主题：[原创]关于MAXXBASS和差频的疑问

PHENOMENON OF THE MISSING FUNDAMENTAL

The Phenomenon of the Missing Fundamental was discovered initially by pipe organ builders during the 1700s. The large cathedrals during the Middle Ages had huge pipe organs that with pipes up to forty feel long to generate the really low frequencies that helped draw crowds of people to these church services to feel the bass as well as hear the spiritual message Some composers of pipe organ music found that they could “trick: the listener into hearing low bass tones that weren’t really there if the played a certain combination of notes that were higher than the low tone or “fundamental” that they wanted to be heard. For example, if they wanted the listener to hear a low C then they could play a C an octave higher and a G above that, and the low C would magically appear in the listener’ head.

The Phenomenon of the Missing Fundamental has also been studied and proven by many distinguished audio scientists such as Helmholtz, who discovered how vented port and vents operate. The perceived pitch of a combination of tones spaced equally in frequency is usually not that of the mean frequency, but rather that of the constant difference frequency. The constant difference frequency is the missing fundamental.

MAXXBASS

Meir Shashoua, the CTO of Waves, developed a theory on how the Phenomenon of the Missing Fundamental could be applied to loudspeaker reproduction limitations. Waves, the leader in audio signal processing ‘plug-ins’ tools for the professional audio market, leveraged its world leadership psychoacoustics to improve and sharpen this psychoacoustic effect. This technology, called MaxxBass was patented (U.S. Patent #5,930,373). MaxxBass has also been patented in Japan.

Waves MaxxBass and second generation Renaissance Bass plug-in utilize this technology and have become a standard tool over the past few years in creation of much of the world’s most popular music. These software tools are used to improve bass punch on bass limited systems. This is important on popular music may be played on everything from a dance floors with subwoofer arrays to small portable systems with severely limited bass capability. An example of the music mixed with this MaxxBass technology is “Lady Marmalade” by Christina Aguilera

The MaxxBass is even more effective when implemented directly in consumer audio reproduction systems, since the MaxxBass can be ‘tuned’ to the specific loudspeaker parameters improving performance on any audio bass content. This is now possible due to a cost-effective MX3000AS ASIC (Application Specific Integrated Circuit) as well as DSP software licensing from Waves.

Another significant advantage of implementing MaxxBass in consumer audio equipment is that this solution, unlike the professional audio editing tools, includes a high pass filter (HPF) removing the original bass frequencies that can not be reproduced by the loudspeaker. These frequencies are no longer needed since MaxxBass reproduces these through psychoacoustics. The HPF eliminates damaging speaker excursion, unnecessary power consumption and undesirable intermodulation distortion in the loudspeaker.

Boosting the low-frequency performance of a speaker by 1-1.5 octaves normally requires both increased headroom in the amplifier and increased excursion in the driver, plus extra Bl to maintain control at high excursion, all of which involve substantially more cost than implementing MaxxBass. MaxxBass is a powerful and cost-effective technology to audio system designers to improve bass response. It has widespread applications across audio applications including automotive, home audio, television, portable and personal audio.