Letter (Astounding, April 1946): Bats Can Be Heard to Squeak—But the 60,000 Cycle Squeaks—the Really Important Part of Their Squeaking—Is Inaudible. Same with Television. Some of It Can Be Heard, But Only the Small Fraction Between 50 and 15,000 Cycles. The Part from 15,000 to 5,000,000 Cycles Is LOst.

From Author Wars - https://authorwars.com/books/letter-astounding-april-1946-bats-can-be-heard-to-squeak--but-the-60000-cycle-squeaks--the-really-im-2098038.html

Overview:

Title: Letter (Astounding, April 1946): Bats Can Be Heard to Squeak—But the 60,000 Cycle Squeaks—the Really Important Part of Their Squeaking—Is Inaudible. Same with Television. Some of It Can Be Heard, But Only the Small Fraction Between 50 and 15,000 Cycles. The Part from 15,000 to 5,000,000 Cycles Is LOst.
Author: William M. Danner
Year: 1946
Type: Essays

Editions/Publications:

Unknown. Astounding Science Fiction, April 1946 (Unknown, William M. Danner, Street & Smith Publications, Inc., $0.25, 180 pages, digest, MAGAZINE)

This text has been adapted from the Letter (Astounding, April 1946): Bats Can Be Heard to Squeak—But the 60,000 Cycle Squeaks—the Really Important Part of Their Squeaking—Is Inaudible. Same with Television. Some of It Can Be Heard, But Only the Small Fraction Between 50 and 15,000 Cycles. The Part from 15,000 to 5,000,000 Cycles Is LOst. entry at the Internet Speculative Fiction Database and is available under a Creative Commons License. The ISFDB does not endorse or sponsor this use.