A method for listening to ultrasonic animal sound signals comprises: obtaining a plurality of input samples at an input sample rate, the plurality of input samples including at least one sequence of samples corresponding to an instance of an intermittently occurring animal sound signal; receiving a frame including at least two of the plurality of input samples; selecting a fraction of the samples as output samples, the fraction of the samples including a sample containing the at least one sequence of samples corresponding to an instance of an intermittently occurring animal sound signal; and transmitting the output samples at an output sample rate slower than the input sample rate.