SOUND CAMERA.

Auckland Star, Volume LXVI, Issue 307, 28 December 1935, Page 10

SOUND CAMERA.

SPEED CHIEF FEATURE.

TONE QUALITY "PICTURES."

(From Our Own Correspondent.)

SAN FRANCISCO, December 4

The construction of an electric sound "camera" that reduces from days' to seconds the time needed to make a picture record of tone quality was an-, nounced in Cambridge, Massachusetts by Harry H. Hall, instructor in physics at Harvard University. The machine was built at the Cruft Laboratory of Electric Communication Engineering.

Through these tone pictures the sounds of musical instruments can be studied and minute differences in tone between fine and ordinary instruments can be discovered and scientifically analysed. By using the new instrument scientists can also obtain accurate and detailed records of speech sounds and other noises. The apparatus makes a picture of the relative loudness in all its parts, including the fundamental pitch, the overtones and incidental sounds, such as the scratching of a violin bow. It records sounds within the range of 50 to 10,000 cycles. The limit of human hearing is ordinarily fixed between low pitches of about 20 cycles and high squeaks of 15,000 or 20,000 cycles.

To the scientist the chief advantage of the new instrument is its speed.' In 3.78 seconds a complete picture- of a. sound can be obtained. This penmits analysing of tones, such as those of the human voice, which can remain steady for* a very short period. Under older systems such a record could be obtained only after several days.