Volume 135, Issue 2, February 2014
Index of content:
- SPEECH PRODUCTION 
135(2014); http://dx.doi.org/10.1121/1.4861245View Description Hide Description
Describing unidentified sounds with words is a frustrating task and vocally imitating them is often a convenient way to address the issue. This article reports on a study that compared the effectiveness of vocal imitations and verbalizations to communicate different referent sounds. The stimuli included mechanical and synthesized sounds and were selected on the basis of participants' confidence in identifying the cause of the sounds, ranging from easy-to-identify to unidentifiable sounds. The study used a selection of vocal imitations and verbalizations deemed adequate descriptions of the referent sounds. These descriptions were used in a nine-alternative forced-choice experiment: Participants listened to a description and picked one sound from a list of nine possible referent sounds. Results showed that recognition based on verbalizations was maximally effective when the referent sounds were identifiable. Recognition accuracy with verbalizations dropped when identifiability of the sounds decreased. Conversely, recognition accuracy with vocal imitations did not depend on the identifiability of the referent sounds and was as high as with the best verbalizations. This shows that vocal imitations are an effective means of representing and communicating sounds and suggests that they could be used in a number of applications.
135(2014); http://dx.doi.org/10.1121/1.4861342View Description Hide Description
Speech produced in the presence of noise (Lombard speech) is typically more intelligible than speech produced in quiet (plain speech) when presented at the same signal-to-noise ratio, but the factors responsible for the Lombard intelligibility benefit remain poorly understood. Previous studies have demonstrated a clear effect of spectral differences between the two speech styles and a lack of effect of fundamental frequency differences. The current study investigates a possible role for durational differences alongside spectral changes. Listeners identified keywords in sentences manipulated to possess either durational or spectral characteristics of plain or Lombard speech. Durational modifications were produced using linear or nonlinear time warping, while spectral changes were applied at the global utterance level or to individual time frames. Modifications were made to both plain and Lombard speech. No beneficial effects of durational increases were observed in any condition. Lombard sentences spoken at a speech rate substantially slower than their plain counterparts also failed to reveal a durational benefit. Spectral changes to plain speech resulted in large intelligibility gains, although not to the level of Lombard speech. These outcomes suggest that the durational increases seen in Lombard speech have little or no role in the Lombard intelligibility benefit.