Sudden sensorineural hearing loss (SSNHL), a rare audiological condition that accounts for 1% of all cases of sensorineural hearing loss, can cause permanent hearing damage. Soon after the launch of global COVID-19 vaccination campaigns, the World Health Organization released a signal detection about SSNHL cases following administration of various COVID-19 vaccines. Post-marketing studies have been conducted in different countries using either pharmacovigilance or medico-administrative databases to investigate SSNHL as a potential adverse effect of COVID-19 vaccines. Here, we examine the advantages and limitations of each type of post-marketing study available. While pharmacoepidemiological studies highlight the potential association between drug exposure and the event, pharmacovigilance approaches enable causality assessment. The latter objective can only be achieved if an expert evaluation is provided using internationally validated diagnostic criteria. For a rare adverse event such as SSNHL, case information and quantification of hearing loss are mandatory for assessing seriousness, severity, delay onset, differential diagnoses, corrective treatment, recovery, as well as functional sequelae. Appropriate methodology should be adopted depending on whether the target objective is to assess a global or individual risk.

This systematic review examined current literature, summarised research findings and identified research gaps regarding the efficacy of statins on audiological outcomes.
Systematic search of electronic databases and grey literature was performed. Eligibility criteria were the study of a statin drug with report of audiological outcomes such as hearing, tinnitus or balance in either human or animal studies. Data extraction and quality assessment were performed by two independently researchers. The characteristics of the study and research findings were collated and summarised. A narrative synthesis was conducted. Meta-analysis was not possible due to heterogeneity of the included studies.
Analysis of searches yielded 17 studies meeting the criteria. Included studies had variable drug type and dosage, outcome measures and associated inner ear conditions. Most animal experiments showed promising audiological outcomes after statin treatment, demonstrated by the results of auditory brainstem response, distortion product otoacoustic emissions and inner ear histology. However, no clear effect can be discerned in human trials due to the mixed results, and heterogeneity in research methodology and quality. Audiological outcomes were not always correlated with cholesterol levels.
Statins remain a potential candidate as otoprotective agents which warrant further investigation.

Underwater noise, whether of natural or anthropogenic origin, has the ability to interfere with the way in which marine mammals receive acoustic signals (i.e., for communication, social interaction, foraging, navigation, etc.). This phenomenon, termed auditory masking, has been well studied in humans and terrestrial vertebrates (in particular birds), but less so in marine mammals. Anthropogenic underwater noise seems to be increasing in parts of the world\'s oceans and concerns about associated bioacoustic effects, including masking, are growing. In this article, we review our understanding of masking in marine mammals, summarise data on marine mammal hearing as they relate to masking (including audiograms, critical ratios, critical bandwidths, and auditory integration times), discuss masking release processes of receivers (including comodulation masking release and spatial release from masking) and anti-masking strategies of signalers (e.g. Lombard effect), and set a research framework for improved assessment of potential masking in marine mammals.