This Article  • References  • Full text PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Social Bookmarking   What's this?

OTTO METZ, M.D.

AMA Arch Otolaryngol. 1952;55(5):536-543.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

THE CONTRACTION of the intratympanic muscles brings about a change in the tension of the tympanic membrane and thus in the acoustic resistance or impedance of the ear.¹ This change in impedance may be utilized for examination also of the muscular contraction in ears with normal tympanic membranes—as, for instance, in determination of the threshold value.

PRINCIPLE OF MEASUREMENT OF IMPEDANCE

An acoustic impedance bridge² is employed, the principle of which is very simple: measurement of acoustic impedance by comparison. The impedance to be determined—here, that of the ear—is compared (balanced) with a variable acoustic impedance standard.

The bridge (Fig. 1) consists of a tube (O, B), the ends of which are closed by the impedances to be compared. The telephone membrane (M) sounds to either side. When the impedance is the same in two planes lying symmetrically in relation to the telephone membrane, a pressure node will arise at . . . [Full Text PDF of this Article]

Author Affiliations
COPENHAGEN, DENMARK

From the University Ear Clinic, the Rigshospital (Chief: Prof. A. Thornval, M.D.), Copenhagen, Denmark.

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?