Before going further, we should perhaps cast a glance at all those systems of communication in which speech plays no part. ... The whistle of a policeman or referee, the siren of an ambulance or fire engine, the bell at your door or in the classroom, all convey messages as (5) as though they were spoken.
――岐阜大学 前期日程/地域科・教育学部(2月25日実施)――2005年