Gender Perception of Speech: Dependence on Fundamental Frequency, Implied Vocal Tract Length, and Source Spectral Tilt.

OBJECTIVE: To investigate how listeners use fundamental frequency, implied vocal tract length, and source spectral tilt to infer speaker gender. METHODS: Sound files each containing the vowels /i, æ, ɑ, u/ interspersed by brief silences were synthesized. Each of the 210 stimuli was a combination of 10 values for fundamental frequency and 7 values for implied vocal tract length (and the associated formant frequencies) ranging from male-typical to female-typical, and 3 values for source spectral tilt approximating the voice qualities of breathy, normal, and pressed. Twenty-three listeners judged each synthesized "speaker" as "female" or "male." Generalized linear mixed model analysis was used to determine the extent to which fundamental frequency, implied vocal track length, and spectral tilt influenced listener judgment. RESULTS: Increasing fundamental frequency and decreasing implied vocal tract length resulted in increased probability of female judgment. Two interactions were identified: An increase in fundamental frequency and also a decrease in source spectral tilt (more negative) resulted in a greater increase in the probability of female judgment when the vocal tract length was relatively short. CONCLUSIONS: The relationships among fundamental frequency, implied vocal tract length, source spectral tilt, and probability of female judgment changed across the range of normal values, suggesting that the relative contributions of fundamental frequency and implied vocal tract length to gender perception varied over the ranges studied. There was no threshold of fundamental frequency or implied vocal tract length that dramatically shifted the perception between male and female.

Contribution of left supramarginal and angular gyri to episodic memory encoding: An intracranial EEG study.

The role of the left ventral lateral parietal cortex (VPC) in episodic memory is hypothesized to include bottom-up attentional orienting to recalled items, according to the dual-attention model (Cabeza et al., 2008). However, its role in memory encoding could be further clarified, with studies showing both positive and negative subsequent memory effects (SMEs). Furthermore, few studies have compared the relative contributions of sub-regions in this functionally heterogeneous area, specifically the anterior VPC (supramarginal gyrus/BA40) and the posterior VPC (angular gyrus/BA39), on a within-subject basis. To elucidate the role of the VPC in episodic encoding, we compared SMEs in the intracranial EEG across multiple frequency bands in the supramarginal gyrus (SmG) and angular gyrus (AnG), as twenty-four epilepsy patients with indwelling electrodes performed a free recall task. We found a significant SME of decreased theta power and increased high gamma power in the VPC overall, and specifically in the SmG. Furthermore, SmG exhibited significantly greater spectral tilt SME from 0.5 to 1.6 s post-stimulus, in which power spectra slope differences between recalled and unrecalled words were greater than in the AnG (p = 0.04). These results affirm the contribution of VPC to episodic memory encoding, and suggest an anterior-posterior dissociation within VPC with respect to its electrophysiological underpinnings.

Theta Oscillations in Human Memory.

Theta frequency (4-8 Hz) fluctuations of the local field potential have long been implicated in learning and memory. Human studies of episodic memory, however, have provided mixed evidence for theta's role in successful learning and remembering. Re-evaluating these conflicting findings leads us to conclude that: (i) successful memory is associated both with increased narrow-band theta oscillations and a broad-band tilt of the power spectrum; (ii) theta oscillations specifically support associative memory, whereas the spectral tilt reflects a general index of activation; and (iii) different cognitive contrasts (generalized versus specific to memory), recording techniques (invasive versus noninvasive), and referencing schemes (local versus global) alter the balance between the two phenomena to make one or the other more easily detectable.

Word-level prominence in Persian: An Experimental Study.

Previous literature on the phonetics of stress in Persian has reported that fundamental frequency is the only reliable acoustic correlate of stress, and that stressed and unstressed syllables are not differentiated from each other in the absence of accentuation. In this study, the effects of lexical stress on duration, overall intensity and spectral tilt were examined in Persian both in the accented and unaccented conditions. Results showed that syllable duration is consistently affected by stress in Persian in both the accented and unaccented conditions across all vowel types. Unlike duration, the results for overall intensity and spectral tilt were significant only in the accented condition, suggesting that measures of intensity are not a correlate of stress in Persian but they are mainly caused by the presence of a pitch movement. The findings are phonologically interpreted as suggesting that word-level prominence in Persian is typologically similar to 'stress accent' languages, in which multiple phonetic cues are used to signal the prominence contrast in the accented condition, and stressed and unstressed syllables are different from each other even when the word is not pitch-accented.