1. A system comprising: a computer-readable memory storing executable instructions; and one or more processors in communication with the computer-readable memory, wherein the one or more processors are programmed by the executable instructions to at least: obtain a model for detecting a keyword in an audio sample and a detection threshold corresponding to the model, wherein a detection score greater than the detection threshold indicates that the keyword is present in the audio sample, and wherein the detection score is computed using the audio sample and the model; determine an estimated false rejection rate, wherein the false rejection rate comprises an estimate of a probability that a received audio sample comprises the keyword and that a detection score for the received audio sample is less than the detection threshold; obtain a transmit threshold for determining whether to transmit audio samples, wherein a detection score greater than the transmit threshold indicates that an audio sample for which the detection score is computed is to be transmitted to a server computing device, and wherein the transmit threshold is less than the detection threshold; transmit the model, the detection threshold, and the transmit threshold to a client computing device, wherein the client computing device receives a first audio sample, computes a first detection score using the first audio sample and the model, determines that the first detection score is greater than the transmit threshold, and transmits the first audio sample to the server computing device based at least on the first detection score being greater than the transmit threshold; obtain, from the client computing device, a plurality of audio samples, wherein each of the audio samples is associated with a detection score; determine a false rejection rate using at least a portion of the plurality of audio samples; determine, based at least in part on the determined false rejection rate, at least one of a second model or a second detection threshold; and transmit at least one of the second model or the second detection threshold to the client computing device.