BBC L1 lip microphone, 1937-1960
1937-1960
1937-1960
2008
1951-1953
2000-2006
1946-1948
1948
1950-1955
1923
1923
1951
2001
circa 1930s
1970-1980
1935-36
1977
1985-1995
2009
circa 2000
2004
1977-2008
1936
2008
1987
1952
1993
2013
1926-1929
circa 1954
1970
circa 1931
1971
1927-1933