves the symptoms of AHL by downregulating Bak1 and activating Sirt1 in the cochlea of B6 mice.

The possibility of cochlear synaptopathy in young people using a personal listening device.

OBJECTIVE: To evaluate the association of listening to music loudly through personal listening devices with cochlear synaptopathy in young adults. METHODS: Fifty healthy young adults selected among 109 volunteers were included in the study. Participants of high risk (n=25) and low risk (n=25) groups estimated according to ETDNL (estimated total daily noise level) were evaluated using pure tone audiometry, tympanometry, matrix test, electrocochleography (EcochG) and auditory brainstem response (ABR) to evaluate the occurrence of cochlear synaptopathy. RESULTS: Audiometric thresholds between the groups were not significantly different (p>0.05). High risk group participants showed poorer performance than the low-risk group on the TurMatrix test, in non-adaptive noise with -5 SNR and -7.5 SNR, and at the 50% understanding SNR level with headphones (p<0.01). There was no difference in the adaptive free field in noise test at which 50% understanding was achieved (p>0.05). The AP amplitudes on EcochG and wave V amplitudes on ABR were significantly smaller in the high-risk group (p<0.05). There was no association between ETDNL and I/V ratio on ABR. CONCLUSION: Poorer performance in TurMatrix and other electrophysiologic tests revealed the negative effect of personal listening devices on the auditory system. Our findings support the hypothesis that personal listening devices could cause cochlear synaptopathy. Long-term studies are needed to determine the effects of binaural hearing and duration of noise exposure on the auditory system.

Noise: Acoustic Trauma to the Inner Ear.

Cochlear damage is often thought to result in hearing thresholds shift, whether permanent or temporary. The report of tinnitus in the absence of any clear deficit in cochlear function was believed to indicate that hearing loss and tinnitus, while comorbid, could arise independently from each other. In all likelihood, tinnitus that is not of central nervous system origin is associated with hearing loss. As a correlate, although a treatment of most forms of tinnitus will likely emerge in the years to come, curing tinnitus will first require curing hearing loss.

The ongoing search for cochlear synaptopathy in humans: Masked thresholds for brief tones in Threshold Equalizing Noise.

This study aimed to advance towards a clinical diagnostic method for detection of cochlear synaptopathy with the hypothesis that synaptopathy should be manifested in elevated masked thresholds for brief tones. This hypothesis was tested in tinnitus sufferers, as they are thought to have some degree of synaptopathy. Near-normal-hearing tinnitus sufferers and their matched controls were asked to detect pure tones with durations of 5, 10, 100, and 200 ms presented in low- and high-level Threshold Equalizing Noise. In addition, lifetime noise exposure was estimated for all participants. Contrary to the hypothesis, there was no significant difference in masked thresholds for brief tones between tinnitus sufferers and their matched controls. Masked thresholds were also not related to lifetime noise exposure. There are two possible explanations of the results: 1) the participants in our study did not have cochlear synaptopathy, or 2) synaptopathy does not lead to elevated masked thresholds for brief tones. This study adds a new approach to the growing list of behavioral methods that attempted to detect potential signs of cochlear synaptopathy in humans.

Electrode estimation in the acoustic region of the human Cochlea.

Background: In this study, a method to estimate number of electrodes in the acoustic region of Electric Acoustic Stimulation (EAS) subjects was proposed. Aims/Objectives: To develop and validate an anatomy-based method for EAS subjects to estimate the number of electrodes within the acoustic region.Material and methods: The postoperative CTs of adults with various degree of hearing implanted with lateral wall electrodes with mean insertion depth of 23.9 mm (18.0-28.2 mm) and mean insertion angle of 505° (355-695°) were evaluated.Results: The difference between the estimated and measured angle varied between -18 and 25°, with a mean of 0.9°. For the insertion angle of 230° and higher, the maximum difference was 24°. Taking this uncertainty into account, all electrodes in the acoustic region were predicted correctly.Conclusions and significance: The method decides on non-overlapping acoustic and electric stimulation in terms of place in the cochlea. With the accuracy of 0.84 mm for the electrode arrays inserted for more than 230°, the method was sufficient to estimate the exact number of electrodes in the acoustic region of cochlear implantees. The benefit of this method may be in fitting of EAS subjects with some portion of the electrode array in the acoustic region.

Formant frequency discrimination with a fine structure sound coding strategy for cochlear implants.

Recent sound coding strategies for cochlear implants (CI) have focused on the transmission of temporal fine structure to the CI recipient. To date, knowledge about the effects of fine structure coding in electrical hearing is poorly charactarized. The aim of this study was to examine whether the presence of temporal fine structure coding affects how the CI recipient perceives sound. This was done by comparing two sound coding strategies with different temporal fine structure coverage in a longitudinal cross-over setting. The more recent FS4 coding strategy provides fine structure coding on typically four apical stimulation channels compared to FSP with usually one or two fine structure channels. 34 adult CI patients with a minimum CI experience of one year were included. All subjects were fitted according to clinical routine and used both coding strategies for three months in a randomized sequence. Formant frequency discrimination thresholds (FFDT) were measured to assess the ability to resolve timbre information. Further outcome measures included a monosyllables test in quiet and the speech reception threshold of an adaptive matrix sentence test in noise (Oldenburger sentence test). In addition, the subjective sound quality was assessed using visual analogue scales and a sound quality questionnaire after each three months period. The extended fine structure range of FS4 yields FFDT similar to FSP for formants occurring in the frequency range only covered by FS4. There is a significant interaction (p = 0.048) between the extent of fine structure coverage in FSP and the improvement in FFDT in favour of FS4 for these stimuli. FS4 Speech perception in noise and quiet was similar with both coding strategies. Sound quality was rated heterogeneously showing that both strategies represent valuable options for CI fitting to allow for best possible individual optimization.

Narrow-band ripple glide direction discrimination and its relationship to frequency selectivity estimated using psychophysical tuning curves.

The highest spectral ripple density at which the discrimination of ripple glide direction was possible (STRtdir task) was assessed for one-octave wide (narrowband) stimuli with center frequencies of 500, 1000, 2000, and 4000 Hz and for a broadband stimulus. A pink noise lowpass filtered at the lower edge frequency of the rippled-noise stimuli was used to mask possible combination ripples. The relationship between thresholds measured using the STRtdir task and estimates of the sharpness of tuning (Q10) derived from fast psychophysical tuning curves was assessed for subjects with normal hearing (NH) and cochlear hearing loss (CHL). The STRtdir thresholds for the narrowband stimuli were highly correlated with Q10 values for the same center frequency, supporting the idea that STRtdir thresholds for the narrowband stimuli provide a good measure of frequency resolution. Both the STRtdir thresholds and the Q10 values were lower (worse) for the subjects with CHL than for the subjects with NH. For both the NH and CHL subjects, mean STRtdir thresholds for the broadband stimulus were not significantly higher (better) than for the narrowband stimuli, suggesting little or no ability to combine information across center frequencies.

Forward masking patterns by low and high-rate stimulation in cochlear implant users: Differences in masking effectiveness and spread of neural excitation.

The goal of the present study was to compare forward masking patterns by stimulation of low and high rates in cochlear implant users. Postlingually deafened Cochlear Nucleus® device users participated in the study. In experiment 1, two maskers of different rates (250 and 1000 pulses per second) were set at levels that produced equal masking for a probe presented at the same electrode as the maskers. This aligned the two masking functions at the on-site probe location. Then their forward masking patterns for the far probes were compared. Results showed that slope of the masked probe-threshold decay as a function of probe-masker separation was steeper for the high-rate than the low-rate masker. A linear model indicated that this difference in spread of neural excitation (SOE) was accounted for by two factors that were not correlated with each other. One factor was that the low-rate masker required a considerably higher current level to be equally effective in masking as the high-rate masker. The second factor was the effect of stimulation rate on loudness, i.e., integration of multiple pulses. This was consistent with our hypothesis that if an increase in stimulation rate does not result in an increased total neural response, then it is unlikely that the change in rate would change spatial distribution of the neural activity. Interestingly, the difference in masking effectiveness of the maskers predicted subjects' speech recognition. Poorer performers were those who showed more comparable masking effects by maskers of different rates. The difference in the masking effectiveness may indirectly measure the auditory neurons' excitability, which predicts speech recognition. In experiment 2, SOE of the high-rate and low-rate maskers were compared at a level that is clinically relevant, i.e., equal loudness. At equal loudness, high-rate stimulation not only produced an overall greater amount of forward masking, but also a shallower decay of masking with probe-masker separation (wider SOE), compared to low rate. The difference in SOE was the opposite to the findings from experiment 1. Whether the maskers were calibrated for equal masking or loudness, the absolute current level was always higher for the low-rate masker, which suggests that the SOE patterns cannot be explained by current spread alone. The fact that high-rate stimulation produced greater masking and wider SOE at equal loudness may explain why using high stimulation rates has not produced consistent benefits for speech recognition, and why lowering stimulation rate from the manufacturer's default sometimes results in improved speech recognition for subjects.

Thermal Effects of Acupuncture by the Infrared Thermography Test in Patients With Tinnitus.

Previous studies have confirmed the efficacy of acupuncture treatment for tinnitus. However, no relevant studies of the exact mechanism of acupuncture efficacy on tinnitus have been published. Enrolled participants with left-sided tinnitus received acupuncture treatment at TE3 and TE5. The acupuncture session lasted for 30 minutes. The infrared thermography (IRT) test of each participant's bilateral aural regions and visual analog scale scores were taken before and after the first acupuncture treatment session. Fifty-four participants accepted acupuncture treatment and the IRT test. The temperature differentials of both sides were reduced significantly, but the maximum, minimum, and average temperature of bilateral aural regions did not have a significant difference before and after acupuncture session. The acupuncture's effects for tinnitus were associated with the improvement of cochlear blood flow via the IRT test. We have planned a full-scale randomized controlled trial to find out more about the underlying mechanisms of acupuncture for tinnitus.

Effect on vestibular function of cochlear implantation by partial deafness treatment-electro acoustic stimulation (PDT-EAS).

PURPOSE: Although the cochlear implantation procedure does not interfere with vestibular structures directly, both the vestibulum and the cochlea share the same inner ear fluid space, and this fluid may be responsible for transferring possibly damaging forces from one to the other. The purpose of the study is to assess postoperative vestibular function after partial deafness treatment-electro-acoustic stimulation (PDT-EAS) cochlear implantation. METHODS: Fifty-five patients were included in the study (30 females, 25 males, age 11-80, mean 41.8 ± 19.35). cVEMP and oVEMP were performed preoperatively and 1-3 months after cochlear implantation. Caloric and vHIT tests were conducted preoperatively and 4-6 months after cochlear implantation. RESULTS: Our study shows that, based on a wide range of electrodes, use of PDT-EAS is protective in terms of preserving vestibular function. It gives a rate of saccular damage of 15.79%, utricular damage of 19.04%, and a horizontal semicircular canal response reduction of 15.79%. CONCLUSIONS: PDT-EAS is protective in terms of preserving vestibular function. Nevertheless, it should be emphasized that the risk of vestibular damage cannot be totally eliminated even when hearing preservation techniques are adopted.

Circadian integration of inflammation and glucocorticoid actions: Implications for the cochlea.

Auditory function has been shown to be influenced by the circadian system. Increasing evidence point towards the regulation of inflammation and glucocorticoid actions by circadian rhythms in the cochlea. Yet, how these three systems (circadian, immune and endocrine) converge to control auditory function remains to be established. Here we review the knowledge on immune and glucocorticoid actions, and how they interact with the circadian and the auditory system, with a particular emphasis on cochlear responses to noise trauma. We propose a multimodal approach to understand the mechanisms of noise-induced hearing loss by integrating the circadian, immune and endocrine systems into the bearings of the cochlea. Considering the well-established positive impact of chronotherapeutic approaches in the treatment of cardiovascular, asthma and cancer, an increased knowledge on the mechanisms where circadian, immune and glucocorticoids meet in the cochlea may improve current treatments against hearing disorders.

Residual inhibition: From the putative mechanisms to potential tinnitus treatment.

Neurons in various sensory systems show some level of spontaneous firing in the absence of sensory stimuli. In the auditory system spontaneous firing has been shown at all levels of the auditory pathway from spiral ganglion neurons in the cochlea to neurons of the auditory cortex. This internal "noise" is normal for the system and it does not interfere with our ability to perceive silence or analyze sound. However, this internal noise can be elevated under pathological conditions, leading to the perception of a phantom sound known as tinnitus. The efforts of many research groups, including our own, led to the development of a mechanistic understanding of this process: After cochlear insult the input to the central auditory system becomes markedly reduced. As a result, the neural activity in the central auditory system is enhanced to compensate for this reduced input. Such hyperactivity is hypothesized to be interpreted by the brain as a presence of sound. This implies that suppression of hyperactivity should reduce/eliminate tinnitus. This review explores research from our laboratory devoted to identifying the mechanism underlying residual inhibition of tinnitus, a brief suppression of tinnitus following a sound stimulus. The key mechanisms that govern neural suppression of spontaneous activity in animals closely resemble clinical psychoacoustic findings of residual inhibition (RI) observed in tinnitus patients. This suppression is mediated by metabotropic glutamate receptors (mGluRs). Lastly, drugs targeting mGluRs suppress spontaneous activity in auditory neurons and reduce/eliminate behavioral signs of tinnitus in mice. Thus, these drugs are therapeutically relevant for tinnitus suppression in humans.

Enhanced Central Neural Gain Compensates Acoustic Trauma-induced Cochlear Impairment, but Unlikely Correlates with Tinnitus and Hyperacusis.

For successful future therapeutic strategies for tinnitus and hyperacusis, a subcategorization of both conditions on the basis of differentiated neural correlates would be of invaluable advantage. In the present study, we used our refined operant conditioning animal model to divide equally noise-exposed rats into groups with either tinnitus or hyperacusis, with neither condition, or with both conditions co-occurring simultaneously. Using click stimulus and noise burst-evoked Auditory Brainstem Responses (ABR) and Distortion Product Otoacoustic Emissions, no hearing threshold difference was observed between any of the groups. However, animals with neither tinnitus nor hyperacusis responded to noise trauma with shortened ABR wave I and IV latencies and elevated central neuronal gain (increased ABR wave IV/I amplitude ratio), which was previously assumed in most of the literature to be a neural correlate for tinnitus. In contrast, animals with tinnitus had reduced neural response gain and delayed ABR wave I and IV latencies, while animals with hyperacusis showed none of these changes. Preliminary studies, aimed at establishing comparable non-invasive objective tools for identifying tinnitus in humans and animals, confirmed reduced central gain and delayed response latency in human and animals. Moreover, the first ever resting state functional Magnetic Resonance Imaging (rs-fMRI) analyses comparing humans and rats with and without tinnitus showed reduced rs-fMRI activities in the auditory cortex in both patients and animals with tinnitus. These findings encourage further efforts to establish non-invasive diagnostic tools that can be used in humans and animals alike and give hope for differentiated classification of tinnitus and hyperacusis.

An improved method of obtaining electrocochleography recordings from Nucleus Hybrid cochlear implant users.

Interest in electrocochleography (ECoG) has recently resurged as a potential tool to assess peripheral auditory function in cochlear implant (CI) users. ECoG recordings can be evoked using acoustic stimulation and recorded from an extra- or intra-cochlear electrode in CI users. Recordings reflect contributions from cochlear hair cells and the auditory nerve. We recently demonstrated the feasibility of using Custom Sound EP (clinically available software) to record ECoG responses in Nucleus Hybrid CI users with preserved acoustic hearing in the implanted ear (Abbas et al, 2017). While successful, the recording procedures were time intensive, limiting clinical applications. The current report describes how we improved data collection efficiency by writing custom software using Python programming language. The software interfaced with Nucleus Implant Communicator (NIC) routines to record responses from an intracochlear electrode. ECoG responses were recorded in eight CI users with preserved acoustic hearing using Custom Sound EP and the Python-based software. Responses were similar across both recording systems, but the recording time decreased significantly using the Python-based software. Seven additional CI users underwent repeated testing using the Python-based software and showed high test-retest reliability. The improved efficiency and high reliability increases the likelihood of translating intracochlear ECoG to clinical practice.

Is There a Safe Level for Recording Vestibular Evoked Myogenic Potential? Evidence From Cochlear and Hearing Function Tests.

OBJECTIVE: There is a growing concern among the scientific community about the possible detrimental effects of signal levels used for eliciting vestibular evoked myogenic potentials (VEMPs) on hearing. A few recent studies showed temporary reduction in amplitude of otoacoustic emissions (OAE) after VEMP administration. Nonetheless, these studies used higher stimulus levels (133 and 130 dB peak equivalent sound pressure level [pe SPL]) than the ones often used (120 to 125 dB pe SPL) for clinical recording of VEMP. Therefore, it is not known whether these lower levels also have similar detrimental impact on hearing function. Hence, the present study aimed at investigating the effect of 500 Hz tone burst presented at 125 dB pe SPL on hearing functions. DESIGN: True experimental design, with an experimental and a control group, was used in this study. The study included 60 individuals with normal auditory and vestibular system. Of them, 30 underwent unilateral VEMP recording (group I) while the remaining 30 did not undergo VEMP testing (group II). Selection of participants to the groups was random. Pre- and post-VEMP assessments included pure-tone audiometry (250 to 16,000 Hz), distortion product OAE, and subjective symptoms. To simulate the time taken for VEMP testing in group I, participants in group II underwent these tests twice with a gap of 15 minutes. RESULTS: No participant experienced any subjective symptom after VEMP testing. There was no significant interear and intergroup difference in pure-tone thresholds and distortion product OAE amplitude before and after VEMP recording (p > 0.05). Furthermore, the response rate of cervical VEMP was 100% at stimulus intensity of 125 dB pe SPL. CONCLUSIONS: Use of 500 Hz tone burst at 125 dB pe SPL does not cause any temporary or permanent changes in cochlear function and hearing, yet produces 100% response rate of cervical VEMP in normal-hearing young adults. Therefore, 125 dB pe SPL of 500 Hz tone burst is recommended as safe level for obtaining cervical VEMP without significantly losing out on its response rate, at least in normal-hearing young adults.

Current Focusing to Reduce Channel Interaction for Distant Electrodes in Cochlear Implant Programs.

Speech understanding abilities are highly variable among cochlear implant (CI) listeners. Poor electrode-neuron interfaces (ENIs) caused by sparse neural survival or distant electrode placement may lead to increased channel interaction and reduced speech perception. Currently, it is not possible to directly measure neural survival in CI listeners; therefore, obtaining information about electrode position is an alternative approach to assessing ENIs. This information can be estimated with computerized tomography (CT) imaging; however, postoperative CT imaging is not often available. A reliable method to assess channel interaction, such as the psychophysical tuning curve (PTC), offers an alternative way to identify poor ENIs. This study aimed to determine (a) the within-subject relationship between CT-estimated electrode distance and PTC bandwidths, and (b) whether using focused stimulation on channels with suspected poor ENI improves vowel identification and sentence recognition. In 13 CI listeners, CT estimates of electrode-to-modiolus distance and PTCs bandwidths were measured for all available electrodes. Two test programs were created, wherein a subset of electrodes used focused stimulation based on (a) broad PTC bandwidth (Tuning) and (b) far electrode-to-modiolus distance (Distance). Two control programs were also created: (a) Those channels not focused in the Distance program (Inverse-Control), and (b) an all-channel monopolar program (Monopolar-Control). Across subjects, scores on the Distance and Tuning programs were significantly higher than the Inverse-Control program, and similar to the Monopolar-Control program. Subjective ratings were similar for all programs. These findings suggest that focusing channels suspected to have a high degree of channel interaction result in quite different outcomes, acutely.

Cortical auditory evoked potentials in cochlear implant listeners via single electrode stimulation in relation to speech perception.

The objectives of this study were to investigate the effects of place of stimulation on cortical auditory evoked potentials in relation to speech performance in cochlear implant listeners. It was designed that cortical responses were recorded for single-electrode bursts at apical, medial and basal portions of the electrode array with varying inter-stimulus intervals ranging from 300 ms to 5 s. Latency and amplitude of N1 and P2 peaks were analysed in relation to monosyllabic word scores. The study sample was 44 adult cochlear implant users ranging in age from 28 to 86 years. N1, P2 and N1-P2 amplitudes declined significantly from apical to basal electrodes. The most robust and pronounced responses were recorded for slower stimulation rates (5 s). Speech recognition correlated positively with N1 and N1-P2 amplitudes at the medial electrode. P2 latency showed a significant negative correlation with speech performance at the apical electrode. At last, cortical responses varied significantly depending on the stimulation site and rate. We can objectively quantify speech performance with the N1, N1-P2 amplitude and P2 latency in cochlear implant users. Deafness-related neural degeneration persists even after the cochlear implantation and is more distinct at the base than the apex of the cochlea.

Chronotolerance for cisplatin ototoxicity in the rat.

Cisplatin is a potent chemotherapeutic compound for which ototoxicity is a significant side effect. Cisplatin has shown sensitivity to circadian time, in that cisplatin is most effective as an anti-tumor compound, and least nephrotoxic, when given in the active (dark) period of the light-dark cycle in rodents. The objective of the study was to determine the sensitivity of cisplatin ototoxicity to circadian time. Fifty-seven Fischer 344/NHsd rats were exposed to 12 mg/kg cisplatin by intra-peritoneal injection at one of six time points on a 12 h light-12 h dark cycle: 2, 6, or 10 h after light onset or 2, 6, or 10 h after light offset. Cochlear injury was evaluated using auditory brainstem response threshold shifts and postmortem outer hair cell counts. All animals experienced threshold shift in the highest frequencies tested (30 and 40 kHz). The animals exposed to cisplatin at 6 h after light onset (the inactive period) had significantly higher mid-frequency threshold shifts and outer hair cell losses than the groups exposed during the dark hours. The results indicate that cisplatin is less likely to cause ototoxicity in the Fischer 344/NHsd rat when given during the active period. This finding is consistent with the lower nephrotoxicity that has been detected in cisplatin-exposed animals treated during the dark hours, and the magnitude of differences in threshold shifts between the light and dark exposure indicates that circadian timing has a significant impact on susceptibility to cisplatin ototoxicity.

In Vivo Electrocochleography in Hybrid Cochlear Implant Users Implicates TMPRSS3 in Spiral Ganglion Function.

Cochlear implantation, a surgical method to bypass cochlear hair cells and directly stimulate the spiral ganglion, is the standard treatment for severe-to-profound hearing loss. Changes in cochlear implant electrode array design and surgical approach now allow for preservation of acoustic hearing in the implanted ear. Electrocochleography (ECochG) was performed in eight hearing preservation subjects to assess hair cell and neural function and elucidate underlying genetic hearing loss. Three subjects had pathogenic variants in TMPRSS3 and five had pathogenic variants in genes known to affect the cochlear sensory partition. The mechanism by which variants in TMPRSS3 cause genetic hearing loss is unknown. We used a 500-Hz tone burst to record ECochG responses from an intracochlear electrode. Responses consist of a cochlear microphonic (hair cell) and an auditory nerve neurophonic. Cochlear microphonics did not differ between groups. Auditory nerve neurophonics were smaller, on average, in subjects with TMPRSS3 deafness. Results of this proof-of-concept study provide evidence that pathogenic variants in TMPRSS3 may impact function of the spiral ganglion. While ECochG as a clinical and research tool has been around for decades, this study illustrates a new application of ECochG in the study of genetic hearing and deafness in vivo.

A Computational Model of Thalamocortical Dysrhythmia in People With Tinnitus.

Tinnitus is a problem that affects a diverse range of people. One common trait amongst people with tinnitus is the presence of hearing loss, which is apparent in over 90% of the cohort. It is postulated that the remainder of people with tinnitus have hidden hearing loss in the form of cochlear synaptopathy. The loss of hearing sensation is thought to cause a reduction in the bottom-up excitatory signals of the auditory pathway leading to a change in the frequency of thalamocortical oscillations known as thalamocortical dysrhythmia (TCD). The downward shift in oscillatory behavior, characteristic of TCD, has been recorded experimentally but the underlying mechanisms responsible for TCD in tinnitus subjects cannot be directly observed. This paper investigates these underlying mechanisms by creating a biologically faithful model of the auditory periphery and thalamocortical network, called the central auditory processing (CAP) model. The proposed model replicates tinnitus related activity in the presence of hearing loss and hidden hearing loss in the form of cochlear synaptopathy. The results of this paper show that, both the bottom-up and top-down changes are required in the auditory system for tinnitus related hyperactivity to coexist with TCD, contrary to the theoretical model for TCD. The CAP model provides a novel modeling approach to account for tinnitus related activity with and without hearing loss. Moreover, the results provide additional clarity to the understanding of TCD and tinnitus and provide direction for future approaches to treating tinnitus.