Expert Stuff: Google's Mike Cohen

How much computational power does a speech recognition system require?

It depends on when you mean. When we're actually doing recognition, at that moment the recognizer's running on a CPU, so on a CPU, we'll, in real time, do recognition. But in order to achieve the performance we get, in order to build these models, we may spend many, many decades of computer time to compute the language model for English as it works right now. So it evolves over time because we get more data, CPUs get faster and stuff like that, but just to train one language model for English we might use 230 billion, for example, words' worth of data, and that might take multiple decades of time if it was running on one CPU. But obviously, we'll apply thousands of CPUs to it so we can keep training these all the time.