Japanese Mora-Timing and Speech Processing: The Case of Devoiced Vowels

1. Japanese Mora-Timing and Speech Processing: The Case of Devoiced Vowels Natasha Warner and Naomi Ogasawara University of Arizona

2. Background on Mora-Timing • Japanese moras are often said to be of approximately equal duration: /tookyoo/ ≈ /karaoke/ µµ µ µ µ µµ µ • “Vowel devoicing” is one influence against regular timing: devoiced vowels are shorter. • /kita/ [ki8ta] ‘North’ /kusa/ [ku8sa] ‘grass’ • /mita/ [mita] ‘saw’ /kuma/ [kuma] ‘bear’

3. Perception and processing • Most devoicing and mora-timing literature is on production. • Kato: duration changes, even compensatory ones, make speech less acceptable to listeners. • If regular timing of moras is very important, listeners may use it in processing speech. • When moras are not regular because of devoicing, this could make processing difficult. • But if listeners use the phonology, they may expect devoicing exactly where it happens.

4. Processing of devoiced vowels • Phoneme monitoring (non-words), with voiced and devoiced vowels both in appropriate and inappropriate environments • Listeners hear [hoki8to] or [hokito][tadZiga] or [tadZi8ga] • “Press the button as fast as you can whenever you hear [i] as in [i, ki, Si,…]” • Lexical decision: real words, “press the button if the thing you hear is a real word” • Example words: [akikan] or [akikan]‘empty can’[genditsu] or [genditsu]‘reality’

5. Examples of stimuli Phon. monitoring Lex. decision [hoki8to] [genditsu] [hokito] [genditsu] Does target mora duration differ in the stimuli?

6. Yes, devoicing shortens stimuli mora dur. (ms) (non-)word dur. (ms) Lex. Decision Target mora duration and total item duration are significantly shorter for devoiced vowels: akikanakikangenditsugenditsu akikanakikangenditsugenditsu Phon. Monit. hokitohokitotadigatadiga hokitohokitotadigatadiga

7. Effect on processing: words Are devoiced stimuli harder to process because they diverge from mora-timing? Reaction Times (ms) Error Rates (%) akikanakikangenditsugenditsu akikanakikangenditsugenditsu No. Phonologically appropriate word forms are easier to process (Lexical decision task).

8. Effect on processing: sounds Voicing env.: appropriate form is easier to process. Phoneme monitoring task:Reaction times (ms) Devoicing env.: No effect. “Devoiced” [i8] is often deleted, making the phoneme hard to recognize. In the devoicing environment, this balances out the preference for the phonologically appropriate form. hokitohokitotadigatadiga

9. Intermediate summary • Vowels that are appropriately voiced or appropriately devoiced are easier to process than those that are inappropriate. • Listeners prefer phonologically appropriate forms, even if that means a vowel is devoiced, and a mora is shorter. •  Phonology outweighs any preference for moras to be regularly timed.

10. A second test: splicing Control perception experiments: target mora spliced into surrounding (non-)word stimulus, so that the only thing that differs between conditions is the /i/-mora itself. h o { k j} t o h o { ki } t o Devoiced moras are significantly shorter.

11. Splicing: hypothesis • Meant as a control, but provides an interesting test of processing of timing compensation. • Port et al.: if one mora is short, others in the word lengthen to compensate. Duration of word remains predictable. • Splicing disturbs any compensation relationship. • If there is word-level compensation, spliced stimuli should be harder to process, because they violate timing patterns.

12. Splicing: perception results Reaction Times (ms) Error Rates (%) Lex. Decision Phon. Monit. Spliced stimuli are no harder to process.

13. Conclusions • Listeners find it easier to process forms with phonologically appropriate (de)voicing, even though moras diverge from regular timing. • Altering the compensation relationship within the word does not hinder processing. • Listeners are sensitive to the phonological patterns in their language, and use them more than any expectation of regular timing in processing.