Central auditory processing involves the neural mechanisms in the brainstem, thalamus, and auditory cortex that interpret acoustic signals from the cochlea. This is where time and level differences are analyzed, patterns are recognized, and speech is understood. Disorders of this processing manifest themselves in symptoms such as poor speech comprehension in noise, despite normal peripheral function. Diagnostic procedures such as evoked potentials (ABR, MLR, CAEP) and dichotic hearing tests examine central processing pathways. Rehabilitation aims to promote neural plasticity through targeted auditory training and cognitive therapy.

The central loudness control regulates the subjective perception of volume in the brain and adapts it to environmental conditions. It integrates information from both ears and prioritizes relevant signals to ensure comfort and protection. Dysfunctions lead to hyperacusis or insufficient compression in hearing aids. Measurements of the discomfort threshold (UCL) and loudness scaling tests provide information about central loudness adjustments. Modern hearing aid models mimic this control through adaptive compression and automatic level adjustment.

The central auditory memory stores acoustic impressions—words, melodies, and sound patterns—for seconds to minutes to enable speech comprehension and music reproduction. It links auditory stimuli with semantic and emotional memory content in the temporal lobe and hippocampus. Impairments, e.g., due to dementia or traumatic brain injury, lead to difficulties in following longer passages of speech. Tests such as the Auditory Continuous Performance Test measure auditory memory span and memory performance. Auditory training and mnemonic strategies can strengthen central auditory memory.

Central nervous hearing loss is caused by lesions in the auditory cortex or brain stem and manifests itself in poor speech comprehension despite normal hearing thresholds. Causes include stroke, multiple sclerosis, or tumors in the central auditory pathways. Audiologically, normal OAE is observed, but delayed evoked potentials and impaired dichotic listening tests. Therapy involves rehabilitation of central processing functions through targeted hearing and speech training. Interdisciplinary care with neurologists and audiologists is crucial.

Cervical reflexes are muscle-neuronal reactions in the neck and shoulder area that are triggered by vestibular stimuli, e.g., during head acceleration. They help to stabilize the head-trunk position and are measured in clinical vestibular diagnostics using EMG recordings. Changes in reflex amplitude or latency indicate peripheral or central vestibular disorders. Tests such as the vestibulospinal reflex (VSR) complement caloric and vHIT tests. Rehabilitation trains cervical reflex pathways to restore head stability.

Room volume refers to typical everyday noise levels indoors, usually between 30 and 50 dB A. It includes quiet conversation, typewriter clicks, or background music. Audiologically, room volume is used as a reference point for hearing aid amplification to ensure comfort in living spaces. Standards recommend not overcompensating hearing aid amplification at these levels to avoid feedback. Measurements in the living environment help to define individual fitting parameters.

Zinc-air batteries are small, high-performance batteries that are widely used in hearing aids. They use oxygen from the air as cathode material, which enables high energy density and long running times. Activation occurs by removing a protective film; decreasing voltage indicates consumption. Disadvantages include limited service life after activation and sensitivity to moisture. Modern hearing aids optimize consumption through energy-saving modes and inform the wearer about the remaining battery life.

Pineal gland volume regulation is a hypothetical, scientifically unproven idea that melatonin rhythms in the pineal gland could influence hearing sensitivity. To date, there are no reliable studies proving a direct link between melatonin levels and hearing thresholds. Instead, research focuses on circadian fluctuations in vestibular functions and hormone balance mechanisms. Clinically relevant are daily hearing fluctuations, which are more likely to be due to pressure and fluid changes in the ear. Therefore, the pineal gland currently plays no role in hearing medicine.

Circular hearing loss is a rare finding in which the audiogram shows concentric drops around a mid-frequency, meaning that both sides of a peak are reduced. It indicates band-shaped damage to the basilar membrane or specific hair cell damage. Causes can include ototoxic substances or certain noise patterns. DPOAE mapping and electrocochleography are used for differential diagnosis. Treatment requires targeted filtering and amplification in the affected frequency band.

Sibilants are high-frequency consonants such as /s/, /ʃ/ and /z/, which are formed by turbulent airflow at the teeth. They have strong energy in the 4–8 kHz range and are particularly susceptible to high-frequency loss. In speech audiometry, sibilant recognition is tested in order to optimize high-frequency amplification in the hearing aid. Misperception of sibilants leads to intelligibility problems, especially in German. Fitting software emphasizes sibilant frequencies to improve discrimination.

Vestibular-related tremors are subtle, involuntary oscillations of the eyes (nystagmus) or head caused by malfunctions in the vestibular system. They occur when signals are processed incorrectly in the semicircular canals or central vestibular nuclei. Clinically, tremors are observed during caloric tests or head impulse tests. Their characteristics (direction, frequency) provide information about the location of the lesion. Vestibular rehabilitation aims to suppress pathological oscillations through adaptation and substitution.

Sensitivity to drafts describes the phenomenon whereby sudden air movements in the ear canal trigger cold stimuli and can cause ear pain or increased tinnitus. It is caused by irritation of exposed nerve endings when there is little earwax protection or perforation. Those affected report sharp pains or pressure fluctuations when windows are opened for ventilation or fans are in operation. It is recommended to protect the ear canal from strong drafts with soft earplugs or hearing protection. In severe cases, an ENT doctor will check the integrity of the eardrum and treat any inflammation.

An auxiliary amplifier is an external device that further amplifies the hearing aid signal, such as an FM receiver or Bluetooth streamer. It increases speech levels in difficult situations such as lectures or the theater by feeding the useful signal directly into the hearing aid. Modern auxiliary amplifiers connect wirelessly and synchronize with the hearing aid's automatic volume control. They extend the dynamic range beyond the internal amplifier circuitry. Audiologists configure auxiliary amplifier profiles according to the listening environment and user needs.

Zygomatic tension refers to the activity of the zygomaticus major muscle during smiling and facial expressions, which runs via facial nerves close to the ear canal. Strong muscle contractions can mechanically narrow the ear canal and cause short-term changes in air conduction audiometry. In tone audiometry, attention is paid to relaxing the facial muscles in order to avoid artifacts. Zygomatic tension can play a role in mimic-induced objective tinnitus (snapping sounds). Clinically, facial expressions are controlled in order to rule out unconscious disruptive factors during hearing tests.