Harman Kardon
In 1959, Harman Kardon marketed the Citation II, an early ultra wideband stereophonic tube amplifier. Designed by Stewart Hegeman, it featured 60 watts/channel output with a frequency response of 18-60,000 Hz at 20 watt output. The company promoted their philosophy of designing high fidelity sound using amplifiers that provided widest possible audio bandwidth. Although the human ear highest audible range is around 20,000 Hz, the full range of sound goes beyond that with harmonics and overtones that may be beyond the hearing range of the human ear. These harmonics interact with other frequencies to produce audible secondary sounds or interference. Harman Kardon promoted the design in audio magazines and product brochures.
Music-related memory
Absolute pitch (AP) is the ability to produce or recognize specific pitches without reference to an external standard. People boasting AP have internalized pitch references, and thus are able to maintain stable representations of pitch in long-term memory. AP is regarded as a rare and somewhat mysterious ability, occurring in as few as 1 in 10,000 people. A method commonly used to test for AP is as follows: subjects are first asked to close their eyes and imagine that a specific song is playing in their heads. Encouraged to start anywhere in the tune they like, subjects are then instructed to try to reproduce the tones of that song by singing, humming, or whistling. Productions made by the subject are then recorded on digital audio tape, which accurately preserves the pitches they sing avoiding the potential pitch and speed fluctuations of analog recording. Lastly, the subjects' productions are compared to the actual tones sung by the artists on the CDs. Errors are measured in semitone deviations from the correct pitch. This test, however, does not determine whether or not the subject has true absolute pitch, but rather is a test of implicit absolute pitch. Where true absolute pitch is concerned, Deutsch and colleagues have shown that music conservatory students who are speakers of tone languages have a far higher prevalence of absolute pitch than do speakers of nontone languages such as English. For a test of absolute pitch see the Absolute Pitch Test developed by Deutsch and colleagues at the University of California San Diego.