PURPOSE: To demonstrate how a sinusoidal tone can be masked when its frequency is in the vicinity of narrow-band noise.

DESCRIPTION: Narrow-band noise is produced with its frequency centered near A=440Hz. Playing a scale from the bottom to the top of the synthesizer keyboard, one easily hears notes at frequencies below and above that of the narrow-band noise. In the region of the noise, the scale tones are masked, and cannot be heard.

SUGGESTIONS: THIS SYNTHESIZER HAS BECOME UNRELIABLE DUE TO AGE OVER THE YEARS SINCE 1975 WHEN WE OBTAINED IT, AND IS NO LONGER RECOMMENDED AS A RELIABLE DEMONSTRATION.

REFERENCES: (PIRA unknown.)

EQUIPMENT: ARP synthesizer set to accompanying patch sheet.

SETUP TIME: 5 min.