Listener Detection of Objectively Validated Acoustic Features of Speech in Huntington's Disease

BACKGROUND

Subtle progressive changes in speech motor function and cognition begin prior to diagnosis of Huntington's disease (HD).

OBJECTIVE

To determine the nature of listener-rated speech differences in premanifest and early-stage HD (i.e., PreHD and EarlyHD), compared to neurologically healthy controls.

METHODS

We administered a speech battery to 60 adults (16 people with PreHD, 14 with EarlyHD, and 30 neurologically healthy controls), and conducted a cognitive test of processing speed/visual attention, the Symbol Digit Modalities Test (SDMT) on participants with HD. Voice recordings were rated by expert listeners and analyzed for acoustic and perceptual speech features.

RESULTS

Listeners perceived subtle differences in the speech of PreHD compared to controls, including abnormal pitch level and speech rate, reduced loudness and loudness inflection, altered voice quality, hypernasality, imprecise articulation, and reduced naturalness of speech. Listeners detected abnormal speech rate in PreHD compared to healthy speakers on a reading task, which correlated with slower speech rate from acoustic analysis and a lower cognitive performance score. In early-stage HD, continuous speech was characterized by longer pauses, a higher proportion of silence, and slower rate.

CONCLUSION

Differences in speech and voice acoustic features are detectable in PreHD by expert listeners and align with some acoustically-derived objective speech measures. Slower speech rate in PreHD suggests altered oral motor control and/or subtle cognitive deficits that begin prior to diagnosis. Speakers with EarlyHD exhibited more silences compared to the PreHD and control groups, raising the likelihood of a link between speech and cognition that is not yet well characterized in HD.

Influence of analogy instruction for pitch variation on perceptual ratings of other speech parameters

PURPOSE

Analogy is the similarity of different concepts on which a comparison can be based. Recently, an analogy of "waves at sea" was shown to be effective in modulating fundamental frequency (F0) variation. Perceptions of intonation were not examined, as the primary aim of the work was to determine whether analogy instruction had a negative impact on other parameters of the speech signal compared with explicit instruction. The purpose of this study was (a) to determine whether changes in the standard deviation of F0, acoustically, resulted in similar changes in the perception of pitch variability and (b) to determine the perceptual influence of analogy vs. explicit instructions on speech naturalness, loudness, and rate.

METHOD

Ten speech-language pathologists were asked to listen to and rate pitch variation, speech naturalness, loudness, and rate for 74 Cantonese speech samples using a visual analogue scale, which allowed raters to indicate their subjective perceptions of each parameter.

RESULTS

It is revealed that listeners perceived pitch variation to be greater and speech to be more natural in analogy-instructed, rather than explicitly instructed, speech. No differences were perceived for ratings of speech loudness or speech rate.

CONCLUSION

It is concluded that analogy instruction has a less negative impact on the naturalness of speech than explicit instruction and may provide a better method by which to manipulate desired pitch variation.