MSD Manual

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Merck & Co., Inc, Kenilworth NJ, USA, known as MSD outside the United States and Canada, provides international versions of The Manuals for both health care professionals and the general public. The Manuals are known outside of the United States and Canada as the MSD Manuals. 

By selecting a language below, you will leave, our US and Canadian site, and be directed to the site in your chosen language. Note that not all features of the US and Canadian sites are available on the international versions.

Consumer Version


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Hearing Tests
When sound waves reach the ear, they are gathered by the funnel-shaped outer ear and are channeled into the middle ear. At the entrance to the middle ear, sound waves hit the tympanic membrane...

3D Models

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Ear: The Organ of Hearing and Balance


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Cover Your Cough!
The best holiday gift


Important: The authors, reviewers, and editors of this material have made extensive efforts to ensure that treatments, drugs, and discussions about medical practice are accurate and conform to the standards accepted at the time of publication. However, constant changes in information resulting from continuing research and clinical experience, reasonable differences in opinions among authorities, unique aspects of individual clinical situations, and the possibility of human error in preparing such an extensive text mean that other sources of medical information may differ from the information on this site. The information on this site is not intended to be professional advice and is not intended to replace personal consultation with a qualified physician, pharmacist, or other health care professional. The reader should not disregard medical advice or delay seeking it because of something found on this site.