Hearing Research

Aging has profound effects on sensory systems, such that older adults can report problems in hearing despite having normal audiometric thresholds. While it is known that older listeners have poorer temporal processing than younger listeners, there is limited understanding of how these deficits interact with effects of sound level, in particular when they are above conversational level (e.g., > 65 dB SPL). Here we wanted to investigate the link between temporal processing and sound level as a function of age in normal-hearing listeners. Using a forward-masking paradigm, auditory brainstem responses (ABRs) and behavioral detection thresholds were measured at different masker levels. It was found that with increasing age and masker sound level, the Wave V amplitudes of older listeners decreased and directly correlated with behavioral detection thresholds of the probe stimulus in the forward-masking paradigm. These results elucidate the fundamental effects of aging on temporal processing and its interactions with sound level in the central auditory system. The results of this study have clinical implications for the concept of normal hearing in the aging population and how older listeners may struggle in different listening environments that are not captured by simple audiometry. Further delineating the important effects of aging will pave the way for earlier clinical diagnosis of hearing disorders and personalized treatments for different forms of age-related hearing loss.

Standard hearing tests miss cochlear neural degeneration (CND), the loss of synapses between inner hair cells and auditory nerve fibers that may underlie unexplained hearing difficulty in roughly one in ten adults. Envelope following responses (EFRs) can index this neural loss noninvasively, but conventional protocols are too slow for clinical use. We tested a dynamic amplitude-modulated (dAM) EFR that sweeps the full modulation spectrum in a single brief stimulus. In Mongolian gerbils with histologically verified CND, dAM EFRs revealed selective deficits at fast modulation rates without threshold elevation. A machine-learning classifier distinguished young from middle-aged animals with high accuracy; additionally, its most informative feature, power near 400-500 Hz, tracked synapse counts, indicating a readout of cochlear neural health rather than age. Applied without retraining to 56 human listeners, the gerbil-trained classifier separated age groups above chance. dAM EFRs thus offer a rapid, objective and clinically viable marker of CND.

Distinct auditory nerve (AN) fiber populations with varying thresholds and vulnerabilities to synaptopathy are observable in animal models, but standard non-invasive human measures lack the resolution to differentiate these groups of fibers. This fundamental limitation hinders the translation of findings in animals to human auditory pathologies. To overcome this, we developed a novel refractoriness-masking paradigm to non-invasively isolate threshold-specific AN fiber responses in humans. By presenting rapid click trains with cumulatively rising levels (45 to 105 dB peSPL) at a 250-microsecond inter-click interval, we sequentially masked lower-threshold fibers. Using a tympanic membrane electrode, we recorded compound action potentials (CAPs) in adults with normal hearing and isolated threshold-specific responses via waveform subtraction. Our results demonstrated that the isolated CAPs exhibited decreased latencies with increasing levels and a non-linear amplitude growth, plateauing at 90 dB peSPL before sharply increasing at 105 dB peSPL. This pattern reflects the sequential recruitment of AN fiber that were not effectively recruited by the preceding clicks. Validate conditions, in which the final two clicks had equal levels, produced substantially smaller CAPs, consistent with response suppression by refractoriness. Overall, this paradigm establishes a human measurement approach for characterizing level-threshold-dependent AN responses, providing a potential way to better investigate different AN pathologies, such as cochlear synaptopathy or auditory neuropathy.

The pure-tone audiogram remains the cornerstone of hearing assessment, yet it captures only part of the functional consequences of cochlear damage. Most phenotyping schemes rely solely on the audiogram, which cannot detect hidden suprathreshold dysfunction when thresholds are normal. How best to represent audiological data - as discrete phenotypes or as a continuous space - remains unresolved. Using a retrospective database from the Copenhagen Hearing and Balance Centre, Rigshospitalet (Denmark; 1995-2022; 251986 ear-session units from 81883 adults with normal or sensorineural audiograms), we compared linear (PCA) and non-linear (UMAP) embeddings of the audiogram alone and with word recognition in quiet (WRSmax-Q). Here we show that a linear embedding suffices for the audiogram, but a non-linear one becomes advantageous once suprathreshold measures are added. PCA compressed the audiogram onto two interpretable axes, overall level and slope, explaining 91.5% of the variance, with ears forming a continuous cloud that published reference schemes tiled into overlapping regions. For the audiogram alone, UMAP recovered the same organisation. WRSmax-Q varied widely among ears with similar audiograms; adding it left the PCA unchanged but reorganised the UMAP. A synthetic experiment illustrated this: ears with identical audiograms but different WRSmax-Q separated under UMAP, not PCA. Combining thresholds with WRSmax-Q, UMAP yielded a continuous representation - a prototype Hearing Loss Map - where each ear's position reflects threshold and suprathreshold measures. Representing hearing loss as a location in a continuous space rather than as discrete categories may better reflect its graded nature, with clinical relevance for individual patients.

Many individuals experience problems that are undetected by standard hearing tests, such as persistent tinnitus and difficulties understanding speech in background noise. Here, we report evidence of altered neural gain in young adults with self-reported listening problems despite exceptional hearing thresholds. Individuals reporting persistent tinnitus (the daily percept of sound in the absence of an external source) exhibited elevated thresholds of the middle ear muscle reflex, suggestive of altered gain in brainstem reflexive circuits, and reduced cortical responses to auditory spatial cues conveyed in the temporal fine structure of low-frequency sounds. Moreover, in both groups, greater self-reported speech-in-noise difficulties were associated with higher magnitude cortical responses, particularly at the highest stimulus intensity, consistent with elevated neural gain. Using a conceptual model, we demonstrate how damage to high-threshold auditory nerve fibres innervating cochlear nuclei can account for reduced activity of binaural neurons sensitive to the temporal fine structure of low-frequency sounds, generating a compensatory increase in neural gain in higher brain centres that impacts listening in complex environments.

Hearing loss and deafness as a result of hair cell loss cannot be restored due to the incapacity of spontaneous regeneration of these cells. Compounds that manipulate key signaling pathways can potentially regenerate cochlear hair cells. In order to test different compounds that promote hair cell regeneration in vitro models can be used. Three-dimensional cultures have allowed the expansion and experimentation of human and mouse inner ear organoids. This is mainly performed in the embryonic or the early postnatal developmental stage. However, since the majority of patients with hearing loss are adult, it is crucial to understand the adult inner ear regenerative capacity. Here, we evaluated progenitor cell markers in the adult human and mouse inner ear and the generation, expansion and differentiation of cochlear organoids derived from the adult human and mouse inner ear. Cochlear and vestibular sensory epithelium from adult humans; and from adult and aged mice express the progenitor markers SOX2 and LGR5; and can generate organoids in vitro. By optimizing the culture conditions, organoids derived from the cochlea and vestibular organ from adult human and adult and aged mouse differentiated to Myosin 7A positive cells. This indicates that the adult inner ear has regenerative capacity. These findings are encouraging for future regenerative therapies to cure hair cell-related hearing loss and deafness.

Objective: Kabuki syndrome type 2 (KS2) is a rare X-linked disorder caused by pathogenic variants in KDM6A and is frequently associated with hearing impairment. Because auditory phenotypes include sensorineural, conductive, and mixed hearing loss, we examined whether Kdm6a deficiency directly impairs cochlear morphology or auditory function in mice. Methods: We generated Nestin-Cre; Kdm6a conditional mutants and a germline-derived global Kdm6a deletion model using Sox2-Cre-mediated germline recombination. Auditory function and cochlear morphology were assessed by auditory brainstem responses (ABRs), distortion product otoacoustic emissions (DPOAEs), and histological analyses. Results: Whole-body hemizygous or homozygous Kdm6a deletion resulted in embryonic lethality. Analyses therefore focused on Nestin-Cre; Kdm6aflox/Y males and females carrying a germline-derived heterozygous Kdm6a deletion. In Nestin-Cre mutants, ABR thresholds, wave I amplitudes and latencies, and DPOAE measures at 8, 16, and 32 kHz were comparable with littermate controls at 4 and 8 weeks. In heterozygous deletion females, ABR thresholds, wave I amplitudes and latencies at 4-64 kHz and DPOAE measures at 8, 16, and 32 kHz were comparable with male and female wild-type controls. No overt cochlear pathology was observed in either model. Conclusion: Kdm6a deficiency in the viable mouse models examined did not produce overt cochlear pathology or baseline auditory dysfunction. These findings suggest that partial Kdm6a loss alone is insufficient to produce a robust primary cochlear phenotype in young mice and highlight the potential contributions of non-cochlear, developmental, central, and later-onset mechanisms to hearing impairment in KS2. Clinically, these findings support careful evaluation for potentially treatable middle-ear disease.

Bilateral cochlear implantation (BCI) can improve spatial hearing in adults with bilateral hearing loss, but the early development of spatial hearing following sequential BCI remains poorly understood. This prospective longitudinal study investigated changes in spatial hearing experience in 23 adults undergoing sequential BCI, assessed before and at ~1, 3, and 8 months after bilateral implantation under two conditions: spontaneous and restrained head movements. Using a motion-tracking system combined with virtual reality, sound localization was assessed through absolute and signed errors, along with self-reported localization confidence and listening effort. Subjective spatial hearing was also assessed using the Speech, Spatial and Qualities of Hearing Scale (SSQ). Localization performance improved by 1 month after bilateral implantation, as evidenced by a reduction of absolute error and in the bias toward the first-implanted ear. Participants reported greater localization confidence and lower listening effort at 1 month, although these changes were not consistently maintained at later follow-ups. SSQ scores showed improved spatial hearing at 1 month, speech perception at 3 months, and sound clarity and discriminability at 8 months. Compared with head-restrained condition, accuracy and confidence improved when spontaneous head rotations were allowed. The temporal trajectories of localization bias, confidence, and effort were modulated by the duration of experience with the first CI. These findings indicate that changes in spatial hearing can emerge soon after second CI activation. They further highlight the contribution of spontaneous head movements and previous CI experience, and support the use of complementary measures to monitor the early development of bilateral listening.

Metabotropic glutamate receptors (mGluR) are G-protein coupled receptors that regulate neuroplasticity and have been shown to play a role in auditory processing. However, not much is known about the expression of mGluRs during cochlear nucleus development in the context of Fragile X syndrome (FXS). FXS is the most common heritable form of intellectual disability and autism and is associated with auditory processing deficits including hypersensitivity. Audiogenic seizure is a notable feature of the Fmr1 knock-out (KO) mouse model for FXS, in which mGluR5 has been shown to be necessary. In this study, we investigated the expression of eight metabotropic glutamate receptors (mGluRs) in the cochlear nucleus at both young and adult ages and in wildtype and Fmr1 KO mice. While it is established that mGluR1 is the predominantly expressed mGluR in adult cochlear nucleus, we report the following new finding that mGluR5 is the more abundant receptor during early development. The expression of Group II and III mGluRs (2,3,4,6,7,8) was relatively stable during development. We show that mGluR1 and mGluR5 are co-expressed across multiple neuron types. Fmr1 genotype did not have statistically significant impact on the expression pattern of mGluRs in cochlear nucleus. Although hearing onset occurs during this mGluR5 to 1 transition period, mGluR expression patterns were not impacted by cochlear activity. We conclude that there is an mGluR5 is to mGluR1 transition that occurs within cochlear nucleus neurons during the critical period closure that is intrinsic to neuronal development.

The relationship between neural processes supporting perception, deviance processing, and post-perceptual task demands during auditory processing is not well understood. We used multitone masking and a no-report inattentional deafness paradigm to dissociate neural correlates of auditory perceptual awareness, deviance processing, and task demands. Evoked responses to physically identical target-tone pairs were recorded across three phases differing only in task instructions. In Phase A, human participants remained nave to (and thus unaware of) the target tones. In Phase B, participants were informed about (and thus aware of) the target tones. In Phase C, participants remained aware of the target tones and judged the duration of the silent gap between them, rendering them task-relevant. When participants were aware of them, target tones elicited an auditory awareness negativity and an increased positivity in the P3 window), with larger responses when target tones were additionally task-relevant. Furthermore, though largest in Phase C, deviant stimuli elicited a mismatch negativity across all task conditions, while a significant P3 to deviants was only observed in Phase C. Thus, early and late responses can be independently modulated by awareness, deviance, and task-relevance, indicating that they do not necessarily rely on shared neural mechanisms despite overlapping spatiotemporal profiles.

Computational models of the middle ear are typically developed within the linear range of the middle ear's response, which corresponds to typical sounds in daily life. Understanding middle-ear biomechanics under high-intensity sounds is also important for assessing potential auditory damage under adverse conditions. In this study, a finite-element (FE) model of the human middle ear plus the external ear canal is presented, employing a first-order Ogden hyperelastic material formulation and time-domain nonlinear analysis to capture nonlinear deformation of soft tissues and the resulting middle-ear response. The model was analyzed using pure-tone pressure excitations applied at the ear canal entrance over the 80 Hz to 8 kHz frequency range and 110 to 180 dB sound pressure levels (SPL). The ear canal pressure near the tympanic membrane (TM) and full-field three-dimensional response of the middle ear structures were examined. Across the investigated frequency range, the simulated middle-ear motion exhibited a transition from predominantly piston-like behavior at low frequencies, up to 1 kHz, to increasingly intricate multi-modal and multi-directional vibration patterns at higher frequencies. Nonlinear behaviors became increasingly significant at high frequencies and high stimulus levels, including compressive/expansive pressure-displacement relationships, waveform distortions, and the emergence of non-harmonic spectral components. The model developed in this study provides a computational framework for studying nonlinear sound transmission through the middle ear and its implications for high-intensity acoustic exposure. The findings contribute to a better understanding of middle-ear mechanics under adverse conditions and support future investigations of acoustic trauma and hearing protection strategies.

Semi-occluded vocal tract (SOVT) exercises are widely used in voice training and therapy, but their immediate electroglottographic (EGG) effects remain incompletely characterized. In this pilot methodological study, six female community singers completed a no-straw baseline recording and then 1-min straw-phonation exercises with four straws (Household metal, Metal VoiceStraw, plastic, and paper), each followed by a no-straw EGG recording. Thirty 1s recordings were analyzed with a standardized pipeline including contact quotient (CQ), waveform skewness, contact-phase rise/fall timing, temporal skewness (s_t), a normalized derivative asymmetry index (NDAI), average-cycle morphology, and EGG spectral descriptors. Relative to baseline, group-mean CQ was higher after all four straws (by 0.027-0.058), waveform skewness and NDAI were lower, and the EGG spectral centroid was lower (by 9.6-15.3%). Contact-phase timing asymmetry did not change consistently: s_t exceeded baseline after three straws and fell below it after one, and the rise/fall ratio decreased in three to five of six participants depending on the straw. Four participants ranked the Metal VoiceStraw first and two ranked paper first. Because every straw condition followed the baseline, warm-up and order effects cannot be separated from straw effects. These hypothesis-generating results identify CQ, waveform skewness, and EGG spectral centroid as candidate endpoints for a larger controlled study

PurposeDuring speech planning, the brain predicts the auditory consequences of its movements and modulates the auditory system--a process called pre-speech auditory modulation (PSAM). We investigated the link between PSAM and behavioral error correction and determined how aging influences these mechanisms. MethodsSeventeen young adults (18-32 years) and 13 older adults (50-85 years) performed a speaking task involving auditory feedback perturbations and a silent reading control. We measured electrophysiological responses (N1/P2) to auditory probes during speech planning and correlated these modulations with the magnitude of participants subsequent behavioral corrective responses. ResultsBoth groups showed significant modulation of N1 and P2. However, N1 modulation correlated with corrective responses only in young adults. Older adults showed reduced behavioral corrections and smaller, delayed P2 components. Despite these age-related behavioral differences and the loss of the modulation-correction correlation, older adults maintained modulation magnitudes comparable to those of younger adults. ConclusionsN1 modulation serves as a neural index of the brains predictive processes during speech planning. Aging appears to selectively disrupt the integration of these signals into motor output rather than the internal generation of the predictions themselves.

Neural tracking of speech is a well-established phenomenon in neuroscience. However, for speech signals with a fixed structure, significant correlations between speech envelopes and neurophysiological representations occur even for unheard sentences. We exploit a structured speech-in-noise matrix hearing test (Oldenburger Sentence Test, OLSA) to systematically quantify the relationship between acoustic sentence similarity and neural tracking. Simultaneous magnetoencephalography (MEG) and 76-channel electroencephalography (EEG) data, including 16 channels positioned directly around the ears (ear-EEG), were recorded from 21 young adults with normal hearing during the presentation of clean-speech audiobooks and OLSA sentences at six signal-to-noise ratios. A linear decoder trained on audiobooks reconstructed OLSA sentence envelopes. Reconstruction accuracies were compared using a linear mixed model across heard (matched) and unheard (mismatched) sentences of varying acoustic similarity. Significant reconstruction accuracies were achieved across MEG, EEG, and ear-EEG for both matched and mismatched sentences. For mismatched sentences, these accuracies gradually increased with their acoustic similarity to the heard speech data. The high similarity between sentences, which is especially prominent in matrix tests, can cause significant spurious tracking for mismatched stimuli. This effect can reach levels comparable to those of matched sentences and can be mistaken for true neural tracking. Robust neural tracking across modalities further supported the established viability of ear-EEG compared to whole-head systems.

Predicting when an event will occur is key to perceiving and evaluating dynamic sensory inputs, such as speech. The utility of temporal predictions hinges on perceptual timing precision (PTP), the sensitivity to deviations between actual and predicted sound onset times. Past work suggests that PTP is primarily determined by acoustic properties of target sounds, regardless of the acoustics of preceding sound cues. In contrast, in four experiments, we discover that PTP is best when context and target sound spectra and temporal envelopes match, with only minor effects of individual sound acoustics. This ability to utilize contextual continuity improved with musical aptitude. Theoretical modeling showed that spectrally tuned oscillatory entrainment to sound onsets and offsets is necessary to account for our results. In sum, the precision of temporal predictions is defined not by the acoustics of individual sounds but by the continuity of spectral and temporal content within a sound stream.

The vestibular system consists of peripheral end organs that provide the brain with temporally precise information about head position in space required for motor coordination and postural stability. Irregular vestibular afferents of the inner ear are particularly sensitive to rapid changes in acceleration, or jerk, which is necessary for making quick, corrective movements and postural adjustments. Vestibular short-latency evoked potentials (VsEPs) are waveforms that provide a measure of synchronous irregular afferent activity originating from peripheral (early peaks) and central (later peaks) vestibular pathways. These VsEPs are elicited by head jerk stimuli, commonly used preclinically. Previous studies have shown that early VsEP waves are dependent upon jerks of an adequate intensity, number, and duration. However, less is known about jerk characteristics necessary for generation of reliable VsEP signals centrally (later peaks). The present study examines the precise temporal dynamics of peripheral and central vestibular centers across a broad range of mechanical vestibular load in rats. We found differential changes in synchrony and timing driven by jerk repetition, intensity, and duration between early and late VsEP waves representing distinct anatomical components of the vestibular circuit. Our results suggest that central components are uniquely sensitive to jerk duration, intensity, and repetition, indicating a disconnect between peripheral and central neuronal recruitment, adaptive plasticity, and time-frequency dynamics. This work provides a foundation for using VsEP to assess jerk-induced physiological vestibular dysfunction and to understand how central relays differentially adapt to variations of mechanical vestibular stress compared with the precise, high-fidelity transmission observed in the periphery.

Activity in the gamma frequency range (>30Hz) serves as a neural hallmark of stimulus encoding across multiple sensory modalities. Based on its distinct properties, this activity could be classified as broadband or narrowband oscillations. Visual stimuli, such as a grating, induce narrowband oscillations, which have shown promise as diagnostic markers for neurological disorders. However, such tasks are discomforting for the subjects. These can be made subject-friendly by swapping the stimulus for an auditory one; however, most auditory stimuli elicit a broadband activity. In search of an ideal candidate to induce auditory narrowband oscillations, we previously recorded responses to auditory gratings in electroencephalography (EEG) recordings (Gulati & Ray, 2024) using a passive listening paradigm. We observed a focal sustained broadband increase in high gamma activity (70-150Hz), which was not selective towards any stimulus attributes. Nevertheless, since EEG represents activity of a large population, it remained unclear whether observed activity represented a broadband increase or comprised multiple narrowband rhythms, and whether it was indeed untuned. To elucidate this, we recorded invasively from the regions on and around the superior temporal gyrus, closer to Heschl's gyrus of seven patients undergoing epilepsy resection surgery. Patients were either under anesthesia or fully awake while we presented auditory gratings through loudspeakers. We found a transient increase in broadband gamma activity (30-100Hz) followed by a sustained suppression of beta rhythm (14-28Hz). This broadband gamma was selective for slower spectro-temporal modulations. Our result compares the responses obtained across different recording scales and corroborates that auditory gratings produce broadband but not narrowband gamma activity.

Severe hearing impairment affects approximately 5% of the global population, with a prevalence projected to increase over the coming decades. Cochlear implant devices pose a neuroprosthetic treatment option to allow sound perception and speech comprehension. However, users are limited in the spectrum of auditory information they can regain because electrical stimulation of the auditory nerve generates a broad spread of current and limits the transmission of sound frequency information. Recently, optogenetic stimulation of the cochlear nerve has emerged as a promising alternative for hearing restoration. Because light can be precisely confined in space, optogenetic stimulation of the cochlea permits to activate auditory neurons within smaller tonotopic regions, thereby improving the encoding of sound frequencies compared to electrical stimulation. However, this approach is limited in terms of dynamic range and ability to follow rapidly varying inputs, thus preventing faithful transmission of auditory information. Here, we developed an alternative approach targeting directly sensory inner hair cells with optogenetics. We demonstrate that this approach decreases the amount of light energy necessary to evoke auditory responses. Direct stimulation of hair cells increases the dynamic range of intensities encoded by neurons in subcortical auditory areas and improves the temporal fidelity of optogenetic responses. Finally, a biophysical model of the auditory system suggests that preserving the synapses between inner hair cells and auditory neurons greatly improves the encoding performance of an optical cochlear implant. Together, our results suggest that targeting sensory inner hair cells is a promising approach for hearing restoration through an optical implant.

We investigated how auditory and visual presentation of small numerical magnitudes and non- numerical magnitudes are passively processed at the neural level. Earlier research suggests automatic processing of quantities occurs rapidly in the brain. However, there are no studies on passive, pre-attentive change detection of magnitudes utilizing mismatch negativity (MMN) across sensory modalities in same participants, important to understand amodal processing of magnitudes. We recorded EEG in passive auditory and visual multi-feature oddball and control paradigms from the same adult individuals (N=104/105, respectively). In the auditory paradigm, the standard stimulus was a 2-part sound, while the deviant stimuli varied in frequency, intensity, gap length, and number of sounds (1-part and 3-part stimuli). In the visual paradigm, the standard stimulus was a dot array containing two medium-sized dots, while the deviant stimuli varied in numerosity (1 or 3 dots) and dot size (small or large). The results for the auditory paradigm showed significant MMN across all features, including comparisons with deviant-alone control stimuli, except for the 2-part vs. 1-part contrast. The results for the visual paradigm suggested differences in processing across all features apart from large and medium-size stimuli. These results replicate earlier MMN findings that the brain distinguishes pre-attentively changes in sound frequency, amplitude and gap. Auditorily presented small numerical magnitudes also showed pre-attentive processing but less robustly to the contrast 2 vs. 1. Visual pre-attentive processing of small numerical magnitudes was also observed. Together these findings could be interpreted to support the existence of abstract, pre- attentive processing of numerical magnitudes. Highlights* Auditory and visual processing of numerical and non-numerical magnitudes was examined with EEG * Auditory non-numerical magnitudes and medium vs. small dots replicated earlier MMN studies * aMMN and vMMN showed pre-attentive processing of changes in small numerosities 2 vs. 3 and 2 vs. 1 * 2 vs. 1 tone processing was less robust than 2 vs. 3 or the processing of the visual contrasts * The brain processes changes in small non-symbolic magnitudes pre-attentively

Purpose: To compare continuous wavelet transform (CWT) and short-time Fourier transform (STFT) analyses of the oscillatory potentials (OPs) of the dark-adapted full-field electroretinogram (FFERG). Methods: FFERG recordings from Royal College of Surgeons (RCS) and healthy Brown Norway (BN) rats, wild-type and Atoh7 enhancer-knockout (KO) mice, and patients with diabetic retinopathy and healthy controls were analyzed with STFT and with CWT employing the real Morlet wavelet, after 60 Hz high-pass and sharp 60 Hz notch filtering. Time- and frequency-localized OP features were quantified and the methods compared on detection of transient OP signals. Both were additionally validated using synthetic OP-like bursts of known frequency embedded in each cohort's recorded noise. Results: CWT revealed distinct time-frequency patterns and disease-specific OP alterations across all rat, mouse, and human cohorts, with improved temporal localization and frequency resolution, whereas STFT merged transient features and was more susceptible to noise. CWT-derived dominant-frequency differences reached significance in all three models; the corresponding STFT difference reached significance only in rats (separate tests; methods not directly compared). In synthetic bursts, both methods recovered injected frequencies to within 1-2.5 Hz, but only CWT resolved two bursts separated by 15 ms. Conclusions: CWT employing the real Morlet wavelet provides a robust, physiologically relevant evaluation of OPs, with improved temporal localization and reduced spectral dispersion relative to STFT in clinical and experimental settings. Translational Relevance: CWT analysis may improve the characterization of inner retinal dysfunction by preserving transient OP time-frequency structure, as illustrated in preclinical rodent models and diabetic retinopathy patients.