Temporal masking-level differences: the effect of mask duration.
Psychometric functions were obatained for the interaural conditions NoSo and NoSπ in both forward and backward masking using masks of different durations. In addition, data were collected for the Sm, Sπ and So conditions without an external mask. The slope parameter k and the signal level required for 76% correct detection were computed with a least‐squares technique. The results were that both temporal masking and temporal masking‐level differences (MLDs) increased monotonically with longer mask durations. This mask‐duration effect was more pronounced for forward masking than for backward masking. Without an external mask, the signal was about 3 dB more detectable in the So configuration than in the Sπ configuration, and it was about 4 dB more detectabe in the Sπ configuration than in the Sm configuration. The psychometric functions were generally steeper for the NoSπ condition than for the NoSo condition in forward masking, but not in backward masking. They were also steeper for the Sπ condition than fo...
Comparison of Binaural Release from Forward Masking in Animals and Humans. Electrophysiological Studies
Evoked potentials in the inferior colliculus and auditory areas of the cortex were studied in anesthetized guinea pigs and long-latency auditory evoked potentials (LAEP) were studied in waking humans using sequential binaural presentation of pairs of clicks – the masker and the masked signal – with a variable interval between them, to provide the conditions needed for the psychophysical phenomenon of direct forward masking. Introduction of phase differences between the masker and the masked signal led to decreases in suppression of responses to the masked signal and to faster recovery of the reaction types recorded. The greatest relative differences between response magnitudes to antiphase and synphase masked signals were seen at the beginning of the recovery process, and were 1.6, 1.5, and 1.4 respectively for responses from the inferior colliculus, auditory area of the cortex, and LAEP at stimulus intensities of 50–65 dB sound pressure level, differences subsequently decreasing to zero. There was a positive correlation between this measure and the stimulus intensity. The greatest differences between the time at which the recovery process ended for responses to antiphase and synphase masked signals were 4, 250, and about 2000 msec respectively for the inferior colliculus, auditory area of the cortex, and LAEP.
Actuating Principle of Online Automatic Balancer with Counter Weight Driven by Magnetic Force
Kinematic precept of mass block in automatic balancer is proposed following the principle of online automatic dynamic balancing.By combination of electromagnet and permanent magnet,the magnetic circuit of the balancer with ring coil and rare earth permanent magnet is designed.Actuating process of the balancer is discussed and then a step drive voltage waveform is defined.For the high-speed grinding motorized spindle 170MD12Y16,the mechanical structure and dimensions of the balancer are schemed out.The electromagnetic simulations for the designed balancer are conducted and the better coil ampere-turns and reluctance adjusting ring thickness are then determined.The validity of simulation results is verified by a balancer driving experiment and the desired voltage value and its duration time are also determined.the designed balancer has a stable operation process without out-of-step and fluctuation around balanced position when the ampere-turns are considered as 1 kA,the reluctance adjusting ring thickness 0.2 mm,the driving voltage 12.4 V and the voltage duration time 120 ms.