Automatic discrimination of phonetically relevant and irrelevant vowel parameters as reflected by mismatch negativity

Abstract

An auditory event-related brain potential called mismatch negativity (MMN) was measured to study the perception of vowel pitch and formant frequency. In the MMN paradigm, deviant vowels differed from the standards either in F0 or F2 with equal relative steps. Pure tones of corresponding frequencies were used as control stimuli. The results indicate that the changes in F0 or F2 of vowels significantly affected the MMN amplitudes. The only variable significantly affecting the MMN latencies was sex which, however, did not have any effect on the amplitudes of the MMN. As expected, the MMN amplitudes increased with an increase in the acoustical difference between the standards and the deviants in all cases. On the average, the amplitudes were lower for the vowels than for the pure tones of equal loudness. However, in vowels, minor frequency changes in F0 produced higher MMN amplitudes than similar relative changes in F2. It was also noted that even the smallest and phonetically irrelevant change in F2 was detected by the MMN process. In overall, the results demonstrate that the MMN can be measured separately for F0 and F2 of vowels, although the MMN responses show large interindividual differences.

The Time Course of Neural Changes Underlying Auditory Perceptual Learning

“…Because changes in MMN amplitude have been shown to predict variations in hit rates and RT (Aaltonen et al 1994;Tiitinen et al 1994;Kraus et al 1996; Amenedo and Escera Menning et al 2000), a correlation analysis between changes in MMN amplitude and changes in the RT and P r was conducted separately. A negative correlation was found between the MMN amplitude and the P r discrimination index (r = −0.83, P < 0.08), indicating that voltage values of MMN were more negative (i.e., increased amplitude) as P r increased.…”

Speech Sound Representation in the Brain

“…The MMN elicited by tones is larger over the right hemisphere (in both children and adults), irrespective of the ear stimulated [Giard et al, 1990;Korpilahti and Lang, 1994;Paavilainen et al, 1991;Csépe, 1995]. However, in response to speech stimuli, the MMN can be symmetric both in adults [Aaltonen et al, 1994;Tremblay et al, 1997] and throughout the school-age years .…”

Pre-Attentive Discriminability of Sound Order as a Function of Tone Duration and Interstimulus Interval: A Mismatch Negativity Study

“…Although the present two MMN experiments did not include conditions with active discrimination tasks and, further, their stimulus parameters were not directly comparable, their results can be generalized to a certain extent: previously it was demonstrated that MMN reflects the perceptual accuracy in several kinds of measures such as the Seashore musicality test measuring the subjects' accuracy in sensory-level discrimination [Lang et al, 1990] and the Karma musicality test measuring the subjects' ability to structure continuous sound material to meaningful units [Tervaniemi et al, 1997;Aaltonen et al, 1994;Alho et al, 1992;Tiitinen et al, 1994;Kraus et al, 1995Kraus et al, , 1996Kraus et al, , 1998]. So, although the MMN elicitation does not require the subjects' voluntary attention it well predicts their performance under attentive control.…”

“…Its occurrence implies an incongruency between the stimulus (event) parameters coded by the cortical [Alho, 1995;Giard et al, 1990, Hari et al, 1984 neural-memory trace and new sensory information [Näätänen, 1992]. Importantly, the MMN latency and amplitude for a change in a given sound parameter correlate with the subject's and patient's accuracy in discriminating this parameter in a separate discrimination task [Aaltonen et al, 1994;Korpilahti and Lang, 1994;Kraus et al, 1995Kraus et al, , 1996Lang et al, 1990;Tervaniemi et al, 1997;Tiitinen et al, 1994]. Thus MMN provides a means for determining the severity of pathologies in auditory perception, these recordings being particularly valuable in assessing deficits in patients who are not motivated to or capable of giving their verbal or motor response during active tone discrimination [Näätänen and Alho, 1997].…”