In United States v. Dionisio, 410 U.S. 1 (1973), the United States Supreme Court held that a grand jury directive to furnish a voice exemplar for comparison to voices on wire tap recordings did not infringe upon a privacy interest. The Court said: "The physical characteristics of a person's voice, its tone and manner, as opposed to the content of a specific conversation, are constantly exposed to the public. Like a man's facial characteristics, or handwriting, his voice is repeatedly produced for others to hear. No person can have a reasonable expectation that others will not know the sound of his voice, any more than he can reasonably expect that his face will be a mystery to the world." Id. at 14. These words from the Supreme Court in Dionisio strongly suggest that there can be no legitimate expectation of privacy in the appearance of one's eyes, even if they are temporarily concealed by sunglasses. The Court held that voice recordings "were to be used solely to measure the physical properties of the witnesses' voices, not for the testimonial or communicative content of what was to be said." The Court explained that "while one's voice and handwriting are, of course, means of communication," a voice or handwriting exemplar "is an identifying physical characteristic," not testimony, and therefore outside the Fifth Amendment's protection. Id. at 6-7