7 research outputs found
One-sided versus two-sided stochastic descriptions
It is well-known that discrete-time finite-state Markov Chains, which are
described by one-sided conditional probabilities which describe a dependence on
the past as only dependent on the present, can also be described as
one-dimensional Markov Fields, that is, nearest-neighbour Gibbs measures for
finite-spin models, which are described by two-sided conditional probabilities.
In such Markov Fields the time interpretation of past and future is being
replaced by the space interpretation of an interior volume, surrounded by an
exterior to the left and to the right.
If we relax the Markov requirement to weak dependence, that is, continuous
dependence, either on the past (generalising the Markov-Chain description) or
on the external configuration (generalising the Markov-Field description), it
turns out this equivalence breaks down, and neither class contains the other.
In one direction this result has been known for a few years, in the opposite
direction a counterexample was found recently. Our counterexample is based on
the phenomenon of entropic repulsion in long-range Ising (or "Dyson") models.Comment: 13 pages, Contribution for "Statistical Mechanics of Classical and
Disordered Systems
Limiares de reconhecimento de sentenças em indivĂduos normo-ouvintes na presença de ruĂdo incidente de diferentes Ăąngulos Sentences recognition thresholds in normal hearing individuals in the presence of inciding noise from different angles
OBJETIVO: Determinar e comparar os limiares de reconhecimento de sentenças no ruĂdo, em campo livre, na presença de ruĂdo incidente de diferentes Ăąngulos e verificar qual a condição de escuta mais desfavorĂĄvel, em indivĂduos normo-ouvintes. MĂTODOS: Aplicou-se o teste Listas de Sentenças em PortuguĂȘs em 38 adultos jovens, avaliados em cabine acĂșstica. As sentenças foram apresentadas a 0°- 0Âș azimute e o ruĂdo competitivo a 0°- 0°, 0Âș- 90Âș, 0Âș - 180° e 0Âș - 270Âș azimute, em intensidade fixa de 65 dB NPS (A). RESULTADOS: As relaçÔes sinal-ruĂdo nas quais foram obtidos os limiares de reconhecimento de sentenças no ruĂdo para estes Ăąngulos de incidĂȘncia foram, respectivamente: -7,56, -11,11, -9,75 e -10,43 dB. Houve diferença entre os resultados nas condiçÔes: 0Âș- 0Âș e 0Âș - 90Âș; 0Âș - 0Âș e 0Âș - 180Âș; - 0Âș - 0Âș e 0Âș - 270Âș. CONCLUSĂO: Os seguintes limiares de reconhecimento de sentenças no ruĂdo, em campo livre, foram obtidos nessas relaçÔes sinal/ruĂdo: 0° - 0° = -7,56 dB; -0Âș - 90Âș = -11,11 dB; -0Âș - 180° = -9,75 dB; 0Âș - 270Âș = -10,43 dB. Os melhores limiares no ruĂdo foram obtidos com os Ăąngulos de incidĂȘncia de 0Âș - 90Âș e 0Âș - 270Âș, seguidos pela condição de 0Âș - 180Âș e, por Ășltimo, 0Âș - 0Âș. A condição de escuta no ruĂdo mais desfavorĂĄvel foi aquela na qual o ruĂdo encontra-se no mesmo Ăąngulo de incidĂȘncia da fala, na posição frontal do indivĂduo avaliado.<br>PURPOSE: To determine and compare the sentence recognition thresholds in the noise, in sound field, in the presence of incident noise from different angles, and to verify the most unfavorable hearing condition, in normal-hearing individuals. METHODS: The Portuguese Sentences Lists test was carried out in 38 young adults, evaluated in acoustic booth. The sentences were presented at 0Âș - 0Âș azimuth, and the competitive noise at 0Âș - 0°, 0° - 90°, 0° - 180°, and 0° - 270° azimuth, in a fixed loudness of 65 dB NPS (A). RESULTS: The signal-to-noise ratios in which the sentence recognition thresholds were obtained for these incidence angles were, respectively: -7.56, -11.11, -9.45, and -10.43 dB. Differences were found between the results in the conditions: 0Âș - 0Âș and 0Âș - 90Âș; 0Âș - 0Âș and 0Âș - 180Âș; -0Âș - 0Âș and 0Âș - 270Âș. CONCLUSION: The following sentence recognition thresholds in the noise, in sound field, were obtained for these signal-to-noise ratios: 0° - 0° = -7.56 dB; -0Âș - 90Âș = -11.11 dB; -0Âș - 180° = -9.75 dB; 0Âș - 270Âș = -10.43 dB. The better thresholds were obtained with the incidence angles of 0Âș - 90Âș and 0Âș - 270Âș, followed by the 0Âș - 180Âș condition, and, finally, by the 0Âș - 0Âș condition. The most unfavorable hearing condition was that in which the noise was in the same incidence angle of the speech, in front of the evaluated subject
Limiares de reconhecimento de sentenças no ruĂdo, em campo livre: valores de referĂȘncia para adultos normo-ouvintes Speech recognition thresholds in noisy areas: reference values for normal hearing adults
Nas clĂnicas de audiologia, as queixas de dificuldade de compreensĂŁo da fala em ambientes ruidosos sĂŁo freqĂŒentes, mesmo para indivĂduos normo-ouvintes. Assim, o audiologista deve nĂŁo sĂł identificar uma perda auditiva, mas tambĂ©m analisar a compreensĂŁo da fala, em condiçÔes de comunicação prĂłximas Ă s encontradas no cotidiano. OBJETIVO: Determinar o valor de referĂȘncia para os limiares de reconhecimento de sentenças no ruĂdo, em campo livre, para indivĂduos adultos normo-ouvintes. MATERIAL E MĂTODO: O experimento foi realizado nos anos de 2005 e 2006. Participaram da pesquisa 150 indivĂduos adultos normo-ouvintes, com idade entre 18 e 64 anos, avaliados em cabine acusticamente tratada. Realizou-se a avaliação a partir da aplicação do teste Listas de Sentenças em PortuguĂȘs. As listas de sentenças foram apresentadas em campo livre, na presença de um ruĂdo competitivo, na intensidade fixa de 65 dB A. O Ăąngulo de incidĂȘncia de ambos os estĂmulos foi de 0Âș- 0Âș azimute. RESULTADOS E CONCLUSĂO: Os limiares de reconhecimento de sentenças em campo-livre foram obtidos na relação sinal-ruĂdo de -8,14 dB A, sendo este o valor de referĂȘncia para indivĂduos normo-ouvintes.<br>In audiology clinics, complaints about difficulties in speech recognition in noise environments are frequent, even for normal-hearing individuals. Thus, the audiologist must not only identify a hearing loss, but also analyze speech recognition, under noisy conditions similar to those found in our daily lives. AIM: Determine the reference value for the recognition of phrases under noisy conditions, in the free field, for adult normal hearing patients. MATERIALS AND METHODS: This study was carried out in 2005 and 2006. We had 150 adult normal hearing individuals participating, with ages between 18 and 64 years, assessed in a sound-proof booth. We evaluation was based on lists of phrases in Portuguese. The phrases lists were presented in the free field, in the presence of a competitive noise, at the fixed intensity of 65 dB H. The incidence angle of both stimuli was 0Âș- 0Âș azimuth. RESULTS AND CONCLUSION: The phrases recognition thresholds in the free fields were obtained in the signal to noise ratio of -8.14 dB H, which is the reference value for normal hearing individuals