A mystery solved: human high-frequency middle-ear motion.

The middle ear transforms sound from low-impedance external air to high-impedance cochlear fluid. However, the human stapes - the input to the cochlea - has been reported to have minimal or no motion above ~ 4 kHz. For decades, this lack of observed high-frequency stapes motion has been puzzling, as it is inconsistent with our ability to hear up to 20 kHz.

The impact of size on middle-ear sound transmission in elephants, the largest terrestrial mammal.

Elephants have a unique auditory system that is larger than any other terrestrial mammal. To quantify the impact of larger middle ear (ME) structures, we measured 3D ossicular motion and ME sound transmission in cadaveric temporal bones from both African and Asian elephants in response to air-conducted (AC) tonal pressure stimuli presented in the ear canal (PEC). Results were compared to similar measurements in humans.

Pediatric capacity crisis: A framework and strategies to prepare for a pediatric surge.

A pediatric capacity crisis developed across the country in the Fall and Winter of 2022 due to a combination of factors, including a surge in respiratory viruses, staffing shortages, and historical closures of inpatient pediatric units. The COVID-19 pandemic and associated surge in critically ill adult patients demonstrated that health care systems and health care workers can quickly implement creative and collaborative system-wide solutions to deliver the best care possible during a capacity crisis. Similar solutions are needed to respond to future surges in pediatric volume and to maintain a high standard of care during such a surge.

Measurements of bone-conducted sound in the chinchilla external ear.

We measure bone-conduction (BC) induced skull velocity, sound pressure at the tympanic membrane (TM) and inner-ear compound-action potentials (CAP) before and after manipulating the ear canal, ossicles, and the jaw to investigate the generation of BC induced ear-canal sound pressures and their contribution to inner-ear BC response in the ears of chinchillas. These measurements suggest that in chinchilla: i.) Vibrations of the bony ear canal walls contribute significantly to BC-induced ear canal sound pressures, as occluding the ear canal at the bone-cartilaginous border causes a 10 dB increase in sound pressure at the TM (P) at frequencies below 2 kHz.

The impact of size on middle-ear sound transmission in elephants, the largest terrestrial mammal.

Elephants have a unique auditory system that is larger than any other terrestrial mammal. To quantify the impact of larger middle ear (ME) structures, we measured 3D ossicular motion and ME sound transmission in cadaveric temporal bones from both African and Asian elephants in response to air-conducted (AC) tonal pressure stimuli presented in the ear canal (P ). Results were compared to similar measurements in humans.

Human middle-ear muscle pulls change tympanic-membrane shape and low-frequency middle-ear transmission magnitudes and delays.

The three-bone flexible ossicular chain in mammals may allow independent alterations of middle-ear (ME) sound transmission via its two attached muscles, for both acoustic and non-acoustic stimuli. The tensor tympani (TT) muscle, which has its insertion on the malleus neck, is thought to increase tension of the tympanic membrane (TM). The stapedius (St) muscle, which has its insertion on the stapes posterior crus, is known to stiffen the stapes annular ligament.

Factors Influencing Palliative Care Access and Delivery for Great Plains American Indians.

Context: Despite the known importance of culturally tailored palliative care (PC), American Indian people (AIs) in the Great Plains lack access to such services. While clinicians caring for AIs in the Great Plains have long acknowledged major barriers to serious illness care, there is a paucity of literature describing specific factors influencing PC access and delivery for AI patients living on reservation land.

Objectives: This study aimed to explore factors influencing PC access and delivery on reservation land in the Great Plains to inform the development culturally tailored PC services for AIs.

Mechanical overstimulation causes acute injury and synapse loss followed by fast recovery in lateral-line neuromasts of larval zebrafish.

Excess noise damages sensory hair cells, resulting in loss of synaptic connections with auditory nerves and, in some cases, hair-cell death. The cellular mechanisms underlying mechanically induced hair-cell damage and subsequent repair are not completely understood. Hair cells in neuromasts of larval zebrafish are structurally and functionally comparable to mammalian hair cells but undergo robust regeneration following ototoxic damage.

Preserving Wideband Tympanometry Information With Artifact Mitigation.

Objective: Absorbance measured using wideband tympanometry (WBT) has been shown to be sensitive to changes in middle and inner ear mechanics, with potential to diagnose various mechanical ear pathologies. However, artifacts in absorbance due to measurement noise can obscure information related to pathologies and increase intermeasurement variability. Published reports frequently present absorbance that has undergone smoothing to minimize artifact; however, smoothing changes the true absorbance and can destroy important narrow-band characteristics such as peaks and notches at different frequencies.

Health Worker Perspectives on Barriers and Facilitators of Assisted Partner Notification for HIV for Refugees and Ugandan Nationals: A Mixed Methods Study in West Nile Uganda.

Assisted partner notification (APN) is recommended by the World Health Organization to notify sexual partners of HIV exposure. Since 2018, APN has been offered in Uganda to Ugandan nationals and refugees. Distinct challenges faced by individuals in refugee settlements may influence APN utilization and effectiveness.

Using Intervention Mapping methodology to design an HIV linkage intervention in a refugee settlement in rural Uganda.

Nearly 80 million people have been forcibly displaced by persecution, violence, and disaster. Displaced populations, including refugees, face health challenges such as resource shortages, food and housing insecurity, violence, and disrupted social support. People living with HIV in refugee settings have decreased engagement with HIV services compared to non-refugee populations, and interventions are needed to enhance linkage to care.

Understanding the role of interpersonal violence in assisted partner notification for HIV: a mixed-methods study in refugee settlements in West Nile Uganda.

Background: Assisted partner notification (APN) for HIV was introduced in refugee settlements in West Nile Uganda in 2018 to facilitate testing of sexual partners. While APN is an effective strategy recommended by the World Health Organization, its safety has not been evaluated in a refugee settlement context in which participants have high prior exposure to interpersonal violence. The extent to which interpersonal violence influences APN utilization and the frequency with which post-APN interpersonal violence occurs remains unknown.

Delivering primary healthcare in conflict-affected settings: A review of the literature.

Objective: Conflict is often destructive to existing services and exacerbates population health inequities and the vulner-abilities of existing healthcare. We undertook a scoping review of the literature concerning delivery of primary healthcare (PHC) in post-conflict settings.

Design: We undertook a scoping review of the peer-reviewed and gray literature to identify articles related to the development and delivery of PHC in post-conflict settings.

Sound pressure distribution within human ear canals: II. Reverse mechanical stimulation.

This work is part of a study of the interactions of ear canal (EC) sound with tympanic membrane (TM) surface displacements. In human temporal bones, the ossicles were stimulated mechanically "in reverse" to mimic otoacoustic emissions (OAEs), and the sound field within the ear canal was sampled with 0.5-2 mm spacing near the TM surface and at more distal locations within the EC, including along the longitudinal EC axis.

Tympanic membrane surface motions in forward and reverse middle ear transmissions.

Characterization of Tympanic Membrane (TM) surface motions with forward and reverse stimulation is important to understanding how the TM transduces acoustical and mechanical energy in both directions. In this paper, stroboscopic opto-electronic holography is used to quantify motions of the entire TM surface induced by forward sound and reverse mechanical stimulation in human cadaveric ears from 0.25 to 18.

Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography.

The sound-driven vibration of the tympanic membrane and ossicular chain of middle-ear bones is fundamental to hearing. Here we show that optical coherence tomography in phase synchrony with a sound stimulus is well suited for volumetric, vibrational imaging of the ossicles and tympanic membrane. This imaging tool - OCT vibrography - provides intuitive motion pictures of the ossicular chain and how they vary with frequency.

Chinchilla middle ear transmission matrix model and middle-ear flexibility.

The function of the middle ear (ME) in transforming ME acoustic inputs and outputs (sound pressures and volume velocities) can be described with an acoustic two-port transmission matrix. This description is independent of the load on the ME (cochlea or ear canal) and holds in either direction: forward (from ear canal to cochlea) or reverse (from cochlea to ear canal). A transmission matrix describing ME function in chinchilla, an animal commonly used in auditory research, is presented, computed from measurements of forward ME function: input admittance Y, ME pressure gain G, ME velocity transfer function H, and cochlear input admittance Y, in the same set of ears [Ravicz and Rosowski (2012b).

Response of the human tympanic membrane to transient acoustic and mechanical stimuli: Preliminary results.

The response of the tympanic membrane (TM) to transient environmental sounds and the contributions of different parts of the TM to middle-ear sound transmission were investigated by measuring the TM response to global transients (acoustic clicks) and to local transients (mechanical impulses) applied to the umbo and various locations on the TM. A lightly-fixed human temporal bone was prepared by removing the ear canal, inner ear, and stapes, leaving the incus, malleus, and TM intact. Motion of nearly the entire TM was measured by a digital holography system with a high speed camera at a rate of 42 000 frames per second, giving a temporal resolution of <24 μs for the duration of the TM response.

Infants' neural responses to facial emotion in the prefrontal cortex are correlated with temperament: a functional near-infrared spectroscopy study.

Accurate decoding of facial expressions is critical for human communication, particularly during infancy, before formal language has developed. Different facial emotions elicit distinct neural responses within the first months of life. However, there are broad individual differences in such responses, so that the same emotional expression can elicit different brain responses in different infants.

Restoration of middle-ear input in fluid-filled middle ears by controlled introduction of air or a novel air-filled implant.

The effect of small amounts of air on sound-induced umbo velocity in an otherwise saline-filled middle ear (ME) was investigated to examine the efficacy of a novel balloon-like air-filled ME implant suitable for patients with chronically non-aerated MEs. In this study, air bubbles or air-filled implants were introduced into saline-filled human cadaveric MEs. Umbo velocity, a convenient measure of ME response, served as an indicator of hearing sensitivity.

The Effect of Ear Canal Orientation on Tympanic Membrane Motion and the Sound Field Near the Tympanic Membrane.

The contribution of human ear canal orientation to tympanic membrane (TM) surface motion and sound pressure distribution near the TM surface is investigated by using an artificial ear canal (aEC) similar in dimensions to the natural human ear canal. The aEC replaced the bony ear canal of cadaveric human temporal bones. The radial orientation of the aEC relative to the manubrium of the TM was varied.

Three-dimensional vibrometry of the human eardrum with stroboscopic lensless digital holography.

The eardrum or tympanic membrane (TM) transforms acoustic energy at the ear canal into mechanical motions of the ossicles. The acousto-mechanical transformer behavior of the TM is determined by its shape, three-dimensional (3-D) motion, and mechanical properties. We have developed an optoelectronic holographic system to measure the shape and 3-D sound-induced displacements of the TM.

Sound pressure distribution within natural and artificial human ear canals: forward stimulation.

This work is part of a study of the interaction of sound pressure in the ear canal (EC) with tympanic membrane (TM) surface displacement. Sound pressures were measured with 0.5-2 mm spacing at three locations within the shortened natural EC or an artificial EC in human temporal bones: near the TM surface, within the tympanic ring plane, and in a plane transverse to the long axis of the EC.

Middle-ear velocity transfer function, cochlear input immittance, and middle-ear efficiency in chinchilla.

The transfer function H(V) between stapes velocity V(S) and sound pressure near the tympanic membrane P(TM) is a descriptor of sound transmission through the middle ear (ME). The ME power transmission efficiency (MEE), the ratio of sound power entering the cochlea to power entering the middle ear, was computed from H(V) measured in seven chinchilla ears and previously reported measurements of ME input admittance Y(TM) and ME pressure gain G(MEP) [Ravicz and Rosowski, J. Acoust.

Inner-ear sound pressures near the base of the cochlea in chinchilla: further investigation.

The middle-ear pressure gain GMEP, the ratio of sound pressure in the cochlear vestibule PV to sound pressure at the tympanic membrane PTM, is a descriptor of middle-ear sound transfer and the cochlear input for a given stimulus in the ear canal. GMEP and the cochlear partition differential pressure near the cochlear base ΔPCP, which determines the stimulus for cochlear partition motion and has been linked to hearing ability, were computed from simultaneous measurements of PV, PTM, and the sound pressure in scala tympani near the round window PST in chinchilla. GMEP magnitude was approximately 30 dB between 0.