For example, a hearing loss of 30 dB would make conversational speech sound more like a whisper. Causes
Only 10 to 15 percent of the cases diagnosed as SSHL have an identifiable cause. Most cases are classified as idiopathic, also called sudden idiopathic hearing loss (SIHL) and idiopathic sudden sensorineural hearing loss (ISSHL or ISSNHL) The majority of evidence points to some type of inflammation in the inner ear as the most common cause of SSNHL. Viral – The swelling may be due to a virus. A herpes type virus is believed to be the most common cause of sudden sensorineural hearing loss. The herpes virus lies dormant in our bodies and reactivates for an unknown reason. Vascular ischemia of the inner ear or cranial nerve VIII (CN8)
Perilymph fistula, usually due to a rupture of the round or oval windows and the leakage of perilymph. The patient will usually also experience vertigo or imbalance. A history of trauma is usually present and changes to hearing or vertigo occur with alteration in intracranial pressure such as with straining; lifting, blowing etc. Autoimmune – can be due to an autoimmune illness such as systemic lupus erythematosus, granulomatosis with polyangiitis

Treatment
Hearing loss completely recovers in around 35-39% of patients with SSNHL, usually within one to two weeks from onset. Eighty-five percent of those who receive treatment from an otolaryngologist (sometimes called an ENT surgeon) will recover some of their hearing.
They will perceive sounds differently, yet the audiogram suggests that they have the same degree of loss. Huss and Moore investigated how hearing impaired patients perceive pure tones, and found that they perceive tones as noisy and distorted, more (on average) than a person without a hearing impairment. However, they also found that the perception of tones as being like noise, was not directly related to frequencies within the dead regions, and was therefore not an indicator of a dead region. This therefore suggests that audiograms, and their poor representation of dead regions, are inaccurate predictors of a patients perception of pure tone quality.Research by Kluk and Moore  has shown that dead regions may also affect the patients perception of frequencies beyond the dead regions. There is an enhancement in the ability to distinguish between tones that differ very slightly in frequency, in regions just beyond the dead regions compared to tones further away. An explanation for this may be that cortical re-mapping has occurred. Whereby, neurons which would normally be stimulated by the dead region, have been reassigned to respond to functioning areas near it. This leads to an over-representation of these areas, resulting in an increased perceptual sensitivity to small frequency differences in tones. Vestibulocochlear nerve pathology
congenital deformity of the internal auditory canal,
neoplastic and pseudo-neoplastic lesions, with special detailed emphasis on schwannoma of the eighth cranial nerve (acoustic neuroma),
non-neoplastic Internal Auditory Canal/CerebelloPontine Angle pathology, including vascular loops,

Diagnosis
Case history
Before examination, a case history provides guidance about the context of the hearing loss.