Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

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Duplex perception is a term used to describe the simultaneous evocation of phonetic and nonphonetic percepts, a phenomenon held by some to reveal the operation of a specialized module for phonetic perception. In a widely cited experiment by Whalen and Liberman (1987), duplex percepts were created by replacing the third formant transition in a synthetic syllable with a sinusoidal tone glide and manipulating the level of the glide relative to the rest of the syllable. We discuss this study, and report four experiments. The first two made a systematic estimate of the "duplexity threshold"-the tone glide level at which a chirp-like sound could be heard as well as the speech-like syllable. In the third and fourth experiments, we used the results of the first to repeat and extend the experimental procedures in the original Whalen and Liberman study. We discuss the differences in outcome, and conclude that our results may be explained without the need to invoke a specialized phonetic module.When certain elements of a speech-like sound are made more intense than or spatially dislocated from the rest, both phonetic and nonphonetic percepts are evoked simultaneously. This phenomenon, originally reported by Rand (1974), has been called duplex perception. It continues to attract attention, both from those who wish to affirm that it indicates something special about phonetic perception and from those who believe it does not. This paper is concerned with an attempt to repeat and extend a widely cited experiment on duplexperceptionby Whalen and Liberman (1987).There are several experimental methods used to demonstrate duplex percepts. In the most commonly reported procedure, a synthetic consonant-vowel syllable is presented to a listener such that the syllable "base"-all of the syllable apart from the initial third formant frequency transition-is played to one ear while the third formant transition is played (in its correct temporal alignment) to the other ear. If the pattern of formant transitions is arranged so that the direction of the third formant transition is the distinctive property that determines the identity of the initial consonant, as seen in Figure 1, it is readily shown that the third formant transition can exert its phonetically contrastive influence, even when presented dichotically with the base. Thus, in the example of Figure 1, the subject will report either "da" or "ga" according to whether the third formant transition is falling or rising. However, in addition to reporting a coherent phonetic percept from the ear to which the base is presented, listeners also typically report hearing simulta-

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