Output performance of the novel active transcutaneous bone conduction implant Sentio at different stimulation sites.

Objectives: The output performance of a novel semi-implantable transcutaneous bone conduction device was compared to an established percutaneous bone-anchored hearing system device using cadaver heads. The influence of actuator position, tissue growth below the actuator and mounting it on the surface or in a flattened bone bed on the performance of the implanted actuator was investigated.

Materials And Methods: The percutaneous and the new transcutaneous device were sequentially implanted at two sites in five human cadaver heads: 55 mm superior-posterior to the ear canal opening (position A) and, closer to the cochlea, about 20 mm inferior-posterior to the ear canal opening behind the pinna on the mastoid (position B).

Middle Ear Actuator Performance Determined From Intracochlear Pressure Measurements in a Single Cochlear Scala.

Hypothesis: Intracochlear pressure measurements in one cochlear scala are sufficient as reference to determine the output of an active middle ear implant (AMEI) in terms of "equivalent sound pressure level" (eqSPL).

Background: The performance of AMEIs is commonly calculated from stapes velocities or intracochlear pressure differences (PDiff). However, there are scenarios where measuring stapes velocities or PDiff may not be feasible, for example when access to the stapes or one of the scalae is impractical.

Anatomy of the Human Osseous Spiral Lamina and Cochlear Partition Bridge: Relevance for Cochlear Partition Motion.

The classic view of cochlear partition (CP) motion, generalized to be for all mammals, was derived from basal-turn measurements in laboratory animals. Recently, we reported motion of the human CP in the cochlear base that differs substantially from the classic view. We described a human soft tissue "bridge" (non-existent in the classic view) between the osseous spiral lamina (OSL) and basilar membrane (BM), and showed how OSL and bridge move in response to sound.

Superior Canal Dehiscence Similarly Affects Cochlear Pressures in Temporal Bones and Audiograms in Patients.

Objectives: The diagnosis of superior canal dehiscence (SCD) is challenging and audiograms play an important role in raising clinical suspicion of SCD. The typical audiometric finding in SCD is the combination of increased air conduction (AC) thresholds and decreased bone conduction thresholds at low frequencies. However, this pattern is not always apparent in audiograms of patients with SCD, and some have hearing thresholds that are within the normal reference range despite subjective reports of hearing impairment.

Cochlear partition anatomy and motion in humans differ from the classic view of mammals.

Mammals detect sound through mechanosensitive cells of the cochlear organ of Corti that rest on the basilar membrane (BM). Motions of the BM and organ of Corti have been studied at the cochlear base in various laboratory animals, and the assumption has been that the cochleas of all mammals work similarly. In the classic view, the BM attaches to a stationary osseous spiral lamina (OSL), the tectorial membrane (TM) attaches to the limbus above the stationary OSL, and the BM is the major moving element, with a peak displacement near its center.

Infrasound transmission in the human ear: Implications for acoustic and vestibular responses of the normal and dehiscent inner ear.

The transmission of infrasound within the human ear is not well understood. To investigate infrasound propagation through the middle and inner ear, velocities of the stapes and round window membrane were measured to very low frequencies (down to 0.9 Hz from 2000 Hz) in fresh cadaveric human specimens.

Otoacoustic emission estimates of human basilar membrane impulse response duration and cochlear filter tuning.

This study describes a method based on temporal suppression of click-evoked otoacoustic emissions (CEOAEs) to estimate the time course and duration of human basilar membrane impulse responses (BM IRs). This was achieved by tracing the suppression of dominant peaks in the CEOAE spectrum as a function of the temporal separation between two equal-level stimulus clicks. The relationship between the suppression pattern and underlying BM IR duration near the generation site of the CEOAE frequency was established using model simulations.