What award was won in the best sound category for the exorcist before 1998?
CREATE TABLE "feature_film" (
  "year" real,
  "award" text,
  "category" text,
  "type" text,
  "title" text
);
SELECT "award" FROM "feature_film" WHERE "year"<1998 AND "type"='won' AND "category"='best sound' AND "title"='the exorcist';