The Lombard effect - environmental noise affects speech production - has already been studied extensively for read lab speech. In this study spontaneous dialog speech produced by 24 German speakers has been recorded under noisy conditions and analysed for the Lombard effect. A sophisticated experimental setup using behind-the-ear hearing aid equipment allows us to insert real car noise into the perceived audio stream of speakers while maintaining the normal auditory feedback loop. We found that the main Lombard effects - rising fundamental frequency and intensity . can be confirmed for dialog speech. Speaking rate did not slow down although reported earlier for read speech. We also found that certain rhythmicity features regarding the dynamic of the RMS energy contour change significantly under Lombard conditions but only for the female speakers.
Bibliographic reference. Folk, Laura / Schiel, Florian (2011): "The lombard effect in spontaneous dialog speech", In INTERSPEECH-2011, 2701-2704.