US Patent 10415601 Blower noise suppressor

A blower assembly including a housing, a blower within the housing, and a cut-off that is within the housing downstream of the blower with respect to direction of airflow generated by the blower. Openings are defined by the cut-off. The openings are configured to permit airflow generated by the blower to pass through the openings and to a discharge outlet of the blower assembly. The openings are further configured to reduce blower frequency tone generated as airflow passes across the cut-off.