audio_column_ = new Audio_column (*m);
announce_element (Audio_element_info (audio_column_, 0));
precomputed_recurse_over_translators (context (), START_TRANSLATION_TIMESTEP, UP);
audio_column_ = new Audio_column (*m);
announce_element (Audio_element_info (audio_column_, 0));
precomputed_recurse_over_translators (context (), START_TRANSLATION_TIMESTEP, UP);