Reverberation refers to the delayed reverberation of sound in a room caused by reflections from walls, ceilings and furnishings. The reverberation time (RT60) is the time it takes for the sound pressure to drop by 60 dB and determines speech intelligibility and sound quality in rooms. Reverberation times that are too long obscure speech signals and make it difficult to understand, while those that are too short create a "dead" sound sensation. In sound reinforcement and room acoustics planning, materials and geometries are selected in such a way that a balanced reverberation behavior is achieved. Hearing aid users benefit from optimized reverberation control as it reduces the load on central speech processing.

Post-amplification is an adaptive amplification measure in hearing aids that reacts to recognized speech signals with a time delay in order to emphasize quiet passages. Unlike real-time compression, it intervenes retrospectively when speech energy is below the comfort threshold. This improves speech intelligibility in dynamic situations without unintentionally amplifying loud impulses. Parameters such as delay time and amplification strength are individually adapted to the hearing profile. Clinical studies show that post-amplification is particularly beneficial for rapid changes in volume.

Proximity hearing loss describes the decrease in hearing ability for soft sounds as the distance to the sound source increases. It is based on the free sound propagation law (distance law), which states that sound pressure decreases by 6 dB per doubling of distance. People with hearing loss are more affected by this effect, as their need for amplification of quieter signals increases. In audiology, proximity hearing loss is used to calibrate hearing aid amplification for different distances. Room acoustic measures and near-field microphones can compensate for the effect.

Near-field communication is a wireless radio technology in the high-frequency range (13.56 MHz) that uses short distances of just a few centimetres. In hearing acoustics, NFC is used to configure hearing aids via smartphone or tablet and to change programs. The technology enables secure pairing without visible cables and saves battery power thanks to short transmission distances. Fitting apps use NFC to transfer real data from audiograms and filter settings. NFC increases user-friendliness and autonomy in hearing aid management.

Nerve fiber delay is the time it takes for an action potential to travel along an afferent auditory pathway from the inner ear to the brainstem. It depends on fibre diameter, myelination and temperature. Delays in the millisecond range are normal and are documented in ABR measurements. Prolonged latencies indicate demyelination, inflammation or tumors along the auditory pathway. Accurate measurement of nerve fiber delay helps to localize lesion sites and monitor treatment progress.

Neural hearing refers to the central processing of acoustic signals in the brain stem and cortex, beyond peripheral hair cell function. It includes functions such as time and level difference evaluation, pattern recognition and speech interpretation. Even with an intact ear, neural hearing can be impaired (e.g. central auditory processing disorder), resulting in a normal audiogram but poor speech comprehension. Test procedures such as dichotic hearing and evoked potentials test neural processing levels. Rehabilitation targets neural plasticity through auditory training and cognitive therapies.

Vestibular neuritis is an inflammatory damage to the vestibular part of the VIIIth cranial nerve. cranial nerve, usually of viral origin. It causes sudden onset of severe rotary vertigo, nausea and gait instability, without primary hearing loss. Vestibular function tests (caloric, VEMP) show ipsilateral deficits. Treatment includes corticosteroids, vestibular rehabilitation and symptomatic concomitant medication. The prognosis is usually favorable, as central compensatory mechanisms restore the balance in the long term.

A neuronoma is a tumorous neoplasm of nerve cells in the brain or nerve tissue, rarely in the auditory system. In the cerebellopontine angle, neurinomas of the VIII. Cranial nerve (acoustic neuroma) can be described as a neuronoma. They compress the auditory and vestibular nerves and lead to unilateral hearing loss, tinnitus and dizziness. Diagnosis is by MRI with contrast medium, treatment by microsurgical resection or stereotactic radiotherapy. Early detection improves preservation of nerve function and quality of life.

Neuroplasticity is the ability of the nervous system to adapt structurally and functionally to changes in stimuli or damage. In the auditory system, it manifests itself after hearing loss or cochlear implantation through the reorganization of cortex areas. Targeted hearing training and rehabilitation promote plastic processes and improve speech comprehension. Imaging procedures (fMRI) can be used to document plastic changes. Plasticity is a basic prerequisite for successful hearing rehabilitation, but decreases with age.

Neurotoxicity refers to the damage to nerve tissue caused by chemical substances, including ototoxins such as aminoglycosides, cisplatin or solvents. In the ear, these substances lead to hair cell damage, synapse loss and neuronal degeneration. Early detection is achieved through otoacoustic emissions and ABR monitoring during therapy. Protective strategies include dose reduction, ototoxicity-protective adjuvants and regular hearing checks. Long-term consequences range from tinnitus to irreversible sensorineural hearing loss.

Non-linear distortion occurs when a system processes sound signals that are not proportional to the input signal, creating harmonics and intermodulation products. In hearing aids, they can impair sound fidelity and speech understanding if amplifier stages or transducers are not working optimally. Distortion factor measurements quantify the degree of non-linear distortion and help in the selection and calibration of hearing systems. Digital signal processors use linear pre-equalization and feedback suppression to minimize distortion. High levels of distortion can also increase neurological processing and promote hearing fatigue.

Noise canceling is an active technology for suppressing ambient noise, in which a microphone picks up the noise signal, inverts it in real time and adds it to the useful signal. The result is that disturbing low-frequency and constant noises - such as aircraft noise or the hum of an air conditioning system - are effectively reduced. In hearing aids and headphones, noise canceling improves speech comprehension in noisy environments and reduces listening effort. Adaptive algorithms continuously adjust the filter settings to changing noise levels. Disadvantages can include a slightly reduced spatial auditory impression and battery consumption.

A noiser is an integrated tinnitus masker in modern hearing aids that emits a quiet noise signal to mask ringing in the ears and promote habituation. The spectrum and volume of the noiser can be individually adjusted to the wearer's tinnitus character. Continuous, pleasant noise eliminates the focus on the tinnitus and reduces cognitive stress. Noiser programs can be activated depending on the situation or automatically controlled by noise detection. Clinical studies have shown that integrated noiser functions significantly improve sleep quality and comfort for tinnitus patients.

The nomenclature of audiological tests includes standardized terms for procedures such as sound, speech, otoacoustic emissions (OAE) and evoked potentials (ABR, CAEP). Standardized terminology facilitates communication between audiologists, ENT specialists and researchers. It clearly defines test parameters such as frequency range, level, masking and stimulus type. International standards (ISO, IEC) and professional societies publish guidelines for correct nomenclature. Consistent naming ensures reproducibility and comparability of test results.

Normal hearing refers to hearing thresholds within the reference limits of 0 to 20 dB HL across the frequency spectrum from 125 Hz to 8 kHz. People with normal hearing reliably perceive speech and everyday sounds without technical aids. Audiometric tests confirm normal hearing through symmetrical air and bone conduction curves without significant threshold deviations. Subtle central auditory processing problems (e.g. hidden hearing loss) can also occur with normal hearing. The term serves as a starting point for the classification of degrees of hearing loss and treatment decisions.

The norm curve in the audiogram is the standardized line that represents the normal hearing threshold across frequencies and serves as a reference for comparison. Deviations of the measured threshold curve from this line indicate the degree and pattern of hearing loss. Norm curves are based on population surveys and reference levels according to ISO and ANSI standards. In the fitting software, the norm curve visualizes target gain profiles for hearing aids. Audiologists use the deviations to determine individual audiogram adjustments and fitting targets.

The standard threshold is the reference level defined in audiology (0 dB HL) for the minimum perceptible sound pressure amplitude under standard conditions. It varies slightly with test frequency, but is internationally standardized to ensure comparability of test results. Values above the standard threshold define the degree of hearing loss. The standard threshold is the basis for the calibration of audiometers and hearing system parameters. It also serves as a reference value in otoacoustic emission tests and evoked potentials.

The cochlear nucleus is the first central connection station of the auditory pathway in the brain stem, where fibers of the vestibulocochlear nerve end. It is divided into ventral and dorsal nucleus complexes, which handle different aspects of acoustic signal processing, such as temporal fine structure and spectral information. From here, neurons continue to the superior olive complex, lateral lemniscus and subsequent auditory centers. Lesions in the cochlear nucleus lead to central auditory processing disorders despite intact peripheral function. Intraoperative evoked potentials (ABR) measure the integrity of the cochlear nucleus and its connections.

The frequency of use of hearing aids describes how often and in which situations wearers use their hearing aids. Optimal use (daily, several hours) correlates strongly with successful fitting, speech comprehension and quality of life. Audiologists record usage patterns using questionnaires, wearing time recording in the device and smart app statistics. Common hurdles are stigma, handling problems and limited comfort. Interventions such as training programmes and individualized adaptations significantly increase user acceptance.

Nystagmus is an involuntary, rhythmic pattern of eye movement, often in response to vestibular stimuli or neuronal lesions. It can be spontaneous, positionally or calorically triggered and can vary in direction and speed. The analysis of nystagmus characteristics (e.g. direction, latency, decay time) provides differentiated information about peripheral and central vestibular pathologies. Video nystagmography (VNG) and Frenzel spectacles are standard diagnostic tools. Therapeutically, vestibular rehabilitation and pharmacological interventions aim to reduce pathological nystagmus patterns.