Central auditory processing comprises the neuronal mechanisms in the brain stem, thalamus and auditory cortex that interpret acoustic signals from the cochlea. This is where time and level differences, pattern recognition and speech comprehension are analyzed. Despite normal peripheral function, disorders of this processing are reflected in symptoms such as poor speech comprehension in noise. Diagnostic procedures such as evoked potentials (ABR, MLR, CAEP) and dichotic hearing tests examine central processing pathways. Rehabilitation aims to promote neuronal plasticity through targeted auditory training and cognitive therapy.

The central loudness control regulates the subjective perception of loudness 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 systems. 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 speech passages. Tests such as the Auditory Continuous Performance Test measure auditory memory span and memory performance. Auditory training and mnemonic strategies can strengthen the 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 central auditory pathways. Audiologically, OAEs are normal, but evoked potentials are delayed and dichotic hearing tests are impaired. Therapy includes 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. when the head is accelerated. They help to stabilize head-torso 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. Rehabilitation trains cervical reflex pathways to restore head stability.

Room volume refers to typical everyday indoor noise levels, 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 rooms. Standards recommend not overcompensating for 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 the cathode material, which enables high energy density and long runtimes. They are activated by removing a peel-off foil; decreasing voltage indicates consumption. Disadvantages are limited service life after activation and sensitivity to moisture. Modern hearing aids optimize consumption through energy-saving modes and inform the wearer of the remaining running time.

Pineal gland sound regulation is a hypothetical, unsubstantiated idea that melatonin rhythms in the pineal gland could influence hearing sensitivity. So far, there are no confirmed studies that prove a direct link between melatonin levels and hearing thresholds. Instead, research focuses on circadian fluctuations of vestibular functions and hormonal balance mechanisms. Clinically relevant are diurnal 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 reductions around a center frequency, i.e. both sides of a peak are reduced. It indicates band-shaped damage on the basilar membrane or specific hair cell damage. Causes may be ototoxic agents 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 air flow on the tooth row. 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 hearing aids. Misperception of sibilants leads to intelligibility problems, especially in German. Fitting software emphasizes sibilant frequencies to improve discrimination.

Vestibular-induced tremors are fine, involuntary oscillations of the eyes (nystagmus) or head, triggered by malfunctions in the vestibular system. They are caused by incorrect signal processing 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.

Draught sensitivity describes the phenomenon that sudden air movements in the ear canal can trigger cold stimuli and provoke earache or tinnitus amplification. It is caused by irritation of exposed nerve endings with thin cerumen protection or perforation. Those affected report stabbing pain or pressure fluctuations when ventilating through windows or using a fan. It is recommended to protect the ear canal from strong draughts with a soft plug or hearing protection. In severe cases, the ENT specialist clarifies the integrity of the eardrum and treats inflammation.

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

Zygomaticus tension refers to the activity of the zygomaticus major muscle during smiles and facial expressions, which run via facial nerves close to the auditory canal. Strong muscle contractions can mechanically constrict the ear canal and cause short-term changes in air conduction audiometry. In tonal audiometry, attention is paid to relaxation of the facial muscles in order to avoid artifacts. Zygomaticus tension can play a role in mimic-induced objective tinnitus (snapping sounds). Clinically, facial expressions are checked to rule out unconscious interfering factors in hearing tests.