| threshold of consciousness | The lowest point at which a stimulus sensation can be perceived. (05 Mar 2000) |
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| threshold of island of Reil | The band of transition between the anterior portion of the gray matter of the insula and the anterior perforated substance; it is formed by a narrow strip of olfactory cortex along the lateral side of the lateral olfactory stria. Synonym: threshold of island of Reil. (05 Mar 2000) |
| threshold of nose | A ridge marking the boundary between the nasal cavity proper and the vestibule. Synonym: threshold of nose. (05 Mar 2000) |
| threshold percussion | Percussion effected by means of a glass rod as a plessimeter, the rod being inclined to the wall of the chest or abdomen and touching it only by one extremity. (05 Mar 2000) |
| threshold shift | Measurement of the degree of hearing loss or impairment in terms of a decibel shift from an individual's previous audiogram. (05 Mar 2000) |
| threshold stimulus | A stimulus of threshold strength, i.e., one just strong enough to excite. See: adequate stimulus. Synonym: liminal stimulus. (05 Mar 2000) |
| threshold substance | Any material (e.g., glucose) that is excreted in the urine only when its plasma concentration exceeds a certain value, termed its threshold. Synonym: threshold body. (05 Mar 2000) |
| threshold trait | A trait that falls into natural groups that originate not in categorically distinct causes but in whether or not the outcome attains critical values; e.g., gallstones may result from a categorical cause or from unusual levels of causal factors that themselves show no evidence of grouping. Synonym: liminal trait. (05 Mar 2000) |
| transmission threshold | <epidemiology> Occurs for a parasite when the basic reproductive rate Ro is equal to 1. Below this threshold level the disease is unable to maintain itself within the host population. Typically, for directly transmitted parasites there is a transmission threshold for the host population size. (05 Dec 1998) |
| erythema threshold | The amount of radiation that causes redness of the skin. (09 Oct 1997) |
| fibrillation threshold | Least intensity of an electrical stimulus that will initiate fibrillation. (05 Mar 2000) |
| fusion-inferred threshold test | Employment of the phenomenon of cerebral fusion of binaural sounds to substitute for conventional masking in hearing testing. Synonym: FIT test. (05 Mar 2000) |
| light differential threshold | The smallest difference in light intensity that can be appreciated. (05 Mar 2000) |
| alaryngeal speech | A form of speech achieved after laryngectomy by using either an external vibratory source or the pharyngoesophageal segment as an internal vibratory source. Tracheoesophageal speech may be produced after laryngectomy by surgically diverting exhaled air to the pharynx by a permanently constructed tracheoesophageal fistula. (05 Mar 2000) |
| american speech-language-hearing association | A professional society concerned with the diagnosis, prevention, treatment, and remediation of speech, language, and hearing disorders. (12 Dec 1998) |