Given the task definition and input, reply with output. In this task you will be given a process, and a question. The process contains a sequence of steps that happen in order. The question asks about the effect of a certain event on another event. If the first event has a positive effect on the second event, answer with "for", if it has a negative effect, answer with "against". If there's no causal relationship between the two, answer with "none".

Process:  -Bats and other animals produce a high-pitched tone -The sound travels in waves, as sound does -The sound 'bounces' off of a nearby object -The sound wave returns to the bat -The bat hears the echoed sound -Folds in the bat's ear and adaptations in the bat's brain enable it to determine the size, shape, and position of the other object via the properties of the returned sound waves -Other animals use echolocation in generally similar ways -
 Question: What is the effect of there are many objects on the bat will not be able to navigate the area.?

for