What is ‘Normal’ Hearing?
Ask an audiologist what “normal” hearing is and, not surprisingly, you will get a variety of responses (Figure 1). Certainly, normal pure-tone threshold sensitivity does not rule out hearing difficulty or the presence of auditory pathology, including cochlear and auditory neural peripheral or central deficits. Further, a number of non-auditory factors can contribute to a patient’s perceived hearing difficulty (e.g., cognitive capacity, attention, medications, etc.).
Topic(s): Hearing Loss, Normal Hearing, audiology, Audiometry
Audiologists are regularly faced with the patient who presents to their office with a variety of hearing complaints. They often report significant difficulty hearing, particularly in background noise. These hearing difficulties negatively affect them both occupationally and socially. However, upon assessment, the pure-tone audiogram results demonstrate “normal” peripheral hearing sensitivity. These are perhaps not the anticipated results, given the patient’s reported difficulties.
Topic(s): auditory system, central auditory processing (CAP), Central auditory processing disorder (CAPD), brain, Normal Hearing
Hidden hearing loss (HHL) is a popular topic referring to complaints of hearing difficulty or perceived hearing loss despite having “normal” audiometric thresholds. Within the scientific literature, this term has most recently been used to refer specifically to the reduced amplitude of sound-evoked neural responses that occurs with loss of synapses that connect the inner hair cells (IHCs) to the auditory nerve. In other words, the patient’s audiometric difficulties are hidden behind a normal audiogram.
Topic(s): Normal Hearing, perceived hearing complaint, Hidden Hearing Loss (HHL), audiometric threshold, Audiometric Test, inner hair cell (IHC), pure-tone average (PTA), extended high frequencies (EHF), Central auditory processing disorder (CAPD), Auditory Neuropathy Spectrum Disorder ANSD, Tinnitus, hearing handicap inventory for the elderly (HHIE), hearing handicap inventory for the adults (HHIA), noise-induced synaptopathy, auditory brainstem response (ABR), temporary threshold shift (TTS), synaptopathy, speech-in-noise testing (QuickSIN), word-in-noise test, otoacoustic emissions (OAEs), tympanometry and middle-ear muscle reflexes (MEMR), dichotic processing, temporal processing, monaural low-redundancy, binaural interaction, spatial processing, Distortion product otoacoustic emissions (DPOAE), Transient Evoked Otoacoustic Emissions (TEOAE), Auditory Evoked Response