A Iivonen

Publications (3)37.88 Total impact

• Source

  Available from: Risto J Ilmoniemi

  Article: Language-specific phoneme representations revealed by electric and magnetic brain responses.

  R Näätänen, A Lehtokoski, M Lennes, M Cheour, M Huotilainen, A Iivonen, M Vainio, P Alku, R J Ilmoniemi, A Luuk, J Allik, J Sinkkonen, K Alho
  [show abstract] [hide abstract]
  ABSTRACT: There is considerable debate about whether the early processing of sounds depends on whether they form part of speech. Proponents of such speech specificity postulate the existence of language-dependent memory traces, which are activated in the processing of speech but not when equally complex, acoustic non-speech stimuli are processed. Here we report the existence of these traces in the human brain. We presented to Finnish subjects the Finnish phoneme prototype /e/ as the frequent stimulus, and other Finnish phoneme prototypes or a non-prototype (the Estonian prototype /õ/) as the infrequent stimulus. We found that the brain's automatic change-detection response, reflected electrically as the mismatch negativity (MMN), was enhanced when the infrequent, deviant stimulus was a prototype (the Finnish /ö/) relative to when it was a non-prototype (the Estonian /õ/). These phonemic traces, revealed by MMN, are language-specific, as /õ/ caused enhancement of MMN in Estonians. Whole-head magnetic recordings located the source of this native-language, phoneme-related response enhancement, and thus the language-specific memory traces, in the auditory cortex of the left hemisphere.
  Nature 02/1997; 385(6615):432-4. · 36.28 Impact Factor
• Article: Explaining the dispersion of the single-vowel occurrences in an F1/F2 space.

  A Iivonen
  [show abstract] [hide abstract]
  ABSTRACT: The variability of the Finnish vowel occurrences on the F1/F2 chart was studied. Repetitions (n = 8 x 10 + 10 = 160) of two syllable types, /hVh/ and /tVt/, produced by a male speaker were analysed. The F1/F2 variability in both contexts was estimated. In the /hVh/ context, the phoneme targets were considerably more peripheral than in the /tVt/ contexts. In the /tVt/ context, the phoneme placements were nearer the upper left corner of the F1/F2 space in /u/, /o/, /a/, and /ae/. That is understandable on the basis of the alveolar tongue blade position: the tongue holds its position nearer the alveolar area during its movement from [t] to [V] and back to [t] compared to the [hVh] articulation. In the latter articulation, the tongue is free to move and the vowel reaches its ideal position. This interpretation was corroborated by means of the test items with an open syllable (/tVV/). In order to explain the variability of the repetitions in one context, the notion of auditory critical band window (CBW) was used. A CBW covers an area on the psychoacoustical F1/F2 plot that comprises 1 bark on the F1 and F2 scales. Its modification CBW-F1 implies that a critical band is presented as a circle comprising the diameter of 1 bark according to the F1 scale. Practically all single F1/F2 points occur within the CBW-F1 circle. In most cases, the variability is smaller than one CBW-F1 circle, but we can consider that a greater amount of repetitions would yield a greater dispersion.(ABSTRACT TRUNCATED AT 250 WORDS)
  Phonetica 02/1995; 52(3):221-7. · 1.60 Impact Factor
• Article: Sound spectra in cleft palate patients with a Sanvenero-Rosselli and modified Honig secondary velopharyngeal flap.

  M L Haapanen, A Iivonen
  [show abstract] [hide abstract]
  ABSTRACT: The averaged sound spectra produced by cleft patients with a Sanvenero-Rosselli (SR, n = 4) and modified Honig (MH, n = 4) velopharyngeal flap were compared with each other and with the spectra produced by 4 healthy controls. Each subject produced 16 sound spectra; the total number of spectra was 432. The results indicated that the averaged sound spectra produced by MH patients resembled more closely the spectra produced by healthy controls, while the spectra by SR patients differed from those of MH patients and controls. It was concluded that the differences in the averaged spectra of SR and MH patients reflected differences in the region of the oral cavity, particularly the oropharynx rather than the region of the nasopharynx. The results of this preliminary study indicate that this topic is worth further studies.
  Folia phoniatrica 02/1992; 44(6):291-6.