Lognormal distribution of pause length in ataxic dysarthria

Previous investigations indicated that pauses in ataxic dysarthric speech are abnormal, but little is known about the nature of their variation or whether it can be characterized by a common distribution. The following types of pauses were measured in spontaneous monologues of 16 speakers with ataxic dysarthria: pauses that contained evidence of respiration, pauses that occurred between words, between phonemes, within phonemes, and those associated with stop consonants. Results showed that the duration of pauses not associated with stop consonants can be modeled with two distinct lognormal distributions. The lognormal distribution predicted duration across pause types within 1.67% standard error, with the exception of pauses that occurred within phonemes. Distributional parameters pointed to some fundamental similarities between pauses that occur within words. The robustness of the lognormal distribution across pause types strongly supports this distribution as a viable and useful method of analysis. We hope this work will encourage others to consider the lognormal distribution.