Pediatric acoustics is the specialist discipline that deals with acoustic treatment and hearing aid fitting for children. It takes into account age-specific features such as ear canal anatomy, growing ear molds and the child's hearing loss profile. Diagnostic procedures are designed in a playful way, such as child-friendly audiometry or otoacoustic emissions as screening tools. Hearing aid programs are preset for children before fine adjustments are made in everyday life. Close cooperation with teachers, parents and early intervention specialists ensures optimal speech development and participation in social life.

Pediatric audiology covers the diagnosis, treatment and care of hearing disorders in infants, children and adolescents. It relies on objective test procedures such as OAE screening and AEP measurements, as infants often do not respond reliably to standard audiometry. From pre-school age, playful hearing tests are used to determine hearing thresholds and speech comprehension in an age-appropriate manner. Pediatric audiologists fit hearing systems, accompany speech and language therapy and monitor developmental milestones. An interdisciplinary team including ENT doctors, speech therapists and teachers ensures holistic support.

The papilla spiralis, also known as the organ of Corti, sits on the basilar membrane in the cochlea and is the actual organ of sound perception. It consists of inner and outer hair cells, supporting cells and a gelatinous membrane above the stereocilia. Sound-induced traveling waves in the basilar membrane bend the stereocilia, causing mechano-electrical transduction. The inner hair cell encodes sound information, while the outer hair cells act as active amplifiers. Damage to the spiral papilla leads to sensorineural hearing loss and impaired frequency resolution.

In partial tone audiometry, the hearing threshold is determined using continuous tones that the patient signals by pressing a button. Unlike with impulse audiometry, the tester gradually scans through different frequencies and levels in order to draw a precise threshold curve. The procedure is suitable for detailed diagnostics, for example in cases of suspected cochlear non-linearities or hidden hearing loss. It records adaptation and fatigue effects of the auditory system. Modern audiometers support automated partial tone protocols for consistent results.

A pathological hearing threshold is present if the determined hearing threshold per frequency deviates from the normal values by more than 20 dB HL in the long term. It indicates the presence of hearing loss and determines the degree (mild, moderate, profound). Pathological thresholds can develop gradually (age, noise) or acutely (acoustic trauma, sudden hearing loss). Differentiation between conductive and sensorineural loss is made by comparing air and bone conduction thresholds. Follow-ups show progression or therapy effects and guide treatment decisions.

The tympanic cavity (cavitas tympani) is the air-filled space of the middle ear that surrounds the eardrum, ossicular chain and oval and round windows. It connects to the nasopharynx via the Eustachian tube and serves to equalize pressure. Pathologies such as effusion formation (otitis media with effusion) lead to increased pressure and sound conduction disorders. Tympanometry measures the compliance of the tympanic cavity and provides information on the ventilation status and middle ear pressure. Surgical approaches are often made via the posterior auditory canal for direct intervention in the tympanic cavity.

Tympanostomy tubes are small plastic or metal tubes that are anchored in the eardrum to ensure permanent ventilation of the tympanic cavity. They are indicated in cases of recurrent otitis media, tube dysfunction or risk of cholesteatoma. They enable pressure equalization, secretion drainage and reduce middle ear infections. They are inserted on an outpatient basis under local anesthesia and tubes usually fall out spontaneously after 6-12 months. Control ensures eardrum closure and restoration of hearing function.

Auditory perception encompasses all processes from sound reception to conscious interpretation in the brain. It includes detection, discrimination, recognition and localization of sound sources. Psychophysical methods measure perception by means of threshold and discrimination tests, while neurophysiological methods record evoked potentials. Auditory perception disorders can be present despite normal peripheral function (e.g. central auditory processing disorder). Auditory training and cognitive interventions aim to rehabilitate perceptual abilities.

Perilymph is the sodium-rich fluid in the scala vestibuli and scala tympani of the cochlea, which conducts mechanical vibrations in the cochlea and enables pressure equalization. It surrounds the membranous channels with the endolymph and forms an electrochemical insulation. Injury to the basilar membrane can cause perilymphatic fistula, which leads to vertigo and hearing loss. Perilymph pressure fluctuations are recorded indirectly during electrocochleography. Research is investigating perilymph biomarkers as indicators of hearing loss.

Peritubalitis is an inflammation of the tissue around the Eustachian tube, often as a result of chronic rhinopharyngitis or tubal catarrh. It leads to edema formation, tube stenosis and middle ear pressure effusions. Patients complain of a feeling of pressure, hearing loss and recurrent otitis media. Diagnosis is based on tube function tests, endoscopic inspection and tympanometry. Treatment includes anti-inflammatory nasal drops, tube dilatation and, if necessary, tympanostomy tubes.

Perceptive hearing loss (sensorineural hearing loss) is caused by damage to the hair cells in the cochlea or the auditory nerve fibers. It is shown on the audiogram by equally high air and bone conduction thresholds and cannot be corrected surgically. Causes include noise trauma, ageing processes, genetic defects or ototoxins. Those affected complain of reduced speech comprehension, especially in noisy environments, and benefit from hearing aids or cochlear implants. Rehabilitation measures also include hearing training to strengthen central processing mechanisms.

Whistling in the ear is a form of tinnitus in which those affected perceive a high-frequency, tonal noise. It can occur on one or both sides and fluctuates in volume and frequency. Causes range from noise damage to otosclerosis and central auditory pathway changes. Diagnostics include distortion factor audiometry, OAE and tinnitus screening to determine frequency and level. Therapeutic approaches include sound enrichment with noisers, cognitive behavioral therapy and, if indicated, medication.

The pharyngotympanic tube connects the middle ear with the nasopharynx and enables pressure equalization and ventilation. It opens when swallowing or yawning and otherwise prevents the backflow of secretions into the middle ear. Dysfunctions lead to tubal catarrh, middle ear effusion and hearing loss. Functional tests such as tubal function testing and tympanometry assess their opening ability. Balloon dilatation and tympanostomy tubes are used therapeutically to prevent long-term complications.

The phonatory reflex refers to the involuntary adjustment of voice volume and pitch to the perceived volume of one's own voice. When speaking in a loud environment, you automatically increase the volume (Lombard effect) to ensure speech intelligibility. This reflex is controlled by auditory feedback loops in the brain. In the case of hearing loss, the phonatory reflex is disturbed, resulting in altered voice level and articulation. Speech therapy training can retrain the reflex function and improve speech intelligibility.

A phoneme is the smallest unit of sound in a language that distinguishes meaning, e.g. /p/ vs. /b/ in German. Phonemes are encoded in the auditory system as specific frequency and time patterns and retrieved in the linguistic lexicon. In audiometry and speech therapy, phoneme tests are used to assess articulation and perception skills. Hearing aid programs often emphasize phoneme-relevant frequency bands in order to optimize speech comprehension. Misperception of individual phonemes is typical in cases of high tone loss or central processing disorders.

Phonosurgery comprises microsurgical procedures on the ear that are intended to alleviate hearing function or tinnitus, such as stapedotomy, myringoplasty or implant placement. The aim is to reconstruct the ossicular chain, eardrum or direct auditory nerve stimulation. The focus is on precision and preservation of residual hearing, often supported by intraoperative monitoring. Postoperative audiometry and tympanometry document the success of the procedure. Innovations such as endoscopic techniques reduce tissue trauma and rehabilitation time.

Phonotypy refers to individual physiological requirements and motor patterns of sound production, i.e. how speakers articulate phonemes. It includes lip, tongue and jaw movements as well as the shape of the glottis. With hearing loss, phonotypy often changes unconsciously, leading to unclear pronunciation. Speech therapy analyzes phonotypy and specifically trains articulation patterns. Video and biofeedback improve awareness of phonetic processes.

The pinna is the visible auricle made of elastic cartilage that captures sound waves and conducts them into the ear via the auditory canal. Its complex folding creates frequency-dependent filter effects that contribute to the localization of sound sources in the vertical plane. Variations in the shape of the pinna lead to individual HRTFs and influence spatial hearing. In hearing aid fitting, the pinna adaptation of the earmold must be taken into account to ensure comfort and sound fidelity. Reconstructive surgery (otoplasty) corrects malformations or injuries to the pinna.

The plateau phenomenon in tinnitus refers to a phase in which the pitch and volume of the ringing in the ears remain stable over a period of time before fluctuating again. This stability provides diagnostic certainty during tinnitus screenings and facilitates sound therapy settings. Plateau phases vary in duration from minutes to hours and can be interrupted by stress or noise. Therapeutically, plateaus are used to precisely adjust noise profiles and promote habituation. Documentation of plateau duration helps to monitor tinnitus progression.

The brachial plexus is a nerve plexus consisting of the cervical spinal nerves C5-Th1 and innervates the shoulder and arm. Although it is anatomically located outside the ear area, the accessorius nerve (XI cranial nerve) can be manipulated close to the brachial plexus during surgery in the mastoid or cerebellopontine angle. Injuries lead to weakness of the shoulder lift and pain, which can indirectly promote postural changes and tension in the neck-jaw-ear area. Interdisciplinary planning in otoneurosurgery minimizes plexus damage. Postoperative physiotherapy ensures functional preservation and pain reduction.

The padding of an earmold is usually made of soft silicone or foam and ensures an optimal fit in the ear canal. It absorbs mechanical pressure peaks, prevents pressure points and increases wearing comfort during prolonged listening. At the same time, the padding influences the acoustic seal and therefore the freedom from feedback and frequency response of the hearing system. Different degrees of hardness and material thicknesses allow individual adaptation to the ear anatomy and hearing loss profile. Regular replacement prevents material fatigue and hygiene-related sound changes.

The postauricular muscles (anterior, superior and posterior auricularis muscles) are tiny, often rudimentary muscles around the pinna. In some people, they can move the ear minimally and thus slightly influence the position of the earmold. Their contraction does not usually play a significant role in hearing, but can be observed during certain reflexes and mimic movements. In rare cases, spasms of these muscles lead to objective tinnitus ("pulsating click"). EMG measurements of these muscles can reveal muscular causes of tinnitus.

The potential distribution in electrocochleography (ECochG) describes the amplitudes and latencies of cochlear and nerve potentials along the scala tympani. The sum potential (SP) and action potential (AP) are measured with a needle electrode on the eardrum or ear canal electrode. The SP/AP ratio serves as an indicator of endolymphatic hydrops in Meniere's disease. In addition, the distribution of potentials over different stimulation levels shows the functional reserve of the hair cells. ECochG potential patterns help to differentiate between cochlear and retrocochlear pathologies.

The pre-canalicular form refers to a variant of the pinna in which the entrance to the ear canal is particularly narrow or barely covered by the concha. This anatomy can make the insertion of ITE hearing aids more difficult and increases the risk of cerumen congestion in the cartilaginous canal. When taking impressions, the impression material must be carefully placed in and removed from this area to ensure complete earmolds. Audiologists often choose open earmold designs for pre-canalicular form to optimize ventilation and freedom from feedback. Surgical corrections are only indicated in exceptional cases with functional problems.

The prevalence of hearing impairment indicates the proportion of people affected in a defined population and varies according to age, noise exposure and region. According to the WHO, around 5% of the global population suffer from hearing loss that requires treatment, and this figure rises to over 30% for people over 65. In industrialized countries, age-related hearing loss (presbycusis) is the most common cause, while infectious causes are more common in developing regions. Prevalence studies form the basis for health planning, care provision and prevention programs. Long-term data show an increase in age- and noise-induced hearing disorders due to demographic change and environmental factors.

Presbycusis is an age-related sensorineural hearing loss that typically begins with a decrease in high-frequency hearing loss. Causes include degeneration of hair cells, synaptic deterioration and reduced microvascular perfusion of the cochlea. Symptoms include poor speech understanding in noise, reduced loudness perception and tinnitus. Treatment involves hearing aids with high-frequency amplification and central auditory training to promote neuronal plasticity. Prevention through noise protection and avoidance of ototoxicity can delay the onset.

Pseudohyperacusis refers to an apparent hypersensitivity to sound in which measurements show normal comfort thresholds but patients experience loud sounds as painful. It is psychogenic or caused by attention and anxiety disorders and is not due to peripheral damage. Objective tests (OAE, AEP) are crucial in the differential diagnosis to rule out true hyperacusis. Treatment includes education, cognitive behavioural therapy and gradual desensitization with controlled sound exposure. Interdisciplinary care by audiologists and psychologists improves the prognosis.

Psychophysical methods determine relationships between physical stimulus parameters (level, frequency) and subjective perception (loudness, pitch, masking). Standard methods are threshold determination (hearing threshold), loudness scaling and difference threshold measurement (JND tests). Adaptive methods dynamically adapt stimuli to test subject responses and optimize measurement duration and accuracy. They are the basis for norm curves, hearing aid calibration and psychoacoustic modeling. Validity depends on subject attention, test environment and stimulus protocol.

Psychoacoustics is the science of the perception of sound by the human ear and brain. It investigates phenomena such as loudness perception, masking, pitch resolution and spatial hearing. Psychoacoustic findings are used in the development of hearing aids, audio compression (MP3) and room acoustic design. Methodologically, it combines physical measurements, behavioral studies and neuronal modeling. Fields of application range from hearing diagnostics and sound design to tinnitus and hyperacusis therapy.