Showing papers by "Paavo Alku published in 2003"
TL;DR: The results demonstrate that, first, auditory orienting deficits in autism cannot be explained by sensory deficits and, second, that orienting deficit in autism might be speech–sound specific.
Abstract: In autism, severe abnormalities in social behavior coexist with aberrant attention and deficient language. In the attentional domain, attention to people and socially relevant stimuli is impaired the most. Because socially meaningful stimulus events are physically complex, a deficiency in sensory processing of complex stimuli has been suggested to contribute to aberrant attention and language in autism. This study used event-related brain potentials (ERP) to examine the sensory and early attentional processing of sounds of different complexity in high-functioning children with autism. Acoustically matched simple tones, complex tones, and vowels were presented in separate oddball sequences, in which a repetitive “standard” sound was occasionally replaced by an infrequent “deviant” sound differing from the standard in frequency (by 10%). In addition to sensory responses, deviant sounds elicited an ERP index of automatic sound-change discrimination, the mismatch negativity, and an ERP index of attentional orienting, the P3a. The sensory sound processing was intact in the high-functioning children with autism and was not affected by sound complexity or “speechness.” In contrast, their involuntary orienting was affected by stimulus nature. It was normal to both simple- and complex-tone changes but was entirely abolished by vowel changes. These results demonstrate that, first, auditory orienting deficits in autism cannot be explained by sensory deficits and, second, that orienting deficit in autism might be speech–sound specific.
357 citations
TL;DR: Most symptoms were at their minimum during the first loading session and increased statistically significantly to a peak mean value after three or five vocal loading sessions, and Statistically significant differences in the mean level between the gender or exposure groups emerged for ‘central fatigue’ and ‘symptoms of the neck, shoulders and back’ (gender, humidity and posture had clear effects).
Abstract: Vocal loading-related subjective symptoms were studied in a day-long vocal loading test. The voices of 40 female and 40 male voluntary young students were loaded by having them read aloud a novel for
67 citations
TL;DR: The results suggest that even a short vocal training course might affect positively the self-reported well-being of persons working in a vocally loading occupation, however, to find out the long-term effects of a short training course, a follow-up study would need to be carried out.
Abstract: It is commonly known that occupational voice users suffer from voice symptoms to varying extents. The purpose of this study was to find out the effects of a short (2-day) vocal training course on prof
61 citations
TL;DR: Direct evidence for the orderly left-hemispheric representation of phonemes in human auditory cortex was found.
52 citations
TL;DR: Object naming ability, and an electrophysiologic index of auditory sensory discrimination of speech sounds (the mismatch negativity, MMN) in 4-year-old VLBW prematurely born children are examined.
44 citations
TL;DR: In the 3-year-old children, the sensory processing of vowels exhibited transitional characteristics between those observed in infants and school-age children and appeared to be sensitive to the phonemic aspects of stimulus change.
40 citations
TL;DR: Language context had no effect on the mismatch negativity ERP component elicited by the deviant word stimuli, suggesting that language context does not affect the pre-attentive detection of auditory deviance.
28 citations
TL;DR: A new, simpler proof that the symmetric and antisymmetric polynomials can be regarded as optimal constrained predictors that correspond to predicting from the low-pass and high-pass filtered signal, respectively.
Abstract: The commonly used line spectral frequencies form the roots of symmetric and antisymmetric polynomials constructed from a linear predictor. We provide a new, simpler proof that the symmetric and antisymmetric polynomials can be regarded as optimal constrained predictors that correspond to predicting from the low-pass and high-pass filtered signal, respectively.
26 citations
TL;DR: Results from the performance evaluation of the speech analysis environment are presented, which shows that the analysis environment is able to perform robust and consistent measurements of continuous speech.
Abstract: In order to study vocal loading, we developed a speech analysis environment for continuous speech. The objective was to build a robust system capable of handling large amounts of data while minimizing the amount of user-intervention required. The current version of the system can analyze up to five-minute recordings of speech at a time. Through a semiautomatic process it will classify a speech signal into segments of silence, voiced speech and unvoiced speech. Parameters extracted from the input signal include fundamental frequency, sound pressure level, alpha-ratio and speech segment information such as the ratio of speech to silence. This paper presents results from the performance evaluation of the system, which shows that the analysis environment is able to perform robust and consistent measurements of continuous speech.
10 citations
TL;DR: Experiments with vowels show that, in comparison to the conventional LP, WLSP yields all-pole spectra that model formants with an increased dynamic range between formant peaks and spectral valleys.
Abstract: This study presents a new technique called weighted-sum line spectrum pair (WLSP) where an all-pole filter is defined by using a sum of weighted line spectrum pair polynomials. The WLSP yields a stable all-pole filter of order m, whose autocorrelation function coincides with that of the input signal between indices 0 and m-1. By sacrificing the exact matching at index m, the WLSP models the autocorrelation of the input signal at the indices above m more accurately than conventional linear prediction (LP). Experiments with vowels show that, in comparison to the conventional LP, WLSP yields all-pole spectra that model formants with an increased dynamic range between formant peaks and spectral valleys.
8 citations
TL;DR: A constrained linear predictive model, where the degrees of freedom of the predictor are reduced, is presented and it is shown that this model has the minimum-phase property and forms the basis for a convex space of polynomials with the Minimum Phase property.
06 Apr 2003
TL;DR: Constrained linear predictive models where the constraint is one-dimensional (l = 1) are discussed and stability criteria for these models are derived.
Abstract: Stability of the all-pole model in conventional, unconstrained linear prediction with the autocorrelation criterion is well known. By exerting constraints to the optimisation problem it is possible to define models of order m + l with m parameters. However, traditionally constraints have led to models whose stability is not guaranteed. In this paper, we discuss constrained linear predictive models where the constraint is one-dimensional (l = 1) and derive stability criteria for these models.
01 Jan 2003
06 Apr 2003
TL;DR: Experiments indicate that the new method models the formant structure of wide-band speech more accurately than conventional LP, when the prediction order is smaller than the one required by the sampling frequency.
Abstract: A new linear predictive technique, all-pole modeling with symmetric linear prediction (ASLP), is presented. The starting point of the method is an implementation of conventional linear prediction (LP) with a parallel structure, where two symmetric linear predictors are combined to prefilters represented by first order FIRs. Modification of these prefilters yields the ASLP predictor, which is always minimum phase. Experiments indicate that the new method models the formant structure of wide-band speech more accurately than conventional LP, when the prediction order is smaller than the one required by the sampling frequency.
Proceedings Article•
01 Jan 2003
TL;DR: An all-pole modeling technique, Linear Prediction with Lowfrequency Emphasis (LPLE), which emphasizes the lower frequency range of speech, is presented and shows that the method is well-suited when low-order all- pole models with improved modeling of the lowest formants are needed.
Abstract: An all-pole modeling technique, Linear Prediction with Lowfrequency Emphasis (LPLE), which emphasizes the lower frequency range of speech, is presented. The method is based on first interpreting conventional linear predictive (LP) analyses of successive prediction orders with parallel structures using the concept of symmetric linear prediction. In these implementations, symmetric linear prediction is preceded by simple pre-filters, which are of either low or high frequency characteristics. Combining those symmetric linear predictors that are not preceded by high-frequency pre-filters yields the LPLE predictor. It is proved that the all-pole filters computed by LPLE are always stable. The results show that the method is well-suited when low-order all-pole models with improved modeling of the lowest formants are needed.