RESUMO
Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt[S{NN}]=17.4 GeV at midrapidity (2.3 less than or approximately equal eta{lab} less than or approximately equal 3.0) over the range 0.7 less than or approximately equal p{T} less than or approximately equal 3.5 GeV/c. The spectra are compared to pi{0} spectra measured in Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N{part} less than or approximately equal 300), the yield of pi{0}'s with p{T} greater than or approximately equal 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N{coll}), while for central Pb+Pb collisions with N{part}greater than or approximately equal 350, the pi{0} yield is suppressed.
RESUMO
Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100
RESUMO
The masking of speech by amplitude-modulated and unmodulated speech-spectrum noise has been evaluated by the measurement of monaural speech recognition in such noise on young and elderly subjects with normal-hearing and elderly hearing-impaired subjects with and without a hearing aid. Sinusoidal modulation with frequencies covering the range 2-100 Hz, as well as an irregular modulation generated by the sum of four sinusoids in random phase relation, was used. Modulation degrees were 100%, +/- 6 dB, and +/- 12 dB. Root mean-square sound pressure level was equal for modulated and unmodulated maskers. For the normal-hearing subjects, essentially all types of modulated noise provided some release of speech masking as compared to unmodulated noise. Sinusoidal modulation provided more release of masking than the irregular modulation. The release of masking increased with modulation depth. It is proposed that the number and duration of low-level intervals are essential factors for the degree of masking. The release of masking was found to reach a maximum at a modulation frequency between 10 and 20 Hz for sinusoidal modulation. For elderly hearing-impaired subjects, the release of masking obtained from amplitude modulation was consistently smaller than in the normal-hearing groups, presumably related to changes in auditory temporal resolution caused by the hearing loss. The average speech-to-noise ratio required for 30% correct speech recognition varied greatly between the groups: For young normal-hearing subjects it was -15 dB, for elderly normal-hearing it was -9 dB, for elderly hearing-impaired subjects in the unaided listening condition it was +2 dB and in the aided condition it was +3 dB. The results support the conclusion that within the methodological context of the study, age as well as sensorineural hearing loss, as such, influence speech recognition in noise more than what can be explained by the loss of audibility, according to the audiogram and the masking noise spectrum.
