Measurements of stapes velocity in live human ears (original) (raw)
Related papers
Audiology and Neurotology, 2006
Methodological differences in sound-induced stapes velocity (Vs) measurements in live and cadaveric ears were examined using fresh cadaveric temporal bones. On average, differences in preparation (sectioning the stapedius tendon, removing the facial nerve, and widely opening the facial recess) had statistically insignificant effects on measured Vs. Differences in the achievable measurement angle (with respect to the axis of piston-like stapes motion) had a significant effect on measured Vs below 2 kHz. These results suggest that much if not all of the differences in Vs measurements between live and cadaveric ears can be explained by the differences in measurement angle between the two preparations. Measurement angle was found to have minimal effect on measured Vs above 2 kHz. This demonstrates that the commonly used method of estimating stapes translational velocity by dividing the measured velocity by the cosine of the measurement angle is not valid above 2 kHz.
Stapes displacement and intracochlear pressure in response to very high level, low frequency sounds
Hearing research, 2017
The stapes is held in the oval window by the stapedial annular ligament (SAL), which restricts total peak-to-peak displacement of the stapes. Previous studies have suggested that for moderate (<130 dB SPL) sound levels intracochlear pressure (PIC), measured at the base of the cochlea far from the basilar membrane, increases directly proportionally with stapes displacement (DStap), thus a current model of impulse noise exposure (the Auditory Hazard Assessment Algorithm for Humans, or AHAAH) predicts that peak PIC will vary linearly with DStap up to some saturation point. However, no direct tests of DStap, or of the relationship with PIC during such motion, have been performed during acoustic stimulation of the human ear. In order to examine the relationship between DStap and PIC to very high level sounds, measurements of DStap and PIC were made in cadaveric human temporal bones. Specimens were prepared by mastoidectomy and extended facial recess to expose the ossicular chain. Meas...
Sheep as a large animal ear model: Middle-ear ossicular velocities and intracochlear sound pressure
Hearing research, 2017
Animals are frequently used for the development and testing of new hearing devices. Dimensions of the middle ear and cochlea differ significantly between humans and commonly used animals, such as rodents or cats. The sheep cochlea is anatomically more like the human cochlea in size and number of turns. This study investigated the middle-ear ossicular velocities and intracochlear sound pressure (ICSP) in sheep temporal bones, with the aim of characterizing the sheep as an experimental model for implantable hearing devices. Measurements were made on fresh sheep temporal bones. Velocity responses of the middle ear ossicles at the umbo, long process of the incus and stapes footplate were measured in the frequency range of 0.25-8 kHz using a laser Doppler vibrometer system. Results were normalized by the corresponding sound pressure level in the external ear canal (PEC). Sequentially, ICSPs at the scala vestibuli and tympani were then recorded with custom MEMS-based hydrophones, while pr...
The Effects of Complex Stapes Motion on the Response of the Cochlea
Otology & Neurotology, 2008
Hypothesis: The piston-like motion of the stapes footplate is the only effective stimulus to the cochlea, and rocking-like stapes motions have no effect on hearing. Background: Studies of the vibration of the stapes in response to acoustic stimulation of the normal ear have revealed a complex movement pattern of its footplate. At low frequencies, the vibrations are predominantly piston-like, but they become increasingly rocking-like at middle and high frequencies. These complex vibrations can be decomposed into a translational, piston-like displacement and 2 rotational movements around the long and short axes of the stapes. The rotational components produce no net volume displacement of the cochlear fluid at some distance from the footplate. Therefore, according to the classic theory of hearing, the rotational motion is not transformed into cochlear activity and a hearing sensation. It was the goal of this study to test this hypothesis experimentally in guinea pigs. Methods: A piezoelectric 3-axis device was used to vibrate the stapes in various desired directions while simultaneously monitoring the actual motion of the stapes by a 3-dimensional laser Doppler interferometer and the cochlear activity by recording the compound action potential. Results: The collected data of the presented study cannot be explained by the current theory of hearing. Conclusion: The qualitative results provide supportive evidence that complex movements of the stapes footplate may lead to cochlear activity. Further experiments are necessary to confirm and quantify these effects.
Hearing Research, 2005
A human temporal-bone preparation was used to determine the effects of various degrees of artificial ossicular fixation on the sound-induced velocity at the input-side (the umbo of the malleus) and the output-side (the stapes) of the ossicular chain. Construction of various degrees of attachment between an ossicle and the surrounding temporal bone provided a range of reduction in ossicular mobility or ''fixations''. The results demonstrate different effects of the fixations on the umbo and stapes velocity: fixations of the stapes or incus produce larger reductions in sound-induced stapes velocity (as much as 40-50 dB with extensive stapes fixation), than reductions in umbo velocity (typically less than 10 dB). Fixations of the malleus produce similar-sized changes in both umbo and stapes velocity. These differential effects are consistent with significant flexibility in the ossicular joints (the incudo-malleolar joint and the incudo-stapedial joint) that permits relative motion between the coupled ossicles. The existence of flexibility in the ossicular joints indicates that joints in the ossicular chain can effect a loss of sound-induced mechanical energy between the umbo and the stapes, with a concomitant reduction in the sound-induced motion of the stapes. The introduction of such losses in sound transmission by the joints raises questions concerning the utility of three ossicles in the mammalian ear. The consequences of ossicular flexibility to ossicular-chain reconstruction is discussed. Also, as examined in a more clinically directed paper [Laryngoscope 115 (2005) 147], the different effects of the various ossicular fixations on the motion of the umbo and malleus may be useful in the diagnosis of the site of fixations in humans with conductive hearing losses caused by such pathologies.
Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones
Journal of the Association for Research in Otolaryngology, 2009
We present the first simultaneous sound pressure measurements in scala vestibuli and scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in scala vestibuli (P SV ) was much greater than scala tympani pressure (P ST ), except for very low and high frequencies where P ST significantly affected the input to the cochlea. The differential pressure (P SV − P ST ) is a superior measure of ossicular transduction of sound compared to P SV alone: (P SV −P ST ) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P SV was not reduced as much. The middle ear gain P SV /P EC and the differential pressure normalized to ear canal pressure (P SV − P ST )/P EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)-situations that cannot be completely quantified by measurements of stapes velocity or scala vestibuli pressure by themselves.
Methods and reference data for middle ear transfer functions
Scientific Reports, 2022
Human temporal bone specimens are used in experiments measuring the sound transfer of the middle ear, which is the standard method used in the development of active and passive middle ear implants. Statistical analyses of these experiments usually require that the TB samples are representative of the population of non-pathological middle ears. Specifically, this means that the specimens must be mechanically well-characterized. We present an in-depth statistical analysis of 478 data sets of middle ear transfer functions (METFs) from different laboratories. The data sets are preprocessed and various contributions to the variance of the data are evaluated. We then derive a statistical range as a reference against which individual METF measurements may be validated. The range is calculated as the two-sided 95% tolerance interval at audiological frequencies. In addition, the mean and 95% confidence interval of the mean are given as references for assessing the validity of a sample group. Finally, we provide a suggested procedure for measuring METFs using the methods described herein. Abbreviations AMEI Active middle ear implant ASTM American Society for Testing and Materials CI Confidence interval dBSPL Decibel sound pressure level dB SPLeq. DB SPL equivalent FFT Fast Fourier transform IQR Interquartile range LDV Laser Doppler vibrometer METF Middle ear transfer function OC Ossicular chain SFP Stapes footplate SFV Stapes footplate velocity SHV Stapes head velocity SNR Signal to noise ratio TB Temporal bone specimen TI Tolerance interval TM Tympanic membrane LDV angle of incidence relative to normal of the SFP Background. Experimental studies using human cadaveric temporal bone (TB) specimens are an important tool for the understanding of middle ear mechanics and the development of new surgical procedures, diagnostics, or devices for hearing rehabilitation. Transferring the insights gained by such studies into real-world applications, however, requires classifying the mechanical properties of the samples used in relation to the population. An important characteristic here is the sound transfer from the tympanic membrane (TM) through the ossicular chain (OC) into the inner ear, which for non-pathological human middle ears and sound pressures of
Mammalian middle ear mechanics: A review
Frontiers in Bioengineering and Biotechnology
The middle ear is part of the ear in all terrestrial vertebrates. It provides an interface between two media, air and fluid. How does it work? In mammals, the middle ear is traditionally described as increasing gain due to Helmholtz’s hydraulic analogy and the lever action of the malleus-incus complex: in effect, an impedance transformer. The conical shape of the eardrum and a frequency-dependent synovial joint function for the ossicles suggest a greater complexity of function than the traditional view. Here we review acoustico-mechanical measurements of middle ear function and the development of middle ear models based on these measurements. We observe that an impedance-matching mechanism (reducing reflection) rather than an impedance transformer (providing gain) best explains experimental findings. We conclude by considering some outstanding questions about middle ear function, recognizing that we are still learning how the middle ear works.
Toynbee Memorial Lecture 1997. Middle ear mechanics in normal, diseased and reconstructed ears
The Journal of Laryngology Otology, 1998
A review of the structure-function relationships in normal, diseased and reconstructed middle ears is presented. Variables used to describe the system are sound pressure, volume velocity and acoustic impedance. We discuss the following: (1) Sound can be transmitted from the ear canal to the cochlea via two mechanisms: the tympanoossicular system (ossicular coupling) and direct acoustic stimulation of the oval and round windows (acoustic coupling). In the normal ear, middle-ear pressure gain, which is the result of ossicular coupling, is frequency-dependent and smaller than generally believed. Acoustic coupling is negligibly small in normal ears, but can play a significant role in some diseased and reconstructed ears. (2) The severity of conductive hearing loss due to middle-ear disease or after tympanoplasty surgery can be predicted by the degree to which ossicular coupling, acoustic coupling, and stapes-cochlear input impedance are compromised. Such analyses are used to explain the air-bone gaps associated with lesions such as ossicular interruption, ossicular fixation and tympanic membrane perforation. (3) With type IV and V tympanoplasty, hearing is determined solely by acoustic coupling. A quantitative analysis of structure-function relationships can both explain the wide range of observed postoperative hearing results and suggest surgical guidelines in order to optimize the post-operative results. (4) In tympanoplasty types I, II and III, the hearing result depends on the efficacy of the reconstructed tympanic membrane, the efficacy of the reconstructed ossicular chain and adequacy of middle-ear aeration. Currently, our knowledge of the mechanics of these three factors is incomplete. The mechanics of mastoidectomy and stapedectomy are also discussed.