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This study investigated subjective preference for synthesized “spoken data link” messages to provide initial design guidance for communication displays in the context of NextGen (Next Generation Air Transport System) operations. Ratings of Overall Quality and Comprehension Effort were obtained as a function of voice type, synthesized speech rate, and sentence prosody. Rank-order data analyses showed that both Overall Quality and Comprehension Effort were affected by speech rate: under the “Fast Rate” condition (vs. “Default Rate”), Overall Quality decreases and Comprehension Effort increases. However, the introduction of “Prosodic Emphasis” (pitch and level changes for specific phrases) in Fast Rate sentences produced a relative improvement in both comprehension and quality ratings. For both speaking rates, the introduction of “Prosodic Emphasis” resulted in higher quality ratings and lower comprehension effort ratings. The data suggest that faster speaking rates, which may improve message throughput in a display, may be viable when combined with prosodic emphasis.