Diplophonia is the simultaneous production by the voice of two separate tones. In diplophonia, or diplothongia as it is sometimes called, two sources of tone operate at the same time. The tones are usually similar in quality and loudness, but distinctly different in pitch. This problem can be distressing to the speaker and amusing to the listener.' Diplophonia, a relatively uncommon phenomenon, is generally regarded as a symptom of laryngeal pathology. We recently observed and intensively studied an 18-year-old girl who possessed the ability to produce diplophonia in the absence of a pathologic lesion. The objective of this paper is to discuss the differential diagnosis of diplophonia and present an analysis of the findings in this unusual case.Diplophonia has been attributed to simultaneous vibration of the vocal cords and the ventricular bands or the tissues of the pharynx. Double voice or alternating voice is nearly always present in the early stages of dysphonia plicae ventricularis," a pathologic entity due to phonation with the ventricular bands. This sometimes

The clinical interpretation of acoustic reflex test results in ears with sensorineural impairment should be based on a consideration of three characteristics of the response: the reflex threshold hearing level, the reflex threshold sensation level, and the decay of the reflex. Examination of results in 152 ears with cochlear pathology and in 152 ears with acoustic tumor indicated that in some cases the combination of characteristics may be contradictory as to site of lesion. Regarding a contradictory response pattern as questionable — neither confirming nor denying a specific site of lesion — improves the predictive accuracy of the test through a reduction in the number of false identifications.

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Critical bandwidth measurements and sensitivity prediction from the acoustic reflex (SPAR) test results were obtained on 20 normal-hearing and two groups of 10 hearing-impaired subjects each representing mild-to-moderate and severe hearing loss. Results of critical bandwidth measurements indicated that for center frequencies of 1000 and 2000 Hz the critical bandwidth was significantly greater for the hearing-impaired subjects. A statistical analysis of the differences in critical bandwidth between those predicted by the SPAR test to have a mild-to-moderate hearing loss and those subjects for whom the test predicted severe hearing loss indicated no differences in critical bandwidth at 2000 Hz. A significant difference was found at 1000 Hz but in the wrong direction. Analysis of the relationship between predicted slope of hearing loss and critical bandwidth also failed to show significance. Although the data for hearing-impaired subjects fail to support the rationale for the SPAR test, the results for the entire research sample offer substantial support. Further, the ability of the test to predict categorically degree of hearing loss was also strongly supported.

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