AudioEngine™

AudioEngine™represents the latest generation of sound field control technologies, and is the results of Yamaha's many years of experience in this domain.

• Total acoustics correction:Acoustic total-linear EQ
• Surround sound reproduction:Spacious sound 3D
• Audio bandwidth extension:Harmonics enhancer Extended

These processing technologies are all intended to reproduce audio materials as faithfully as possible—listeners hear what they would have heard live when the material was recorded. This design philosophy extends all the way down to the hardware designs of our devices. Furthermore, AudioEngine™ continues to evolve as new technologies for more faithful, high-definition sound reproduction are found and implemented.

The YDA174 and YSS952 are two devices that incorporate AudioEngine™ technology.

Acoustic total-linear EQ (or AEQ) is an acoustic correction technology from Yamaha, that has been built based on many years experience in acoustics design for concert halls around the world.

Such “phase correcting” digital signal processing aims to correct both frequency and phase transfer function errors that occur during the recording and reproduction process.

By correcting the phase characteristics in the time domain, as well as correcting the frequency characteristics, Total Linear Phase Acoustics Correction gives a better sense of the location of a sound source, in addition to more faithful sound reproductions. These in turn give a more realistic sense of sound presence than other technologies have been able to achieve thus far.

Because the loudspeakers in a TV cabinet typically do not face the listener directly, the sound coming from these products is rarely controlled. Accordingly, products such as flat-panel TVs are likely to have a muffled sound, as the high frequency range signals are attenuated further than lower frequencies.

Since the sound takes complex paths within the speaker cabinet, reflection and diffraction occur and the resulting uneven sound gives rise to distortion.

Spacious sound 3D (or S3D) processing enhances the perception of sound fields to provide a realistic, more comfortable listening experience regardless of the position of the listener. It is the end result of many years of experience designing sound fields for concert halls around the world. S3D adds a sense of depth to the stereophonic sound space using a technique based on virtual sound sources optimized for human auditory perceptions.

Yamaha have measured reverberation characteristics in concert halls and theaters around the world, and have recorded data for the acoustic space characteristics of these venues in a database.

S3D draws on this vast amount of real acoustic data to achieve a convincing listening experience that gives listeners the sensation of being at these venues by adding their characteristic surround sound components when expanding the perceived sound field.

S3D is also capable of increasing the perceived separation between the loudspeakers to give the sensation of a larger space. The real distance between the speakers of the product is taken into account when adjusting the phase manipulation processing.

Harmonics Enhancer Extended (or HXT) enhances both treble and bass ranges by reproducing harmonics to achieve an improved perceived sense of high fidelity. This, along with Acoustic total-linear EQ, makes the most out of even the physically restricted dimensions of today's compact sound equipment cabinets.

The deterioration in the sound quality of contemporary equipment is due to the acoustic design of their cabinets. Despite being the most important component in sound reproduction, loudspeakers suffer most as products become thinner and more compact. Many designs fail to cope with the physical restraints—for example, thinner cabinets restrict the speaker cone movement, preventing them from achieving their full stroke and resulting in sub-optimal output power and poorer bass sound reproduction.

Yamaha has taken particular note of the “missing fundamentals”—missing bass frequencies present in any tone. This approach involves making use of an illusion of the brain. The brain does not recognize the pitch of a tone from its bass frequency alone, but also from the harmonic ratios which are component parts of the tone. For this reason, it is claimed, even when the bass frequency is not sounded, the human brain can still recognize the bass.

HXT is a technology which makes use of this phenomenon to enable the listener’s brain to recognize a sound, just as if the low-frequency sound is actually being played. It does this by extracting the bass frequencies that the speakers cannot play and accentuating the sound’s harmonic components. HXT also takes into account the fact that the magnitude and ratios of the added harmonics will affect the sound quality, and its adept combination of odd and even harmonics serves provides an overall sound that is a faithful reproduction of the original.

Some popular compressed audio formats such as MP3 or AAC are based on frequency-domain compression, and give bass range frequency bands lower priority in data bit allocation than mid- or high-range components during the compression process. Although low bit-rate compressed audio materials thus have less bass components, HXT can restore those components that have been neglected in compression, and along with its ability to restore high-range components omitted in some forms of audio compression, give the reproduced sound the vigor of the original.