LAE Frequency refers to the look ahead excursion frequency, and this is the active range for the excursion protection algorithm. As shown in Figure 5-13, the peak of the excursion of the speaker usually happens in low-frequency range, while the speaker excursion in high frequency range is very small. So the speaker excursion damage mostly occurs with large amplitude low frequency signals, and therefore the excursion protection algorithm do not take high frequency signal into considerations.

As shown by the orange dash line in Figure 5-14, LAE frequency is the cutoff frequency of the low pass filter which is applied to reduce high frequency signals, and then the signals is sent into the excursion protection algorithm for calculation and protections.

If the value of LAE frequency is too high, the algorithm active range can includes too much high-frequency signals, which can cause the protection behavior to be too active. On the contrary, if the value of LAE frequency is too low, the protection algorithm can miss too much low frequency signals, and can cause the speaker excursion to exceed the limits. Usually, the suggestion is to adjust this value as 1 to 3 times of the model fitting frequency range of the speaker (for example, in Figure 5-14, we set the LAE frequency to around 2000Hz, similar as the model fitting range).