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Clinical diagnostic applications of ear-canal reflectance have been researched extensively in the literature, however, the measurement uncertainty associated with the conventional measurement technique using an insert ear probe is unknown in human ear canals. Ear-canal reflectance measured using an ear probe is affected by multiple sources of error, including incorrect estimates of the ear-canal cross-sectional area and oblique ear-probe insertions. In this paper, ear-canal reflectance measurements are reproduced in an occluded-ear simulator and in 54 adult ear canals using two different measurement techniques: a conventional ear probe and a two-microphone probe that enables the separation of reverse- and forward-propagating plane waves. The two-microphone probe is inserted directly into test subjects' ear canals, and the two-microphone method is distinguished by not requiring the ear-canal cross-sectional area to calculate the ear-canal reflectance. The results show a reasonable agreement between the two measurement techniques. The paper further examines the influence of oblique ear-probe insertions and the compensation for such oblique insertions, which results in an improved agreement between the two measurement techniques.

The objective of this paper is to present a unique energy based model of the human outer ear and the tympanic membrane. The developed model employs the Port Hamiltonian modelling approach. The tympanic membrane is modelled as an Euler-Bernoulli beam. The frequency response of the model at speech frequencies which are significant for sound transmission are found to comparable to existing results in literature. This model can also be used for investigation of tympanic membrane rupture or perforations. Future work will include modelling of the ear canal as horn shaped and inclusion of the angular motion of the tympanic membrane.

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. Sound fields were measured with the EC open or occluded. The reverse-driven sound field near the TM had larger and more irregular spatial variations below 10 kHz than with forward sound stimulation, consistent with a significant contribution of nonuniform sound modes. These variations generally did not propagate more than ∼4 mm laterally from the TM. Longitudinal sound field variations with the EC open or blocked were consistent with standing-wave patterns in tubes with open or closed ends. Relative contributions of the nonuniform components to the total sound pressure near the TM were largest at EC natural frequencies where the longitudinal component was small. Transverse variations in EC sound pressure can be reduced by reducing longitudinal EC sound pressure variations, e.g., via reducing reflections from occluding earplugs.

Significance The katydid tympanal ears have outer, middle, and inner ear components analogous to mammalian ears. Unlike mammals, each ear has two tympana exposed to sound both externally and internally, with a delayed internal version arriving via the gas-filled ear canal (EC). The two combined inputs in each ear play a significant role in directional hearing. Here, we demonstrate that the major factor causing the internal delay is the EC geometry. The EC bifurcates asymmetrically, producing two additional internal paths that impose different sound velocities for each tympanum. Therefore, various versions of the same signal reach the ears at various times, increasing the chance to pinpoint the sound source. Findings could inspire algorithms for accurate acoustic triangulation in detection sensors., Located in the forelegs, katydid ears are unique among arthropods in having outer, middle, and inner components, analogous to the mammalian ear. Unlike mammals, sound is received externally via two tympanic membranes in each ear and internally via a narrow ear canal (EC) derived from the respiratory tracheal system. Inside the EC, sound travels slower than in free air, causing temporal and pressure differences between external and internal inputs. The delay was suspected to arise as a consequence of the narrowing EC geometry. If true, a reduction in sound velocity should persist independently of the gas composition in the EC (e.g., air, CO2). Integrating laser Doppler vibrometry, microcomputed tomography, and numerical analysis on precise three-dimensional geometries of each experimental animal EC, we demonstrate that the narrowing radius of the EC is the main factor reducing sound velocity. Both experimental and numerical data also show that sound velocity is reduced further when excess CO2 fills the EC. Likewise, the EC bifurcates at the tympanal level (one branch for each tympanic membrane), creating two additional narrow internal sound paths and imposing different sound velocities for each tympanic membrane. Therefore, external and internal inputs total to four sound paths for each ear (only one for the human ear). Research paths and implication of findings in avian directional hearing are discussed.

The inception of the industrial application of the ultrasound was conditional of several discoveries and inventions. The human ear cannot hear the ultrasound (it is practically its definition), therefore for the initial stimulus can be considered the discovery, there can exist the sound beyond audible frequency. After that there was a challenge to invent the device, which can produce the ultrasound. When such a device was manufactured, and when ultrasound could be modulated in different frequencies and amplitudes, the researchers could start thinking about its industrial application. The first global usage of the ultrasound in the industry was a military application in the detection of the submarines and aircraft. After World War II, there begin application of the ultrasound for peaceful purpose in the industry and medicine.

Squeal noise is normally attributed to the self-excited vibration of the wheel induced by the lateral creepage when the wheel slides laterally on the top of rail. Due to its unique tone characteristics and high sound pressure level, the human ear is very sensitive to it. With the improvement of living standards, people's tolerance for squeal noise is getting lower and lower. In order to mitigate and control squeal noise, it is necessary to analyze the sensitivity of relevant parameters. In this paper, a prediction model is developed to analyze the effect of various parameters on the sound pressure level of squeal noise. The results show that squeal noise can be significantly reduced by decreasing angle of attack and rolling speed. In addition, the sound pressure of squeal noise can be reduced by reasonably controlling the negative slope of creepage. Furthermore, this mathematical model is used to perform a sensitivity analysis. The results show that squeal noise is most sensitive to the parameter of angle of attack, and the reason for this is illustrated. In particular, the analysis shows that modifying the slope of the creepage curve is effective in mitigating squeal noise, which provides a reference for mitigating and controlling squeal noise in practice, such as the application of friction modifiers at wheel/rail interface.

Tinnitus is an unusual sensation of hearing perceived without direct sound source. Given the multiplicity of management methods, a work of schematization of the most used therapies; i.e. Tinnitus Retraining Therapy (TRT), Cognitive and behavioral therapy (CBT), and Phase-out” sound therapy (POST) is led based on the Jastreboff model. Human ear models can be used to predict therapy effectiveness. Therefore, we presented three different models (an electric model, an acoustic model and a finite element model) which we then compared by applying them to two external ear shapes. The first is considered to have an auditory canal of uniform section and the second approaches the real shape of the external ear (variable section). The finite element (FE) model gives the most accurate results seeing that it allows to approach the real dimensions of the outer ear. The acoustic model gives results with a maximum deviation of 7,2 percent compared to the FE model with reduced computation time and simpler manner. The electric model is best suited if we consider the outer ear as a tube of uniform section closed at its end.

A 24 GHz Doppler radar based stethoscope has been modified for non-contact diagnosis of heart sounds in a high-noise environment. By adding a digital single-sideband (SSB) modulator, the very low-frequency and difficult to hear heart sounds detected by this stethoscope were shifted toward the more sensitive part of the human ear’s frequency response.In a quiet environment, the heart sounds heard by the modified radio frequency (RF) stethoscope are shown to be the same as those heard by a conventional stethoscope. However, the modified RF stethoscope has an advantage in an extremely high noise environment, where a conventional stethoscope cannot be used. Under those conditions, the quality of the RF stethoscope’s acoustic response is shown to remain substantially unchanged.

Traditional on-line detection of partial discharge based on ultrasonic method has become an important means to detect the insulation condition of electrical equipment. However, most of its detection is based on the threshold value to realize the function similar to “traffic light”, that is, to detect whether partial discharge occurs or not. Gammatone frequency cepstral coefficient (GFCC) is based on human cochlear model and are widely used in voiceprint identification. This paper proposed an extraction algorithm of the characteristic parameter GFCC, and the PD ultrasonic signals of particle discharge and floating discharge are taken as examples, the GFCC of ultrasonic signals of those discharges are extracted. A preliminary partial discharge ultrasonic identification method based on GFCC is proposed. The method can realize on-line intelligent nonintrusive detection of the insulation state of high-voltage equipment, and break the limitation of traditional detection and diagnosis relying on certain threshold or human ear identification.

The vestibular and cochlear aqueducts serve as additional sound transmission paths and produce different degrees of volume velocity shunt flow in cochlear sound transmission. To investigate its effect on forward and reverse stimulations, a lumped-parameter model of the human ear, which incorporates the third windows, was developed. The model combines a transmission-line ear-canal model, a middle-ear model, and an inner-ear model, which were developed previously by different investigators. The model is verified by comparison with experiments. The intracochlear differential-pressure transfer functions, which reflect the input force to the organ of Corti, were calculated. The results show that middle-ear gain for forward sound transmission is greater than the gain for reverse sound transmission. Changes in the cochlear aqueduct impedance have little effect on forward and reverse stimulations. The vestibular aqueduct has little effect on forward stimulation, but increasing its impedance causes deterioration on reverse stimulation below 300 Hz. Decreasing its impedance increases the excitation effect during reverse stimulation over the entire frequency, especially below 1000 Hz. Moreover, compared with the case without the third windows, the presence of the third windows has little effect on forward stimulation. Whereas, it boosts the reverse stimulation's performance below 300 Hz.

This paper shows an influence of a transducer of a middle ear implant on ear dynamics on the basis of the multi-degree-of-freedom biomechanical system. Results of numerical simulations of an ear model with implant are compared with those of the healthy middle ear. Two variants of damping are analysed. The first one typical for a normal healthy middle ear structure and the second one describes pathological properties of the human ear. Moreover, the behaviour of the transducer under various external excitations is investigated. For some set of parameters, the middle ear with the implant behaves regularly but sometimes even chaotically in case of strong excitation.

In this paper, PATRAN software was used to establish a complete 3D finite element model of human ears, and it was then combined with NASTRAN software to analyze frequency responses. This paper conducted a detailed analysis on the dynamic parameters including umbo and stapes displacements of normal human ears under sound pressures 90 dB and 105 dB. The numerically computational results were compared with experimental data. When the analyzed frequency was less than 1000 Hz, the computational result of numerical simulation was well consistent with the upper limit. When the analyzed frequency was more than 1000 Hz, the computational result of numerical simulation was well consistent with the lower limit. Therefore, the numerically computational model was reliable. In addition, based on the verified model, this paper studied vibration characteristics of spiral basilar membrane after replacing artificial auditory ossicle based on the whole hearing system, and found that vibration characteristics of spiral basilar membrane had an obvious change at low and high frequencies after replacing artificial auditory ossicle TORP. Using finite element method to analyze vibration characteristics of spiral basilar membrane can well predict the hearing recovery effect after replacing artificial auditory ossicle. Compared with normal ears, the vibration level of spiral basilar membrane after replacing artificial auditory ossicle has slowed down in 100 Hz-600 Hz, 2000 Hz-4000 Hz and 7000 Hz-10000 Hz, and has been strengthened in 600 Hz-2000 Hz and 4000 Hz-7000 Hz, which provided some help for the hearing recovery at the high-frequency band.

Sound and air pressure both have an important effect on the ear of human beings. In this paper, we established the finite element model of human middle ear to study the sound transmission mechanism and the stress of human ear under the three conditions of acoustic environment, low pressure acoustic environment and pressure fluctuation environment. Experiment and theoretical calculation were also done in the analysis process. The results show that the surface state of the tympanic membrane can reflect the human auditory sensation to a certain extent. Low pressure can reduce the acoustic energy into human ear, and pressure fluctuation leads the ear to bear great stress and temporary hearing loss. In this paper, the quantification of some objective factors is of great significance to the optimization of some standards and the decoupling of multi environmental effects.

This paper used PATRAN/NASTRAN software to establish a three-dimensional finite element model of human ear and conduct dynamic simulation of hearing system. The correctness of the finite element model was verified through analyzing the tympanic membrane displacement of normal human ear under the sound pressure of 80 dB and comparing with the experimental data. Based on the verified model, this paper qualitatively and quantitatively studied and compared the influence of artificial auditory ossicle with 7 kinds of common materials (titanium, stainless steel, teflon, porous polyethylene, alumina ceramic, EH composites and hydroxylapatite ceramics) on the sound conduction of human ear and the effect of postoperative hearing recovery under different sound pressures (50 dB, 80 dB, 105 dB and 120 dB) at 100-10000 Hz. Results showed that the hearing recovery of human ear had the same effect after replacing artificial auditory ossicle under different sound pressures with different frequency. At different frequencies with the same sound pressure, the postoperative hearing of human ear had different effects after replacing different materials of artificial auditory ossicle. Artificial auditory ossicle of hydroxylapatite ceramics, stainless steel and alumina ceramic had better effect on sound conduction at low frequencies, while artificial auditory ossicle of porous polyethylene and teflon had better effect on sound conduction at high frequencies. Under different sound pressures, replacing artificial auditory ossicle with 7 kinds of common materials showed little difference in the hearing recovery of human ear at each frequency band and had a stable influence on the sound conduction of human ear.

The auditory system detects pressure fluctuations that propagate as waves. It can be considered as a successor of the lateral line system, which enables fish and some amphibians to detect particle accelerations. These indicate the location and swimming direction of near objects. The auditory system in fish extends the detection range of the lateral line system. Accordingly, its original function can be considered to be spatial orientation and mental representation of the acoustic surrounding, rather than communication. Starting with the lateral line system of fish and their auditory system, the human ear and auditory pathway are described. It appears that spatial information is encoded at the earliest stages of auditory processing in the brain. Spatial attributes of sound are Sound sources are localized long before they are recognized or consciously perceived.

This chapter describes the sensitivity of the human ear to sound signals as corresponding to the A-weighting network, which is formed primarily by the total transfer function of the external canal, eardrum, bone chain, and the oval window.

Lower flux leakage designs have become important in the development of microspeakers used in thin and miniaturized mobile phones. We propose four methods to reduce the flux leakage of the magnetic circuit in a microspeaker. Optimization was performed based on the proposed approach by using the response surface method. Electromagnetic analyses were conducted using the finite element method. Experimental results are in good agreement with the simulated results obtained in one degree-of-freedom analysis from 100 to 5 ㎑. Both the simulated and experimental results confirm that one of the proposed methods is much more effective in reducing flux leakage than the other methods. In the optimized method, compared with a default approach, the average radial flux density in the air gap decreased only by 5.5%, the maximum flux leakage was reduced by 28.6%, and the acoustic performance at primary resonance decreased by 0.45 ㏈, which gap is indiscernible to the human ear.

We aim at building and studying artificial hair cells (AHC) based on MEMS technology to understand the extraordinary sound perception of the human ear and build a sensor system with similar properties. These perception properties, i.e. detecting six orders of sound pressure level and simultaneously frequency differences of only 3-5 Hz, are obtained mainly due to the sophisticated biological sensors in the inner ear, called hair cells, which convert the acoustic waves into electric signals. They amplify weak inputs and compress larger ones, known as compressive nonlinearity, thus enabling this impressive dynamic range, typically not captured by current engineering solutions. We tackle this demand by building artificial hair cells on the basis of smart, self-actuated and self-sensing mechanical resonator beams with suitable actuation feedback. Thereby, we take advantage of the fact that the compressive nonlinearity arises naturally in dynamical systems tuned to a bifurcation point. This tuning is achieved by an appropriate feedback loop inspired by physiological models. Initial results on the detection properties of a single AHC will be shown demonstrating amplification and a decreased width of the resonance peak.

Hearing damage induced by blast exposure is a common injury in military personnel involved in most operation activities. Personal hearing protection devices such as earplugs come as a standard issue for Service members; however, it is not clear how to accurately evaluate the protection mechanisms of different hearing protection devices for blast overpressures (BOP). This paper reports a recent study on characterization of earplugs’ protective function to BOP using human cadaver ears and 3D finite element (FE) model of the human ear. The cadaver ear mounted with pressure sensors near the eardrum (P1) and inside the middle ear (P2) and with an earplug inserted was exposed to BOP in the blast test chamber. P1, P2, and BOP at the ear canal entrance (P0) were simultaneously recorded. The measured P0 waveform was then applied at the ear canal entrance in the FE model and the P1 and P2 pressures were derived from the model. Both experiments and FE modeling resulted in the P1 reduction which represents the effective protection function of the earplug. Different earplugs showed variations in pressure waveforms transmitted to the eardrum, which determine the protection level of earplugs.

Most combinations of musical tones are perceived as either consonant, “pleasing” to the human ear, or dissonant, which is “not pleasing.” Despite being largely subjective in nature, sensations of consonance and dissonance can be quantified and then compared to the judgments of human subjects. The following is a description of several simple studies that can be carried out in the classroom of a physics of music or science of sound course.

The reliability of nine measures of the stimulus level in the human ear canal was compared by measuring the sensitivity of behavioral hearing thresholds to changes in the depth of insertion of an otoacoustic emission probe. Four measures were the ear-canal pressure, the eardrum pressure estimated from it and the pressure measured in an ear simulator with and without compensation for insertion depth. The remaining five quantities were derived from the ear-canal pressure and the Thévenin-equivalent source characteristics of the probe: Forward pressure, initial forward pressure, the pressure transmitted into the middle ear, eardrum sound pressure estimated by summing the magnitudes of the forward and reverse pressure (integrated pressure) and absorbed power. Two sets of behavioral thresholds were measured in 26 subjects from 0.125 to 20 kHz, with the probe inserted at relatively deep and shallow positions in the ear canal. The greatest dependence on insertion depth was for transmitted pressure and absorbed power. The measures with the least dependence on insertion depth throughout the frequency range (best performance) included the depth-compensated simulator, eardrum, forward, and integrated pressures. Among these, forward pressure is advantageous because it quantifies stimulus phase.

Innovations in additive manufacturing [three-dimensional (3D) printing] have allowed for the fabrication of objects as complex as the human ear. The visible part of the human outer ear (pinna) serves as a funnel and a natural filter for incoming sound. Spectral cues generated by the pinna help with auditory localization and externalization. In an attempt to preserve spectral cues when using circumaural hearing devices, the present work explored the use of 3D printing to fabricate individualized pinna within custom-designed and fabricated hearing devices. Through 3D scanning, a computer aided design (CAD) model of a pinna from an anthropometric mannequin was generated to replicate human pinnae. Multiple 3D printing technologies were used to fabricate the CAD model, investigating different material options, dimensional accuracies, and overall printing costs. The fabricated pinnae were subjected to acoustic testing to assess spectral cue preservation by comparing mannequin head-related transfer functions obt...

An accurate finite element (FE) model of the human ear can help in understanding the physiological mechanismof human ear and facilitate the design of implantable hearing devices. In this paper,a FE modelof the human ear consisting of the external ear canal, middle ear, and cochlea was developed. The geometry of the external ear canal and middle ear model was based on a fresh specimen of human temporal boneviamicro-computer tomography imaging. A harmonic sound pressure of 90 dB SPL was applied in the ear canal and the multi-field coupled FE analysis was conductedamong the ear canal air, cochlea fluid, and middle ear and cochlea structures. The results were compared with the established physiological data. The satisfactory agreements between the model and published experimental measurementsindicate the middle ear and cochlea functions can be well simulated and further application in terms of human ear can be achieved by the model.

Ultrasound – Refers to sound waves with frequencies higher than 20 kHz, which is higher than the frequencies perceptible to the human ear.

The variation of interior air pressure of high-speed train will lead to the discomfort of the human ear. In this paper, based on the four principle of modeling assumption, according to the structure of human ear and the mechanical properties of eardrum in the anatomy, the differential function model and transfer function model while the eardrum is under the action of the pressure are build in order to study the relationship between air pressure fluctuation and the comfort degree of the human ear. Under the action of the actual air pressure wave, combined with the interior air pressure comfort index, the simulation and analysis to the model are done, and then the quantitative relationship between the eardrum deformation and the comfort of human ear is built.

Spontaneous otoacoustic emissions (SOAEs) are generated by self-sustained cochlear oscillators. Properties of a computational model for a linear array of active oscillators with nearest neighbor coupling are investigated. The model can produce many experimentally well-established properties of SOAEs. (C) 2012 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4730886]

The aim of the present research is to simulate dynamic behavior of the human auditoria peripherals during sound transmission using the equivalent six-degrees-of-freedom lumped parameter mathematical model. Transmissibility analysis was employed to get a better insight into the sound transmission from tympanic membrane to malleus, incus, stapes, and cochlea. Furthermore, transmissibility from each member to corresponding adjacent member was carried out to functional analysis of the human ear. Simulation study illustrated that the results are in agreement with the experimental results published in the literature, and the proposed model provides more information in the dynamic analysis of middle ear biomechanics.

Chest percussion is a traditional technique used for the physical examination of pulmonary injuries and diseases. It is a method of tapping body parts with fingers or small instruments to evaluate the size, consistency, borders, and presence of fluid/air in the lungs and abdomen. Percussion has been successfully used for the diagnosis of such potentially lethal conditions as traumatic and tension pneumothorax. This technique, however, has certain shortcomings, including limitations of the human ear and the subjectivity of the administrator, that lead to overall low sensitivity. Automation of the method by using a standardized percussion source and computerized classification of digitized signals would remove the subjective factor and other limitations of the technique. It would also enable rapid on-site diagnostics of pulmonary traumas when thorough clinical examination is impossible. This paper lays the groundwork for an objective signal classification approach based on a general physical model of a damped harmonic oscillator. Using this concept, critical parameters that effectively subdivide percussion signals into three main groups, historically known as "tympanic," "resonant," and "dull," are identified, opening the possibility for automated diagnostics of air/liquid inclusions in the thorax and abdomen. The key role of damping in forming the character of the percussion signal is investigated using a 3D thorax phantom. The contribution of the abdominal component into the complex multimode spectrum of chest percussion signals is demonstrated.

A finite element (FE) model of the human ear including the ear canal, middle ear, and spiral cochlea was constructed from histological sections of human temporal bone. Multiphysics analysis of the acoustics, structure, and fluid coupling in the ear was conducted in the model. The viscoelastic material behavior was applied to the middle ear soft tissues based on dynamic measurements of tissues in our laboratory. The FE model was first validated using the experimental data obtained in human cadaver ears, and then used to investigate the efficiency of the forward and reverse mechanical driving with middle ear implant, and the passive vibration of basilar membrane (BM) with cochlear implant placed in the cochlear scala tympani. The middle ear transfer function and the cochlear function of the BM vibration were derived from the model. This comprehensive ear model provides a novel computational tool to visualize and compute the implantable hearing devices and surgical procedures.

The human ear canal amplifies the sound pressure level at specific frequency bands. The characteristics of the ear canal are very similar to those of curved cylindrical tube. In this study, the characteristics of sound transfer in human ear canal were measured and the acoustical space of ear canal was reproduced from the canal cavity geometry. For the measurement of sound transfer function in ear canal, a probe microphone and a reference microphone were used. The sound transfer functions were measured for 5 human subjects. To reproduce the acoustical space of the ear canal, two kinds of ear simulator were designed. The first one is a straight cylindrical tube type and the other is a real-shape ear of which geometry was taken from a micro-CT scanning of a human ear. The characteristics of the reproduced apparatus were compared with those of the human and a commercial ear simulator, RA0045 of G.R.A.S. Inc. The comparison results show that the developed apparatus well represent the ear canal characteristics in the low frequency, but have limited coincidence in level over high frequency range.

The cochlea transforms incoming sound pressure into vibrations of the basilar membrane which give rise to neural impulses. Although it has been an object of research for several decades, complete understanding of its behavior is far from complete. Many experiments on real cochlea and many mathematical models have been developed in the past decades. In the biophysical cochlear model of Mammano and Nobili [1, 2], both mechanical and hydrodynamical aspects are treated at a level adequate to the complexity of realistic cochlear structures. In this paper, we analyze the time-frequency resolution of this biophysical cochlear model: analysis is first applied to the passive cochlear model and then extended to the active nonlinear model. Further, we propose the method for signal reconstruction from the cochlear time-frequency response. When applied to active cochlear model response, it could result with the signal which human ear actually hears (with some spectral enhancements and noise suppression).

Consonance and dissonance are subjective perceptions that are reactions of the human ear to whether or not musical intervals sound 'pleasing.' The physical causes of consonance and dissonance are not as well understood as other subjective properties of sound perceived by the ear such as pitch, loudness, and quality (timbre). What follows is an overview of some attempts to quantify these sensations, and a new study with results that can be compared to several 'dissonance metrics'.

Lesion of ossicular chain is a common ear disease impairing the sense of hearing. A comprehensive numerical model of human ear can provide better understanding of sound transmission. In this study, we propose a three-dimensional finite element model of human ear that incorporates the canal, tympanic membrane, ossicular bones, middle ear suspensory ligaments/muscles, middle ear cavity and inner ear fluid. Numerical analysis is conducted and employed to predict the effects of middle ear cavity, malleus handle defect, hypoplasia of the long process of incus, and stapedial crus defect on sound transmission. The present finite element model is shown to be reasonable in predicting the ossicular mechanics of human ear.

Recording cough sounds to objectively quantify coughing was first performed using large reel-to-reel tape recorders more than 40 years ago. Coughs were counted manually, which is an extremely laborious and time-consuming process. Current technologies including digital recording techniques, data compression and improvements in digital storage capacity should make the process of recording and counting coughs suitable for automation; however, to date no accurate, objective cough monitoring device is available. Cough sounds are easily distinguishable from other vocalizations by the human ear and hence it is reasonable to assume that coughs sounds should have characteristic, identifying acoustic properties. However, the acoustic features of spontaneously occurring cough sounds are extremely variable. Furthermore, in even the worst cases of cough, the time spent speaking is an order of magnitude greater than the time spent coughing. It follows that even an algorithm that mistakes only a very small proportion of speech as cough will still have an unacceptable false positive rate. There is a clear need for an objective measure of cough for use in clinical practice, clinical research and trials of novel treatments. In the near future automated ambulatory systems with sufficient accuracy to be of clinical use should be available.

The current impulse noise criteria for the protection against impulse noise injury do not incorporate an objective measure of hearing protection. A new biomechanically-based model has been developed based on improvement of the Auditory Hazard Assessment Algorithm for the Human (AHAAH) using the integrated cochlear energy (ICE) as the damage risk correlate (DRC). The model parameters have been corrected using the latest literature data. The anomalous dose-response inversion behavior of the AHAAH model was eliminated. The modeling results show that the annular ligament (AL) parameters are the dominant cause of the non-monotonic dose-response behavior of AHAAH. Based on parametric optimization analysis, a 40% reduction of the AL compliance from the AHAAH default value removed the dose-response inversion problem, and this value was found to be within the physiological range when compared with experimental data. The transfer functions from the new model are in good agreement with those of the human ear. A dose-response curve based on ICE was developed using the human walk-up temporary threshold shift (TTS) data. Furthermore, the ICE values calculated for the German rifle noise tests show excellent comparison with the injury outcomes, hence providing a significant independent validation of the improved model. The ICE was found to be the best DRC to both large weapons and small arms noise injury data, covering both protected and unprotected exposures, respectively. The new AHAAH model with ICE as the dose metric is adequate for use as a medical standard against impulse noise injury.

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. Tones of 0.2 to 18.4 kHz delivered through the aEC induced surface motions of the TM that were quantified using stroboscopic holography; the distribution of sound in the plane of the tympanic ring P TR was measured with a probe tube microphone. The results suggest that the ear canal orientation has no substantial effect on TM surface motions, but P TR at frequencies above 10 kHz is influenced by the ear canal orientation. The complex TM surface motion patterns observed at frequencies above a few kilohertz are not correlated with simpler variations in P TR distribution at the same frequencies, suggesting that the complex sound-induced TM motions are more related to the TM mechanical properties, shape, and boundary conditions rather than to spatial variations in the acoustic stimulus.

Finite element method was employed in this study to analyze the change in performance of implantable hearing devices due to the consideration of soft tissues’ viscoelasticity. An integrated finite element model of human ear including the external ear, middle ear and inner ear was first developed via reverse engineering and analyzed by acoustic–structure–fluid coupling. Viscoelastic properties of soft tissues in the middle ear were taken into consideration in this model. The model-derived dynamic responses including middle ear and cochlea functions showed a better agreement with experimental data at high frequencies above 3000 Hz than the Rayleigh-type damping. On this basis, a coupled finite element model consisting of the human ear and a piezoelectric actuator attached to the long process of incus was further constructed. Based on the electromechanical coupling analysis, equivalent sound pressure and power consumption of the actuator corresponding to viscoelasticity and Rayleigh damping were calculated using this model. The analytical results showed that the implant performance of the actuator evaluated using a finite element model considering viscoelastic properties gives a lower output above about 3 kHz than does Rayleigh damping model. Finite element model considering viscoelastic properties was more accurate to numerically evaluate implantable hearing devices.

PubMedID: 16527245 A considerable number of the combine harvesters in Turkey are rather old and used without cabs resulting in unhealthy working conditions for their operators. Noise is one of the detrimental factors. This study deals with determining and comparing the noise exposed on the operators of the combines with and without a cab used for wheat harvesting in Turkey. The sound pressure levels (dB) at octave band center frequencies (31.5-8000 Hz) and the sound levels (dBA) at the ear level of the operators were measured on 37 different combine harvesters with four different makes and different years from 1976 to 2001. Fifteen of the combines were without a cab, another 15 had original cabs while remaining seven combines had cabs mounted on them after manufacturing. The sound pressure levels were in a decreasing trend from the lower frequencies to higher frequencies. This trend was more noticeable for the combines with original cab and with the cab mounted after manufacturing compared to the ones without cab. The use of a cab was more effective in the insulation of the noise at the medium and higher frequencies, which have more bothersome effect compared to the lower frequencies. The sound pressure levels were 75-102 dB and 46-89 dB at low (31.5-500 Hz) and high (500-8000 Hz) frequencies for all combines, respectively. The sound pressure levels at the frequency of 4000 Hz at which the human ear is most sensitive were 6-17 dB lower for the combines with the cabs mounted after manufacturing and 9-28 dB lower for the ones with the original cabs compared to the combines without cab. The sound levels were 85-90, 81-83, and 76-81 dBA for the combines without cab, with cab mounted after manufacturing, and with original cab, respectively. The study showed that the use of a cab was useful in the insulation of the noise, particularly at higher frequencies. In addition, it protects the operator from the factors having detrimental effects on the working efficiency such as high temperature and dusty environment. The authors strongly recommend mounting of a cab on to the combines currently being used without a cab in rental system in Turkey to provide healthy working conditions for their operators. © 2006 Elsevier Ltd. All rights reserved.

Die gute Isolation von Niedrigenergiehausern erhoht die Gefahr von Schimmelbildung, da der Wasserdampf nicht entweichen kann. Um das Wasser zu entfernen, mus eine raumlufttechnische Anlage installiert werden. Die Stromungskanale verbinden alle Raume und erzeugen einen akustischen Kurzschlus. Um diese sog. Telefonie zu unterdrucken, mussen Schalldampfer in die Stromungskanale eingebaut werden. Die Schalldampfer erzeugen einen zusatzlichen Druckverlust, der Energie kostet. Die Schalldampfer wurden deshalb aerodynamisch und akustisch optimiert. Die entwickelten Kulissenschalldampfer sind aus verhautetem Kunststoff aufgebaut und dadurch gegen Verschmutzung geschutzt. Die beste Dampfung wird zwischen 1000 und 5000 Hz erreicht. In diesem Frequenzbereich ist das menschliche Gehor am empfindlichsten. Baffle silencers for room ventilating systems in low-energy buildings The good isolation of low-energy buildings increases the risk of mould, because the water vapour cannot escape. To remove the water, a room ventilating system has to be installed. The flow ducts are connecting all the rooms and produce an acoustical short-circuit. To suppress this so-called telephony, silencers must be integrated in the ducts. The silencers produce an additional pressure loss, which costs energy. Therefore the silencer was optimized aerodynamically and acoustically. The new developed baffle silencers are made of plastic material with a sheating outside against the dirt. The best acoustical performance of the silencer is between 1000c/s and 5000c/s. In this frequency range the human ear is most sensitive.

High intensity noise/impulse transmission through a bench model consisting of the simplified ear canal, eardrum, and middle ear cavity was investigated using the CFX/ANSYS software package with fluid-structure interactions. The nondimensional fluid-structure interaction parameter q and the dimensionless impulse were used to describe the interactions between the high intensity pressure impulse and eardrum or tympanic membrane (TM). We found that the pressure impulse was transmitted through the straight ear canal to the TM, and the reflected overpressure at the TM became slightly higher than double the incident pressure due to the dynamic pressure (shocks) effect. Deformation of the TM transmits the incident pressure impulse to the middle ear cavity. The pressure peak in the middle ear cavity is lower than the incident pressure. This pressure reduction through the TM was also observed in our experiments that have dimensions similar to the simulation bench model. We also found that the increase of the pressure ratio as a function of the incident pressure is slightly larger than the linear growth rate. The growth rate of the pressure ratio in this preliminary study suggests that the pressure increase in the middle ear cavity may become sufficiently high to induce auditory damage and injury depending on the intensity of the incident sound noise.

Understanding of the human hearing process requires the quantification of the transient response of the human ear and the human tympanic membrane (TM or eardrum) in particular. Current state-of-the-art medical methods to quantify the transient acousto-mechanical response of the TM provide only averaged acoustic or local information at a few points. This may be insufficient to fully describe the complex patterns unfolding across the full surface of the TM. Existing engineering systems for full-field nanometer measurements of transient events, typically based on holographic methods, constrain the maximum sampling speed and/or require complex experimental setups. We have developed and implemented of a new high-speed (i.e., > 40 Kfps) holographic system (HHS) with a hybrid spatio-temporal local correlation phase sampling method that allows quantification of the full-field nanometer transient (i.e., > 10 kHz) displacement of the human TM. The HHS temporal accuracy and resolution is validated versus a LDV on both artificial membranes and human TMs. The high temporal (i.e., 100k data points) resolution of our HHS enables simultaneous measurement of the time waveform of the full surface of the TM. These capabilities allow for quantification of spatially-dependent motion parameters such as energy propagation delays surface wave speeds, which can be used to infer local material properties across the surface of the TM. The HHS could provide a new tool for the investigation of the auditory system with applications in medical research, in-vivo clinical diagnosis as well as hearing aids design.

In room acoustics, several measures have been defined that are supposed to quantify the apparent source width (ASW) in a hall, being one of the perceptual cues related to spaciousness. The most common ones are the lateral energy fraction (LF), i.e., the ratio between lateral and omnidirectional early energy, and the interaural cross correlation coefficient (IACC), all to be calculated from measured or simulated impulse responses. [Several versions of the LF are known in literature, having different names, generalized here as lateral energy fraction.] According to a method proposed by Berkhout et al. [J. Acoust. Soc. Am. 102, 2757–2770 (1997)], for a fixed source position impulse responses have been measured along an array of closely spaced microphone positions in several halls. The above measures, when calculated from these impulse responses, show large fluctuations with small variations in microphone position due to interference of the different components of the wave field to which the human ear is apparently insensitive. A revision of the measures is discussed, which contributes to the suppression of the interference effects. In order to assess their perceptual significance, the fluctuations have to be related to just-noticeable differences (jnd’s) in ASW. Since very different jnd values are given in the literature, the authors advise that new experiments should be conducted on this point.

Because the human ear ignores small amounts of noise that accompany a strong signal, much of the information in audio files can be thrown away with little loss of fidelity.

This paper summarizes the state of the art in measurements and modeling of musical instruments with regard to vibration and radiation problems. Starting from the general requirements in this particular area, due to the high sensitivity of the human ear, a number of examples are given which are aimed at illustrating the concepts and methods used for investigating these specific mechanical structures. The description of experimental methods focuses on noncontact measurements. The presentation of the numerical methods, in both the time and frequency domain, is illustrated by current questions relative to various stringed and percussive instruments. Some unsolved problems, with special consideration of nonlinear effects, are briefly reviewed.

Click-evoked otoacoustic emissions from the human ear are typically several orders of magnitude smaller than the stimuli that elicit them--a measurement technique that attempts to cancel the stimulus signal from the recorded waveform is therefore typically employed. In practice, an imperfect cancellation of the stimulus is achieved, leaving a "stimulus artifact" that obscures the early part of the emission. Input-output nonlinearities of the transducers used in recording emissions are acknowledged as one source of the stimulus artifact. Here an additional source of this artifact, related to hysteresis in the magnetic "receivers" (loudspeakers) used in such recordings, is identified and discussed.

The purpose of this study is to develop a system that enables location finding of a small sound. The system is composed of a biologically-inspired system which uses a hearing mechanism based on the human ear and a mechanism for perceiving weak signals that uses stochastic resonance. Using this proposed system, we implemented the location finding of small sounds through numerical simulations and hardware experiments. Good results were obtained for the small sound source location finding.

The cochlear microphonic (CM) is one of the electrical signals generated by the human ear in response to sound stimulus. Difficulty in recording this signal and inadequate understanding of its origin have restricted its use for human auditory research. Modelling can help to improve our understanding of this signal. In this paper, an electromechanical model for the generation of the cochlear microphonic is proposed. The results of the model can also explain discrepancies between the basilar membrane and CM tuning curves.