HIGHLIGHTS OF CHI 2000 Thomas G. Holzman, Ph.D. (404)

“The Effect of Task Conditions in the Comprehensibility of Synthetic Speech” – Jennifer Lai (IBM), David Wood (IBM), & Michael Considine (Rice Univ.) 78 adults listened on telephone to six passages Unfamiliar passage content Three lengths of passages: –Short – 100 words (content similar to an ) –Medium – 300 words (similar to long or short Web article) –Long – 500 words (CNN news story) INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE

Lai et al. One set of passages recorded by male voice talent One set of passages synthesized with one of five TTS engines Male and female synthetic voices Half of the listeners could take notes, and half could not

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lai et al. Evaluation –Multiple choice comprehension questions –Verbatim recognition of sentences –Subjective opinions regarding effort required, speaking rate, pleasantness of voice, etc.

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lai et al. Results –Note-taking resulted in significantly better performance (in spite of little use of notes when taking test) –Value of note-taking is much greater for synthetic speech –Significantly better performance on passages read by human in the non-note-taking condition –General decline in performance with length of passage in non-note-taking condition (implications for voice interfaces to Web in automobiles?)

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lai et al. Results (continued) –Most subjects perceived synthetic speech to be more difficult to comprehend than human speech –Although human speech was read at 200 WPM and synthetic at 175 WPM, only 36 subjects thought that the synthetic rate was adequate 33 thought it was too fast or much too fast 9 thought it was too slow

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lai et al. Results (continued) –Users performed significantly better with male synthetic voice than with female synthetic voice –Females showed slight preference for male voice –Males showed no voice gender preferences

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE “Can Computer-Generated Speech Have Gender? An Experimental Test of Gender Stereotype” Eun-Ju Lee, Clifford Nass, & Scott Brave (Stanford Univ.) 24 male & 24 female college undergraduates Procedure: –Computer presents a choice-dilemma situation on screen –After subject reads scenario, computer vocally presents its argument for one of two possible positions –Computer always argued for a minority opinion (based on an empirical pilot study)

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lee et al. Procedure (continued) –Subject voices opinion after hearing computer’s argument –Subject fills out paper-and-pencil questionnaire –Total of six different scenarios Results –Subjects reliably identified gender of voices –Subjects accepted male voice suggestions significantly more than female voice suggestions (p<.001) –Voice x Gender interaction indicated that extent of conformity to male voice was less for female than for male subjects, but still present

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Lee et al. Results (continued) –Subjects found their own gender’s voice more attractive (pleasant, likable, friendly) –Subjects found their own gender’s voice more trustworthy (trustworthy, reliable), with this effect being stronger for the males

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE “Can Computer-Generated Speech Manifest Personality?: An Experimental Test of Similarity-Attraction” Clifford Nass, & Kwan Min Lee (Stanford Univ.) Procedure –36 introverted & 36 extroverted subjects access book description Web site (similar to Amazon), Visually presenting title, author’s name, & picture of book Presenting synthetic speech description/review of book –Synthetic voice sounded either “introverted” or “extroverted”

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Nass & Lee Procedure (continued) –After each review, subjects answered questionnaire about the book and its review –Five books were presented –After all five books were presented, subjects answered a questionnaire about the reviewer

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Nass & Lee Results –Subjects reliably distinguished introverted versus extroverted voices (assessed by questionnaire items) –Introverts found introverted voice more attractive, and extroverts found extroverted voice more attractive –Introverts found introverted voice more credible, and extroverts found extroverted voice more credible –Introverts scored the quality of the review higher when read by introverted voice, and extroverts scored the quality of review higher when read by extroverted voice –Introverts were more likely to buy book reviewed by introverted voice, and extroverts were more likely to buy book reviewed by extroverted voice

INFLUENCES OF SPEECH PARAMETERS ON HUMAN PERFORMANCE Nass & Lee Results (continued) –Introverted subjects liked the reviewer more when the review was read by introverted voice, and extroverted subjects liked the reviewer more when review was read by extroverted voice –Introverted subjects found the reviewer to be more credible when the review was read by introverted voice, and extroverted subjects found the reviewer to be more credible when the review was ready by extroverted voice