Effect of noise type and level on focus related fundamental frequency changes

Speech in noise, or Lombard speech, is characterized by increased intensity and higher fundamental frequency as well as lengthened segmental durations as speakers try to maintain a beneficial signal-to-noise ratio to fill both communicative and self-monitoring requirements. The phenomenon has been studied with regard to different noise types and different noise levels, as well as with respect to different communicative tasks (e.g., reading out loud vs. speaking to a real listener). However, there are no studies where the effect has been measured with different noises keeping the loudness levels equal. Here we study the Lombard effect with three different noise types at three levels with equal loudness while varying focus structure to elicit different pitch contours. The results show that people adapt their intonation contours depending on both noise level and type even when the noises are similar with respect to their perceived loudness. This points to a special role for pitch in Lombard speech.