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Disorders of Hearing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Linda M. Luxon, Ronald Hinchcliffe
The ear is divided into the external, the middle and the internal ears (Figure 19.1). The pinna collects sound, and loss of this structure leads to a deterioration in the hearing level of about 5 dB across the speech frequencies. The external ear canal is approximately 2.5 centimetres long, and, while there is no amplification of sound within the external canal, a redistribution of energy in the form of resonant peaks produces an enhancement over the mid-frequency range of hearing with a gain of up to 15 dB at the tympanic membrane across the 2 to 6 kHz region. The middle ear includes the tympanic membrane and the tympanic cavity (middle ear cleft) and, inferiorly, the pharyngotympanic or auditory (eustachian) tube links the middle ear to the nasopharynx.
Sound field, spatial hearing, and sound reproduction
Published in Bosun Xie, Spatial Sound, 2023
The middle ear consists of the eardrum, tympanic cavity, ossicles, associated muscles, ligaments, and Eustachian tube. The eardrum lies at the end of the ear canal and has an average surface area of approximately 66 mm2 and a thickness of approximately 0.1 mm. The ossicles within the tympanic cavity consist of three small bones: the malleus, incus, and stapes. The malleus is attached to the eardrum, the stapes is terminated at the oval window of the inner ear, and the incus is found in between the malleus and the stapes.
A study on relationship between pulsatile tinnitus and temporal bone pneumatization grade
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Shan Tian, Xingyu Fan, Yawei Wang, Zhaohui Liu, Lizhen Wang
In general, it is considered that the PT sounds were originated from TS- SS, the closest vessel to the tympanic cavity (Weissman and Hirsch 2000; Sismanis 2011). It was clinically verified that the SS venous sound would directly induce PT when specific pathologies occurred (Eisenman 2011; Kim CS et al. 2016; Raghavan et al. 2016). According to anatomical structures, the venous sound is propagated into the tympanic cavity through the pathway of TBAC (Topal et al. 2008; Tian et al. 2017). It was hypothesized that the TBAC hyperpneumatization was a direct pathology of PT, because hyperpneumatic air cells would induce acoustic resonance, leading to the significant amplification of venous sound (Tüz et al. 2003; Topal et al. 2008; Al-Esawi et al. 2017).
Polymeric middle ear prosthesis enriched with silver nanoparticles – first clinical results
Published in Expert Review of Medical Devices, 2019
Magdalena Ziąbka, Katarzyna Malec
The bactericidal efficacy tests of Otoimplants modified with silver nanoparticles were also performed using two strains (resistant and sensitive to antibiotics) of Staphylococcus aureus G(+) and two strains (resistant and sensitive to antibiotics) of Escherichia coli G(−) obtained from the Laboratory of Microbiology of the Provincial Hospital in Gdansk, Poland, and two reference strains, ATCC 13,420 and ATCC 25,922. The obtained results precisely described by Ziąbka et al. [16], indicated that the introduction of AgNPs to the middle ear prosthesis inhibited the growth of all the tested bacterial strains, both the E. coli species, representing the Gram-negative bacterial group, as well as the S. aureus species belonging to the Gram-positive bacterial group. The growth was inhibited from 86% to 96% for E. coli and from 96% to 100% for S. aureus. It is noteworthy that the strains of bacteria sensitive to the introduced silver nanoparticles were both sensitive and resistant to antibiotics. Moreover, Otoimplants enriched with different amount of silver nanoparticles were also tested against Staphylococcus aureus ATCC 19,660 and Pseudomonas aeruginosa PAK. The tests have proved that the applied amount of nanosilver eliminated the two species completely. The results were intensively described by Ziąbka et al., [14]. Taking into account the results obtained in both works, during the clinical trials the microbiological assessment was done firstly on swabs taken during the surgery from the middle ear and then at later time intervals on swabs taken from external canal (applied surgical technique – tympanoplasty with myringoplasty that is tympanic membrane reconstruction limits the possibility of obtaining swabs directly from the tympanic cavity after surgery). As a noticeable improvement of hearing gave sufficient information, there was no necessity to reoperate in order to collect material for microbiological analysis. Additionally, while designing the prosthesis one of the assumptions was to obtain bactericidal activity during the surgery, which would shorten the time of convalescence of patients and reduce the need for antibiotics. Another assumption was to provide a bactericidal effect in the long term and in the case of recurring otitis media. However, as one-year observation has not revealed any inflammation in the middle ear, we are not able to take swab from the tympanic cavity. Furthermore, on the basis of our in vitro and in vivo tests we expect that silver ions released from the prosthesis will ensure effective bactericidal activity in the middle ear, only if exudate appears in it.