| 1936 MORAN Acoustic Signaling Device Patent |
| 1931 BODINE ALFRED Acoustic Device Patent Print |
| 1930 HARRISON HENRY Acoustic Device Patent Print |
| 1937 FRITZ Acoustic Warning Device Patent Print |
| 1929 GOODRUM CHARLES Acoustic Device Patent |
| 1932 CLIFFORD JOHNSON Acoustic Device Patent |
| 1960 ALBERT Acoustic Alarm Device Patent Print |
| 1935 BLATTNER DAVID Acoustic Device Patent Print |
| 1929 WESTERN ELECTRIC CO Acoustic Device Patent |
| 1948 EDMOND BRUCE Acoustic Device Patent Print |
| 1945 AGNE Acoustic Alarm Device Patent Print Art |
| 1931 DICTAPHONE CORP Acoustic Device Patent |
| 1941 MOULDING THOMAS Acoustic Device Patent |
| 1954 LEVY SIDNEY Acoustic Device Patent Print |
| 1933 BEDELL EUAL Acoustic Device Patent Print |
| 1920 THOMAS GEORGE Acoustic Device Patent Print |
| 1928 HOOD Acoustic Signaling Device Patent Print |
| 1932 SMYTHE EDWIN Acoustic Device Patent Print |
| 1937 BOSCH ROBERT Acoustic Warning Device Patent |
| 1925 HEINRICH Acoustic Signaling Device Patent |
| 1920 WESTERN ELECTRIC CO Acoustic Device Patent |
| 1929 LUM GEORGE Acoustic Device Patent Print Art |