This is an analysis of the neural mechanisms of sound avoidance responses triggered by the Mauthner system in fish. The following progress has been made. (1) Behavioral experiments show that goldfish turn away from sound sources predicted by our XNOR version of the phase model: the fish avoids P+/A+ and P-/A- (for impulse sounds in the near field, where P+ = positive pressure, A+ = particle acceleration toward the side of the activated Mauthner cell). (2) The Mauthner cell is broadly tuned to P+ and P- in the range of 0.1-2KHz, and equally is sensitive to A+ and A- at 0.1 KHz at about 0.1 m/sec(2). We have as yet seen no preferential Mauthner responsiveness to combinations of P and A; that is P+/A+, an ON combination, is not faster or larger than P+/A-, an OFF combination. If so, then the PHP cells must be performing a major part of the neural analysis. (3) The most recent version of our neurocomputational model predicts known Mauthner network dynamics when the PHP cells serve as OR gates; as previously shown, the PHP cells modulate Mauthner threshold to particular stimulus amplitudes and our model shows they can simultaneously allow Mauthner to discriminate left from right sound sources.