Spontaneous Symmetry Breaking and the Renormalization of the Chern-Simons Term

We calculate the one-loop perturbative correction to the coefficient of the \cs term in non-abelian gauge theory in the presence of Higgs fields, with a variety of symmetry-breaking structures. In the case of a residual $U(1)$ symmetry, radiative corrections do not change the coefficient of the \cs term. In the case of an unbroken non-abelian subgroup, the coefficient of the relevant \cs term (suitably normalized) attains an integral correction, as required for consistency of the quantum theory. Interestingly, this coefficient arises purely from the unbroken non-abelian sector in question; the orthogonal sector makes no contribution. This implies that the coefficient of the \cs term is a discontinuous function over the phase diagram of the theory.Comment: Version to be published in Phys Lett B., minor additional change

Effect of speaker age on speech recognition and perceived listening effort in older adults with hearing loss

Published online January 2012Purpose: Older adults exhibit difficulty understanding speech that has been experimentally degraded. Age-related changes to the speech mechanism lead to natural degradations in signal quality. We tested the hypothesis that older adults with hearing loss would exhibit declines in speech recognition when listening to the speech of older adults, compared with the speech of younger adults, and would report greater amounts of listening effort in this task. Methods: Nineteen individuals with age-related hearing loss completed speech recognition and listening effort scaling tasks. Both were conducted in quiet, when listening to high and low predictability phrases produced by younger and older speakers respectively. Results: No significant difference in speech recognition existed when stimuli were derived from younger or older speakers. However, perceived effort was significantly higher when listening to speech from older adults, as compared to younger adults. Conclusions: For older individuals with hearing loss, natural degradations in signal quality may require greater listening effort. However, they do not interfere with speech recognition – at least in quiet. Follow-up investigation of the effect of speaker age on speech recognition and listening effort under more challenging noise conditions appears warranted