The first low frequency audio filter.?

2 ⤊

Can anyone provide a brief description and date of the first low frequency filter. It filtered out background noise below 500Hz.

2007-04-05 21:13:13 · 2 answers · asked by Caretaker 7 in Education & Reference ➔ Trivia

The limestone seats that are built within the Greek amphitheatre at Epidaurus, circa 4th century B.C.

2007-04-05 21:17:49 · answer #1 · answered by Jim M 2 · 2⤊ 0⤋

megaphone

2016-05-18 03:22:21 · answer #2 · answered by ? 3 · 0⤊ 0⤋