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The human auditory system extracts valid information in noisy environments while ignoring other distractions, relying primarily on auditory attention. Studies have shown that the cerebral cortex responds differently to the sound source locations and that auditory attention is time-varying. In this work, we proposed a data-driven encoder-decoder architecture model for auditory attention detection (AAD), denoted as AAD-transformer. The model contains temporal self-attention and channel attention modules and could reconstruct the speech envelope by dynamically assigning weights according to the temporal self-attention and channel attention mechanisms of electroencephalogram (EEG). In addition, the model is conducted based on data-driven without additional preprocessing steps. The proposed model was validated using a binaural listening dataset, in which the speech stimulus was Mandarin, and compared with other models. The results showed that the decoding accuracy of the AAD-transformer in the 0.15-second decoding time window was 76.35%, which was much higher than the accuracy of the linear model using temporal response function in the 3-second decoding time window (increased by 16.27%). This work provides a novel auditory attention detection method, and the data-driven characteristic makes it convenient for neural-steered hearing devices, especially those who speak tonal languages.

People are exposed to whole-body vibration involving multiple directions during daily life especially travelling in vehicles. This study carries out experimental research on human response to dual-axis lateral and roll vibration. Random and sinusoidal vibration defined at 1 Hz are employed as the stimuli. Corresponding apparent inertia and root mean square of human response are measured to investigate the effect of phase difference as well as the vibration intensity. As a result, the symmetrical effect of the phase difference on the human response is detected. The intensity of roll and lateral vibration shows opposite effects. Partial coherence analysis is conducted, and the dominance of lateral vibration is confirmed. Hence, to improve the ride comfort, the lateral vibration needs a higher priority to be controlled compared to the roll one. The compensation effect of the roll vibration provides an effective way to reduce human response around the resonance frequency as long as the magnitude of it is carefully controlled.

Metal-organic frameworks (MOFs) are composed of metal ions/clusters and organic ligands, showing accessible functional sites, ultra-high porosity, and large specific surface area. Tricopper benzene-1,3,5-tricarboxylate (CuBTC), as a three-dimensional MOF architecture with an open and robust micro-/nanoconfiguration, possesses excellent catalytic performance and superior electric conductivity as compared to bulk MOF. In this study, CuBTC was used as a substrate on which molybdenum disulfide (MoS

Benign paroxysmal positional vertigo (BPPV) is the most common vestibular peripheral disease, and has increasingly become the focus of research on vertigo diseases in recent years. In particular, otolaryngology and neurology societies worldwide have placed a greater focus on the study of BPPV. This article reviews the current diagnosis and treatment status and research progress of benign paroxysmal positional vertigo in China from the aspects of disease etiology, pathology, and pathophysiology. We will also consider potential future research in this field.

The mechanism of the active cochlea relies on a complex interaction between microstructures in the organ of Corti. A significant longitudinal vibration “hotspot” was recently observed in the high-frequency region of the living gerbil cochlea between the Deiters cells and the outer hair cells. A similar phenomenon was also found in guinea pigs with a relatively smaller magnitude. The cause is unknown, but one hypothesis is that this phenomenonis due to the structural constraints between different microstructures. It is not easy to explain the mechanism of hotspots directly from experimental observations. It may also be difficult to image or test if the hotspot will occur in the low-frequency region in the cochlea. We built two three-dimensional finite elementmodels corresponding to the high- and low-frequency regions in the guinea pig cochlea. Responses of the organ of Corti to passive acoustic and outer hair cell electrical excitation were calculated. The two excitations werethen superimposed to predict the active response of the organ of Corti. The hotspot phenomenon in the experiment was reproduced and analyzed in-depth about influencing factors. Our results indicate that hotspots appear in the low-frequency region of the cochlea as well. We hypothesize that the hotspot is a locally originated phenomenon in the cochlea, and the traveling wave further enhances the response to low-frequency excitation. The movement of outer hair cells inclined in the longitudinal direction is the leading cause of the hotspot.

In the cocktail party circumstance, the human auditory system extracts the information from a specific speaker of interest and ignores others. Many studies have focused on auditory attention decoding (AAD), but the stimulation materials were mainly non-tonal languages. We used a tonal language (Mandarin) as the speech stimulus and constructed a Long Short-Term Memory (LSTM) architecture for speech envelope reconstruction based on electroencephalogram (EEG) data. The correlation coefficient between the reconstructed and candidate envelopes was calculated to determine the subject's auditory attention. The proposed LSTM architecture outperformed the linear models. The average decoding accuracy in cross-subject and inter-subject cases varies from 63.02 to 74.29%, with the highest accuracy rate of 89.1% in a decision window of 0.15 s. In addition, the beta-band rhythm was found to play an essential role in identifying the attention and the non-attention state. These results provide a new AAD architecture to help develop neuro-steered hearing devices, especially for tonal languages.

Backgroud: The PEA3 subfamily belongs to the first category of the ETS family, and it consists of three family members, namely, ETV1, ETV4, and ETV5. These members were implicated in the progression of many cancers. But their prognostic roles in head and neck squamous cell carcinoma (HNSCC) remain to be characterized.Methods: Data from multiple open databases were used to analyze the expression, regulation, mutations, immune infiltration, and functional networks of the PEA3 subfamily in patients with HNSCC. Results: The results demonstrated that these patients showed downregulated ETV1 and upregulated ETV4/5 compared with healthy subjects. Furthermore, high expression of ETV4/5 and low expression of ETV1 were linked to the shortened overall survival in patients with HNSCC. The immune infiltration in B cells stimulated the prognosis, and it may have a prognostic medical significance linked to the PEA3 subfamily in HNSCC. These results showed that data mining efficiently revealed the expression of the PEA3 subfamily in HNSCC, but this study requires further large-scale genomic and basic research.Conclusions: This study provided new insight into the prognostic roles of PEA3 subfamily in HNSCC with potential mechanistic values.

The cochlea plays an important role in the mammalian auditory system. Sound-induced cell motion in the cochlea is transformed into electrical signals that are then sent to primary auditory neurons. The most significant feature of the cochlea is the active and nonlinear amplification of faint sounds. This active process cannot be explained via a simple hydromechanical representation of the cochlea, that is, a macromechanic explanation. Although the mechanisms of this amplification are not well understood, cochlear micromechanical behavior is thought to play a significant role. The measurement of in vivo cochlea micromechanical responses is challenging and restricted by technical limitations. Modeling the micromechanics of the cochlea, however, can facilitate the interpretation of experimental observations. In this paper, we reviewed studies in which researchers modeled the cochlear micromechanics, and we discussed various modeling hypotheses, outcomes, and expectations. Key words: auditory; cochlea; cochlear amplifier; cochlear micromechanics; cochlear macromechanics; cochlear models; modeling hypothesis; model validation

The COVID-19 pandemic caused by SARS-CoV-2 seriously threatens global public health. It has previously been confirmed that SARS-CoV-2 is mainly transmitted between people through “respiratory droplets”. Therefore, the respiratory tract mucosa is the first barrier to prevent virus invasion. It is very important to stimulate mucosal immunity to protect the body from respiratory virus infection. Inspired by this, we designed a bionic-virus nanovaccine, which can induce mucosal immunity by nasal delivery to prevent virus infection from respiratory tract. The nanovaccine that mimic virosome is composed of poly(I:C) mimicking viral genetic material as immune adjuvant, biomimetic pulmonary surfactant (bio-PS) liposomes as capsid structure of virus and the receptor binding domains (RBDs) of SARS-CoV-2 is used as a “spike”, so as to completely simulate the structure of the coronavirus. The nanovaccine can be administered by inhaling to imitate the process of SARS-CoV-2 infection through the respiratory tract. Our results demonstrated that the inhalable nanovaccine with bionic virus-like structure has a stronger mucosal protective effect than routine muscle and subcutaneous inoculation. In particular, high titer of secretory immunoglobulin A (sIgA) was detected in respiratory secretions, which effectively neutralize the virus and prevent it from entering the body through the respiratory tract. Through imitating the structure and route of infection, this inhalable nanovaccine strategy might inspire a new approach to the precaution of respiratory viruses.

Objective The purpose of this study was to investigate the effect of a dilated vestibular aqueduct on conductive hearing loss (CHL). A biomechanical method was proposed for modeling the patterns of CHL in patients with large vestibular aqueduct syndrome (LVAS). Study design High resolution computed tomography (CT) scans and pure tone audiometry (PTA) were retrospectively collected from 16 patients who were diagnosed with LVAS. Seventeen ears with measurable air-bone gaps (ABGs) on PTA were applied for model development. The sizes of midpoint, operculum and distal segment were measured from CT to calculate the biomechanical parameters of each vestibular aqueduct. The mechanical effect of the dilated vestibular aqueduct on sound conduction was simulated using a lumped-parameter model. The CHL levels predicted by the model were compared with the observed ABGs at 250, 500 and 1000 Hz respectively. Results The model was able to predict the trend that greater ABGs occurred at lower frequencies, which were consistent with clinical observations. However, deviations between the predicted and the observed ABGs became larger as the frequency increased. None of the correlation coefficients between the radiologic measures and the observed ABG levels were significant. Conclusion These findings lend support to the feasibility of this approach in modeling CHL in LVAS. The presence of a dilated vestibular aqueduct leads to altered impedance and sound pressure, suggesting the impact of a pathological third window. High individual variability of the observed ABGs implies additional factors may also be involved, especially at 500 Hz and 1000 Hz.

The cochlear implant (CI) has an effective habilitation modality for hearing-impaired children by promoting sound perception, vocalization, and language ability. However, the major challenge that remained was the lack of assessment standards for pediatric CI users, especially prelingually deaf children, to evaluate hearing rehabilitation effectiveness. In the present study, we conducted an oddball paradigm with stimuli varying in pure-tone, syllable, and tonal sounds. After implantation, we utilized cortical auditory evoked potential (CAEP) and mismatch negativity (MMN) to obtain time-domain analysis; meanwhile, the source localization was investigated to obtain spatial accuracy of the plasticity in the auditory cortex. P1 started to emerge at the third month after implantation, but its peak level was not significant until the sixth month. The temporal lobe was activated between the third and sixth months after implantation. The MMN waveform was basically normal approximately after 12 months. These results suggest that the auditory system goes through a critical period of rapid development between three and six months and enters a maturation period after 12 months. This work indicates that CAEPs are more suitable for assessing the early auditory system reconstruction, while MMN performs better in evaluating the advanced auditory function. Furthermore, source localization has proven to be an efficient tool in exploring auditory cortex plasticity, especially for pediatric CI users.

The rapid spread of COVID-19 results in a pandemic throughout the world, however, there are currently no specific treatments available. We report the first case of ozonated autohemotherapy for a critically ill patient with COVID-19. The patient was diagnosed with severe acute respiratory distress syndrome (ARDS) and life-threatening refractory hypoxemia within 72 hours of the intensive-care unit (ICU) admission. To improve the oxygen delivery, the ozonated autohemotherapy was performed with 40 µg/ml of ozone in 100 ml of blood for 5 days on this patient, who then recovered from ARDS uneventfully and discharged from hospital after viral clearance. This case suggests ozonated autohemotherapy might be an alternative non-invasive medical treatment for critically ill COVID-19 patients.

Cochlear implants (CIs) provide a tool for hearing reconstruction. How to effectively and reasonably evaluate the auditory rehabilitation level of CI children has always been a difficult problem, especially for those with prelingual deafness. Many studies have used electroencephalograph (EEG) technology for CI users, which have shown that EEG is suitable for clinical postoperative evaluation. This study aims to explore changes of latencies and amplitudes of P1 wave in CI children under auditory stimulation. A pure tone at 1000 Hz was used as the stimuli to induce cortical auditory evoked potentials (CAEP). The characteristics of P1 wave were compared between normal hearing children and CI children over different implantation period. Results show that CI children started to have improved auditory perception after implantation, moreover, their P1 wave amplitude becomes similar to that of normal hearing children after six months. One year after implantation, the characteristics of P1 wave of CI children become similar to those of normal hearing children. Therefore, it seems that P1 could be used as an objective auditory rehabilitation assessing indicator for CI children.

Super-resolution fluorescence imaging reveals a previously unknown novel structure of spectrin in inner ear hair cells., Inner ear hair cells (HCs) detect sound through the deflection of mechanosensory stereocilia. Stereocilia are inserted into the cuticular plate of HCs by parallel actin rootlets, where they convert sound-induced mechanical vibrations into electrical signals. The molecules that support these rootlets and enable them to withstand constant mechanical stresses underpin our ability to hear. However, the structures of these molecules have remained unknown. We hypothesized that αII- and βII-spectrin subunits fulfill this role, and investigated their structural organization in rodent HCs. Using super-resolution fluorescence imaging, we found that spectrin formed ring-like structures around the base of stereocilia rootlets. These spectrin rings were associated with the hearing ability of mice. Further, HC-specific, βII-spectrin knockout mice displayed profound deafness. Overall, our work has identified and characterized structures of spectrin that play a crucial role in mammalian hearing development.

We report a case series of ozonated autohemotherapy of four COVID-19 patients, classified as critically ill (1 patient), severe (1 patient), and moderate (2 patients). Each ozonated autohemotherapy treatment was performed at a concentration of 40 μg/ml of ozone per 100 ml of blood. The number of treatments varied from 1 to 9 depending on the disease severity. All 4 patients, including 1 critically ill patient with severe acute respiratory distress syndrome (ARDS) and life-threatening refractory hypoxemia, recovered uneventfully and were discharged from the hospital after viral clearance. The younger sibling of the critically ill patient was also diagnosed with COVID-19 and developed ARDS with hypoxemia, who received mechanical ventilation through an endotracheal tube and extracorporeal membrane oxygenation (ECMO) support. The overall medical cost for 18 days spent in the intensive care unit (ICU) and 56 days of hospitalization was $139,935 USD. On the other hand, our critically ill patient underwent 9 ozonated autohemotherapy treatments and spent 10 days in the ICU and was discharged on hospital day 30; his hospitalization cost amounted to $15,466.50 USD. This case series suggests that ozonated autohemotherapy may be an alternative noninvasive medical treatment for COVID-19 patients.

Compared with an explicit lumped-parameter model of the micromechanics, a pole-zero description appears to be more abstract, but has the advantage of requiring fewer parameters. This makes it suitable for directly fitting to measured responses, using an overall model of the coupled cochlea. Such a fitting procedure is used with the in vivo measurements of basilar membrane motion, obtained with OCT by Lee at al. (2015). The accuracy of the model is quantified in terms of the average mean square difference between its complex frequency response and those of the measurements, and this error is calculated as a function of the excitation level used in the experiments, for different orders of micromechanical model and with either 1D or 3D fluid coupling. A single-degree-of-freedom micromechanical model, representing a passive cochlea with 2 poles and 1 zero, has a significantly higher error at low excitation levels than at high excitation levels, as expected. The error with a two degree-of-freedom micromechanical model, representing an active cochlea with 4 poles and 3 zeros, is low at both high and low levels of excitation and is further reduced if 3D fluid coupling is assumed. Although the pole-zero model does not lead to a unique lumped-parameter representation, it does indicate some of the properties that such a model must have.

Diesel engine-radiated noise quality prediction is an important topic because engine noise has a significant impact on the overall vehicle noise. Sound quality prediction is based on subjective and objective evaluation of engine noise. The integrated satisfaction index (ISI) is proposed as a criterion for differentiate noise quality in the subjective evaluation, and five psychoacoustic parameters are selected for characterizing and analyzing the noise quality of the diesel engine objectively. The combination of support vector machines (SVM) and genetic algorithm (GA) is proposed in order to establish a model for predicting the diesel engine-radiated noise quality for all operation conditions. The performance of the GA-SVM model is compared with the BP neural network model, and the results show that the mean relative error of the GA-SVM model is smaller than the BP neural network model. The importance rank of the sound quality metrics to the ISI is indicated by the non-parametric correlation analysis. This study suggests that the GA-SVM model is very useful for accurately predicting the diesel engine-radiated noise quality.

As well as generating the far field pressure, which allows wave propagation in the cochlea, the vibration of an individual element of the basilar membrane (BM) will also generate a near field pressure, which increases its mass and gives rise to local longitudinal coupling. This paper compares the efficiency and accuracy of a number of different methods of calculating the near field pressure distribution, and explores the connections between them. In particular it is shown that a common approximation to the wavenumber description of the near field pressure is equivalent, in the spatial domain, to an exponential decay away from the point of excitation. Two important properties of the near field pressure are its maximum amplitude, which is finite if the vibrating element has a finite length, and the value of its spatial integral, which determines the added mass on the BM due to the fluid loading. These properties are calculated as a function of the BM width relative to the width of the fluid chamber. By parameterizing the near field pressure variation in this way, it can be readily incorporated into coupled models of the cochlea, without the considerable computational expense of calculating the full three dimensional pressure field.

An efficient way of describing the linear micromechanical response of the cochlea is in terms of its poles and zeros. Pole-zero models with local scaling symmetry are derived for both one and two degree-of-freedom micromechanical systems. These elements are then used in a model of the coupled cochlea, which is optimised to minimise the mean square difference between its frequency response and that measured on the basilar membrane inside the mouse cochlea by Lee, Raphael, Xia, Kim, Grillet, Applegate, Ellerbee Bowden, and Oghalai [(2016) J. Neurosci. 36, 8160-8173] and Oghalai Lab [(2015). https://oghalailab.stanford.edu], at different excitation levels. A model with two degree-of-freedom micromechanics generally fits the measurements better than a model with single degree-of-freedom micromechanics, particularly at low excitations where the cochlea is active, except post-mortem conditions, when the cochlea is passive. The model with the best overall fit to the data is found to be one with two degree-of-freedom micromechanics and 3D fluid coupling. Although a unique lumped parameter network cannot be inferred from such a pole-zero description, these fitted results help indicate what properties such a network should have.

The motion along the basilar membrane in the cochlea is due to the interaction between the micromechanical behaviour of the organ of Corti and the fluid movement in the scalae. By dividing the length of the cochlea into a finite number of elements and assuming a given radial distribution of the basilar membrane motion for each element, a set of equations can be separately derived for the micromechanics and for the fluid coupling. These equations can then be combined, using matrix methods, to give the fully coupled response. This elemental approach reduces to the classical transmission line model if the micromechanics are assumed to be locally-reacting and the fluid coupling is assumed to be entirely one-dimensional, but is also valid without these assumptions. The elemental model is most easily formulated in the frequency domain, assuming quasi-linear behaviour, but a time domain formulation, using state space method, can readily incorporate local nonlinearities in the micromechanics. Examples of programs are included for the elemental model of a human cochlea that can be readily modified for other species., Highlights • General formulation of an elemental model for cochlear mechanics. • Reduce to the transmission line model for locally-reacting micromechanical and 1D fluid coupling. • Incorporation of non-uniform areas, 3D fluid coupling and non locally-reacting micromechanics. • MATLAB programs for the elemental model in the frequency domain and time domain.

A box shape with constant area is often used to represent the complex geometry in the cochlea, although variation of the fluid chambers areas is known to be more complicated. This variation is account for here by an "effective area", given by the harmonic mean of upper and lower chamber area from previous measurements. The square root of this effective area varies linearly along the cochleae in the investigated mammalian species. This suggests the use of a linearly tapered box model, in which the fluid chamber width and height are equal, but decrease linearly along its length. The basilar membrane width is assumed to increase linearly along the model. An analytic form of the far-field fluid pressure difference due to basilar membrane motion is derived for this tapered model. The distributions of the passive basilar membrane response are calculated using both the tapered and uniform models and compared with human and mouse measurements. The discrepancy between the models is frequency-dependent and becomes small at low frequencies. The tapered model developed here shows a reasonable fit to experimental measurements, when the cochleae are cadaver or driven at high sound pressure level and provides a convenient way to incorporate cochlear geometrical variations.

The dynamic behaviour of thin conical shells can be analysed using a number of numerical methods. Although the overall vibration response of shells has been thoroughly studied using such methods, their physical insight is limited. The purpose of this paper is to interpret some of these numerical results in terms of waves, using the wave finite element, WFE, method. The forced response of a thin conical shell at different frequencies is first calculated using the dynamic stiffness matrix method. Then, a wave finite element analysis is used to calculate the wave properties of the shell, in terms of wave type and wavenumber, as a function of position along it. By decomposing the overall results from the dynamic stiffness matrix analysis, the responses of the shell can then be interpreted in terms of wave propagation. A simplified theoretical analysis of the waves in the thin conical shell is also presented in terms of the spatially-varying ring frequency, which provides a straightforward interpretation of the wave approach. The WFE method provides a way to study the types of wave that travel in thin conical shell structures and to decompose the response of the numerical models into the components due to each of these waves. In this way the insight provided by the wave approach allows us to analyse the significance of different waves in the overall response and study how they interact, in particular illustrating the conversion of one wave type into another along the length of the conical shell.

The operation of each hair cell within the cochlea generates a change in electrical potential at the frequency of the vibrating basilar membrane beneath the hair cell. This electrical potential influences the operation of the cochlea at nearby locations and can also be detected as the cochlear microphonic signal. The effect of such potentials has been proposed as a mechanism for the non-local operation of the cochlear amplifier, and the interaction of such potentials has been thought to be the cause of the broadness of cochlea microphonic tuning curves. The spatial extent of influence of these potentials is an important parameter for determining the significance of their effects. Calculations of this extent have typically been based on calculating the longitudinal resistance of each of the scalae from the scala cross sectional area, and the conductivity of the lymph. In this paper, the range of influence of the electrical potential is examined using an electrical finite element model. It is found that the range of influence of the hair cell potential is much shorter than the conventional calculation, but is consistent with recent measurements.

Preservation of residual hearing after cochlear implantation is now considered an important goal of surgery. However, studies indicate an average post-operative hearing loss of around 20 dB at low frequencies. One factor which may contribute to post-operative hearing loss, but which has received little attention in the literature to date, is the increased stiffness of the round window, due to the physical presence of the cochlear implant, and to its subsequent thickening or to bone growth around it. A finite element model was used to estimate that there is approximately a 100-fold increase in the round window stiffness due to a cochlear implant passing through it. A lumped element model was then developed to study the effects of this change in stiffness on the acoustic response of the cochlea. As the round window stiffness increases, the effects of the cochlear and vestibular aqueducts become more important. An increase of round window stiffness by a factor of 10 is predicted to have little effect on residual hearing, but increasing this stiffness by a factor of 100 reduces the acoustic sensitivity of the cochlea by about 20 dB, below 1 kHz, in reasonable agreement with the observed loss in residual hearing after implantation. It is also shown that the effect of this stiffening could be reduced by incorporating a small gas bubble within the cochlear implant.

The cochlear amplifier that provides our hearing with its extraordinary sensitivity and selectivity is thought to be the result of an active biomechanical process within the sensory auditory organ, the organ of Corti. Although imaging techniques are developing rapidly, it is not currently possible, in a fully active cochlea, to obtain detailed measurements of the motion of individual elements within a cross section of the organ of Corti. This motion is predicted using a two-dimensional finite element model. The various solid components are modelled using elastic elements, the outer hair cells as piezoelectric elements, and the perilymph and endolymph as viscous and nearly incompressible fluid elements. The model is validated by comparison with existing measurements of the motions within the passive organ of Corti, calculated when it is driven either acoustically, by the fluid pressure, or electrically, by excitation of the outer hair cells. The transverse basilar membrane motion and the shearing motion between the tectorial membrane and the reticular lamina are calculated for these two excitation modes. The fully active response of the basilar membrane to acoustic excitation is predicted using a linear superposition of the calculated responses and an assumed frequency response for the outer hair cell feedback.

Understanding of the pathophysiology of hearing process and its connection with pathologic conditions which are linked with hearing loss requires an accurate description of the inner ear geometry. In this study, a semi-automated methodology for three-dimensional (3D) reconstruction of the main inner ear structures: i) scalae, ii) basilar membrane, iii) vestibule, iv) stapes and v) round window is proposed. The methodology is based on the acquisition of microCT images and the employment of appropriate image processing techniques for accurate and semi-automated reconstruction. The Level Set algorithm employed with marching cubes algorithm is the main component of the methodology. The proposed methodology outcome is a 3D representation of the inner ear structures in a geometry format which can be used for further processing for inner ear modeling.

There are more researches on engine fan noise control focusing on reducing fan noise level through optimizing fan structure, and a lot of research achievements have been obtained. However, researches on the effect of fan noise to engine noise quality are lacking. The influences of the effects of fan structure optimization on the engine noise quality are unclear. Thus, there will be a decline in fan noise level, but the deterioration of engine noise quality. Aiming at the above problems, in consideration of fan structure design and engine noise quality, an innovative method to analyze the contribution of fan noise to engine noise quality using psychoacoustic theory is proposed. The noises of diesel engine installing different cooling fans are measured by using the acoustic pressure method. The experiment results are regarded as analysis samples. The model of sensory pleasantness is used to analyze the sound quality of a diesel engine with different cooling fans. Results show that after installing 10-blade fan in medium diameter the sensory pleasantness at each test point is increased, and the increase is 13.53% on average, which indicate the improvement of the engine noise quality. In order to verify the psychoacoustical analysis, the subjective assessment is carried out. The test result shows the noise quality of engine installed 10-blade fan in medium diameter is most superior. 1/3 octave frequency spectrum analysis is used to study the reason of the improvement of engine noise quality. It is found that after installing proper cooling fan the sound pressure level below 400 Hz are obviously increased, the frequency assignment and spectral envelope are more reasonable and a proper cooling fan can optimize the spectrum structure of the engine noise. The psychoacoustic study is applied in the contribution of fan noise to engine noise, and the idea of engine sound quality improvement through the structure optimization is proposed.

Fatigue life and reliability of aero-engine blade are always of important significance to flight safety. The establishment of damage model is one of the key factors in blade fatigue research. Conventional linear Miner’s sum method is not suitable for aero-engine because of its low accuracy. A back propagation neutral network (BPNN) based on the combination of Levenberg-Marquardt (LM) and finite element method (FEM) is used to describe process of nonlinear damage accumulation behavior in material and predict fatigue life of the blade. Fatigue tests of standard specimen made from TC4 are carried out to obtain material fatigue parameters and S-N curve. A nonlinear continuum damage model (CDM), based on the BPNN with one hidden layer and ten neurons, is built to investigate the nonlinear damage accumulation behavior, in which the results from the tests are used as training set. Comparing with linear models and previous nonlinear models, BPNN has the lowest calculation error in full load range. It has significant accuracy when the load is below 500 MPa. Especially, when the load is 350 MPa, the calculation error of the BPNN is only 0.4%. The accurate model of the blade is built by using 3D coordinate measurement technology. The loading cycle in fatigue analysis is defined from takeoff to cruise in 10 min, and the load history is obtained from finite element analysis (FEA). Then the fatigue life of the compressor blade is predicted by using the BPNN model. The final fatigue life of the aero-engine blade is 6.55×104 cycles (10 916 h) based on the BPNN model, which is effective for the virtual design of aero-engine blade.

The reasons for hearing loss are complex and currently the mechanics are not entirely clear. Outer hair cell (OHC) loss is believed to play an important role. Experimental observations shown that damage on OHCs due to ototoxic acid starts from the outermost row to the innermost row, whereas, loss of OHCs due to intense noise exposure occurs from the innermost row to the outermost row. Inspired by these experiments, this study employs the finite element method to develop a detailed model of a slice of the human cochlea including cochlear fine structures. OHC motility is implemented by applying forces at the two ends of the OHCs in response to stereocilia deflection, which are believed to be a key process in cochlear amplification. In this way, the effects of a loss of OHCs due to either intense noise exposure or ototoxic acid can be studied by suppressing forces on individual OHCs. Change of cochlear mechanical amplification and vibration patterns inside the organ of Corti due to different hearing loss mechanisms can thus be predicted.