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BACKGROUND AND AIMS As an alternative to fresh temporal bones, Thiel conserved specimens can be used in the study of ear mechanics. Conserved temporal bones do not decay, permit long-term experiments and overcome problems with limited access to fresh (frozen) temporal bones. Air conduction motion of the tympanic membrane (TM), stapes (ST) and round window (RW) in Thiel specimens is similar to that of fresh specimens according to reports in the literature. Our study compares this motion directly before and after conservation for the same specimens. METHODS The magnitude of motion of TM, ST and RW elicited by acoustic stimulation via the external auditory canal was measured using single point laser Doppler vibrometry (LDV) accessed through a posterior tympanotomy. For the initial measurements (10 ears), fresh frozen whole heads were thawed for at least 24��h. Afterwards, the entire whole heads were embalmed according to the Thiel embalming method and measurements were repeated 3 and 12 months later. RESULTS The magnitudes of TM, ST and RW motion before and after Thiel conservation differed maximally 10��dB on average. A significant increase in TM motion was observed at low frequencies only after long term conservation (12 months). ST motions decreased significantly between 161 and 5300��Hz after 3 months of Thiel conservation. Over the same time period RW motions decreased significantly between 100 and 161��Hz and 489-788��Hz. The ST and RW motions across all measured frequencies were lower after 3 months by 5.7��dB and 7.1��dB, respectively, without further changes after 12 months of conservation. The mean phase shift between ST and RW motion was only 2.1�� for frequencies below 450��Hz. DISCUSSION AND CONCLUSION Thiel embalming changes motion of TM after long term conservation. ST and RW motion changed mainly after short term conservation. The phase shifts close to 180�� between ST and RW motion indicates that the cochlea was still filled with liquid without air bubbles. The results show that Thiel conserved specimens can be used as an alternative model to fresh frozen preparations with some limitations when studying mechanics of the normal human ear, for example, in implant design.

Typical development and maturation of the auditory system, at both the peripheral and central levels, is essential for the acquisition of speech, language, and auditory skills. The peripheral system generally encodes three basic parameters associated with auditory stimuli-time, frequency, and intensity. These acoustic cues are subsequently processed by the central auditory structures to reach and be perceived by the cerebral cortex. Observations of the human fetal and neonatal ear indicate that the peripheral auditory system is structurally and functionally adult-like at birth. In contrast, the central auditory system exhibits progressive anatomical and physiologic changes until early adulthood. Enriched experience with sound is fundamental and critical to auditory development. The absence of early and prolonged acoustic stimulation delays neuronal maturation, affecting the central auditory nervous system, in particular, and leading to atypical development. The present chapter reviews the various stages of development of the auditory system structures, especially the embryology of the human ear, before briefly presenting the trajectories of typical development of auditory abilities from infants to school-aged children.

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.

An earprint is an impression of the external ear. House breakers may leave their earprints inadvertently when they listen at doors and windows to check if there is anyone inside before breaking and entering a premises. Owing to uniqueness and individualistic characteristics of the human ear, earprints can be used as evidence to link a criminal with the crime. In the recent past, many suspected thieves have been convicted and several burglaries linked due to the presence of similar earprints. This chapter explores various issues relating to earprints: ear morphology, variations, individualization, matching, and the admissibility of earprint evidence in the courts.

Before starting to look at the creative aspects of analog sound synthesis, it's a huge help to develop a basic understanding of the principles of physics governing the whole subject of sound – perhaps because of all the methods of electronic sound creation, analog synthesis is probably the closest to those basic scientific principles. If that means a few hours thinking about what sound really is, how it can most easily be created electronically and how it is interpreted by the human ear, then that time will be more than paid back through a deeper, more intuitive approach to the handling of analog synthesizers, modules and effects. So let's briefly take a look at some very basic physics before starting to look at analog instruments themselves.

This is the period in which the sound is made rational. The human ear hears sounds selectively, and these sounds are filtered further by the brain into the relevant and irrelevant categories. A studio microphone has no such ability, so the Post-Production Sound folk must do it for us. Stray sounds always creep into our track while we are filming; now we can equalize them out. We also can add interesting new sounds to give the picture more life.

Publisher Summary This chapter outlines the basic concepts of ultrasonic propagation in materials, describes some of the most important methods for measuring and interpreting ultrasonic measurements, and focuses on the existing and possible applications of the technique in the food industry. There are two distinct types of applications of ultrasound in the food industry: high and low intensity. Low-intensity ultrasound does not alter the properties of a material and is therefore, non-destructive. This chapter discusses only low intensity applications. . Ultrasound is the study and application of sound waves whose frequency is too high to be detected by the human ear, i.e., above about 16 kHz. It is already an established technique for characterizing the physical properties of many biological and non-biological materials. It is used to obtain information about the properties of a material by measuring the interaction between a high-frequency sound wave and the material through which it propagates. The possibility of using ultrasound to characterize foods has been realized for over half a century. Ultrasound offers a number of advantages over alternative techniques used to characterize food: it is capable of rapid and precise measurements, is non-intrusive and non-invasive, can be applied to systems, which are concentrated and optically opaque, is relatively inexpensive, and can easily be adapted for on-line measurements. The continued development of ultrasound in the food industry depends on the availability of appropriate ultrasonic instrumentation and workers using a systematic approach to the measurement and interpretation of ultrasonic data.

Changes in characteristics of one ear artery of the growing rabbit eight weeks after ipsilateral sympathetic denervation at 3–4 weeks of age were compared to the contralateral vessel. Weight, medial thickness, cross sectional area of media and contractility were reduced and the artery was stiffer. Sensitivity to 1-norepinephrine was increased. Similar results were obtained following decentralization of the superior cervical ganglion indicating that in the absence of adrenergic transmission, arterial wall development is impaired and both structural and functional changes occur.

Publisher Summary This chapter describes the cold-induced vasomotor oscillation in a rabbit's ear and the effector mechanisms. Cold stimulus usually evokes hunting phenomena in peripheral vessels. This phenomenon has been investigated extensively, and it has been made clearer in rabbit's ear vessels. A strictly localized application of subfreeze temperatures would be essential for producing the vasooscillation, which is considered to be different from the vasomotor fluctuation. In an experiment described in the chapter, it was found that when 0.5 mg of adrenaline was injected in a rabbit, the wave patterns changed in various ways. Some indicated increased wave amplitudes whereas others indicated lowered amplitudes. The effects, in this respect, were not consistent. Intravenous injection of α-blocker, phenoxybenzamineand abolished the regular wave patterns immediately. Another ablocker, imidaline given intravenously in doses of 10–20 mg also abolished the fluctuating wave patterns. When the blocker was applied intraperitoneally, the reaction appeared gradually. A unique pattern that indicated the intermittent high waves with interposed inhibition phases appeared transiently. The cold vasooscillations invoked by −7°C antifreeze on the rabbit's ear artery were activated by the stimulus of adrenergic fibers and the inhibition of cholinergic fibers.

Publisher Summary This chapter discusses ultrasound as a diagnostic tool. The principal advantages associated with the use of ultrasound are: (1) at the power levels used in diagnostic applications, it is nondestructive to biological organisms, and (2) as its propagation depends on the mechanical properties of the material through which it is propagating, the use of ultrasound ascertains characteristics of the object being analyzed that are not discernable by using other types of probing energy. The term ultrasonics has been applied to sonic energy having frequencies greater than that to which the human ear can respond. Through the use of low-level ultrasound, it is possible to measure the velocity and absorption coefficients of a given material and by these measurements completely characterize the mode of propagation in a given medium. The propagation of low-energy ultrasound waves involves the generation of ultrasound by means of a transducer and subsequent detection. When the sound source vibrates in the direction of the wave motion, the waves produced are termed “longitudinal waves.”

Publisher Summary This chapter describes the effectiveness of adrenergic transmitter concentrations in synaptic clefts of differing dimensions. The dimensions of the adrenergic neuromuscular synapse show considerable variation in different tissues. In the arterial tree, the synaptic cleft size appears to diminish with vessel diameter. The shortest neuromuscular distance ranges from approximately 20,000 A in the elastic arteries to 1000 A in the smaller arteries, and arterioles. The differing patterns of transmitter distribution and concentration have functional correlates in the contractile responses to nervous activity. In elastic arteries for example, there is no evidence of any special contractile effect, or response resulting from transmitter action on cells closest to the nerve elements. Effector response is the sum total of local transmitter effects on the individual smooth muscle cells in the vessel wall. In muscular arteries, such as the ear artery of the rabbit, there are two phases of response associated with two modes of transmitter excitation.