15. The non-transitory computer storage medium of claim 14 , wherein the operations further comprise: determining a context associated with the spoken query term; and selecting a subset of the past search queries that include contexts which are similar to the context of the spoken query term, wherein determining, for each n-gram, a frequency with which the n-gram occurs in the past search queries further comprises determining, for each n-gram, a frequency with which the n-gram occurs in the past search queries that are members of the subset only.
15. The non-transitory computer storage medium of claim 14 , wherein the operations further comprise: determining a context associated with the spoken query term; and selecting a subset of the past search queries that include contexts which are similar to the context of the spoken query term, wherein determining, for each n-gram, a frequency with which the n-gram occurs in the past search queries further comprises determining, for each n-gram, a frequency with which the n-gram occurs in the past search queries that are members of the subset only. 18. The non-transitory computer storage medium of claim 15 , wherein: determining a context associated with the spoken query term further comprises determining that a device used by the user to enter the spoken query term was docked or holstered when the user spoke the spoken query terms; and selecting a subset of the past search queries that include contexts which are similar to the context of the spoken query term further comprises selecting a subset of the past search queries that were submitted by the user when a device used by the user to enter the past search queries was docked or holstered when the user entered the past search queries.