title: Automatic and controlled processing of acoustic and phonetic contrasts.
abstract: Changes in the temporal properties of the speech signal provide important cues for phoneme identification. An impairment or inability to detect such changes may adversely affect one's ability to understand spoken speech. The difference in meaning between the Finnish words tuli (fire) and tuuli (wind), for example, lies in the difference between the duration of the vowel /u/. Detecting changes in the temporal properties of the speech signal, therefore, is critical for distinguishing between phonemes and identifying words. In the current study, we tested whether detection of changes in speech sounds, in native Finnish speakers, would vary as a function of the position within the word that the informational changes occurred (beginning, middle, or end) by evaluating how length contrasts in segments of three-syllable Finnish pseudo-words and their acoustic correlates were discriminated. We recorded a combination of cortical components of event-related brain potentials (MMN, N2b, P3b) along with behavioral measures of the perception of the same sounds. It was found that speech sounds were not processed differently than non-speech sounds in the early stages of auditory processing indexed by MMN. Differences occurred only in later stages associated with controlled processes. The effects of position and attention on speech and non-speech stimuli are discussed.
authors.affiliation: Department of Neuroscience and Department of Otolaryngology, Albert Einstein College of Medicine, 1410 Pelham Parkway S., Bronx, NY, USA. esussman@aecom.yu.edu
authors.forename: Elyse
authors.initials: E
authors.lastname: Sussman
authors.forename: Teija
authors.initials: T
authors.lastname: Kujala
authors.forename: Jaana
authors.initials: J
authors.lastname: Halmetoja
authors.forename: Heikki
authors.initials: H
authors.lastname: Lyytinen
authors.forename: Paavo
authors.initials: P
authors.lastname: Alku
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*