Specifically, we downsampled our data using the following procedure: First, we discarded all word/function pairs with tokens from fewer than four different speakers; second, for each of the remaining word/function pairs, we discarded tokens (at random) from speakers who contributed more than 25% of its tokens.
the resulting data set meets two conditions: For each word/ function pair, (a) tokens come from at least four different speakers, and (b) no single speaker contributes more than 25% of the tokens.