Last of my "informational" posts for today - hopefully these are not too boring! This one about the "Audio Circle of Confusion" Drs. Toole and Olive talk so much about, which is a problem that Synthesis directly aims to address. Most of this information is from Sean Olive's blog post about this, which can be found here:
http://seanolive.blogspot.com/2009/10/audios-circle-of-confusion.html
A
most excellent read, for someone wanting to really take the time to fully understand this.
First off, here is a picture of the measured room response of 250 identical high quality reference monitors but placed in 164 different control rooms. Theoretically, all the measurements should be the same since the speakers are the same - but they are not. The differences are due to the room itself. And keep in mind that these are professional audio control rooms, with acoustic treatments, optimized room designs, etc:
All of this leads to the dreaded Audio Circle of Confusion:
Since mix engineers cannot rely upon their mix environments to be perfectly flat and accurate, how can they expect their mixes to be perfectly flat and accurate? And, since they are also evaluating their own setups based on mixes created in OTHER mix environments - which will have problems of their own - how can they trust the recordings created by others when they are using them to check their own systems and mixes?
This is exactly the kind of research Harman does - to try to equalize all of these elements out so that one room will "sound" like another. And this research is what has led to the creation of ARCOS, SFM, and other technologies (as well as speakers such as the M2, 708, etc). In addition, it was research into solving the bass issues - which is where most of the problems lie in the graphs above - that led to the multiple subwoofer solution that the engineers at Harman developed (referenced in depth in the Floyd Toole article I mentioned above - here it is again for ease of access:
http://www.audioholics.com/room-acoustics/history-of-multi-sub-sfm).
All of these things converge in Synthesis, and why a Synthesis system is used for final Blu-ray mastering in most cases.
One of the things that you find with extremely accurate speakers like those from Revel and JBL is that deficits in the original recording are laid bare. If the recording was mixed on bass heavy speakers (or in a bass heavy room), the recording engineer may have rolled off the bass in the recording to compensate. Now what we have is a "bass-shy" recording. Often just the opposite is true. As Sean Olive says, the recording itself becomes the "nuisance variable" in the equation. As I've stated elsewhere, IMO this is not an argument for less accurate speakers, it becomes an argument for better quality recordings.
So, by trying to solve this Circle of Confusion, Harman is working hard to take these variables out of the recording and mastering process so that we can all benefit. Good sounding recordings will sound best on the widest variety of speakers, but best on the most
accurate speakers.
Here is essentially the majority of Sean's article:
Audio’s “Circle of Confusion” is a term coined by Floyd Toole that describes the confusion that exists within the audio recording and reproduction chain due to the lack of a standardized, calibrated monitoring environment. Today, the circle of confusion remains the single largest obstacle in advancing the quality of audio recording and reproduction.
The circle of confusion is graphically illustrated in (the illustration above). Music recordings are made with (1) microphones that are selected, processed, and mixed by (2) listening through professional loudspeakers, which are designed by (3) listening to recordings, which are (1) made with microphones that are selected, processed, and mixed by (2) listening through professional monitors...... you get the idea. Both the creation of the art (the recording) and its reproduction (the loudspeakers and room) are trapped in an interdependent circular relationship where the quality of one is dependent on the quality of the other. Since the playback chain and room through which recordings are monitored are not standardized, the quality of recordings remains highly variable.
A random sampling of ones own music library will quickly confirm the variation in sound quality that exists among different music recordings. Apart from audible differences in dynamic range, spatial imagery, and noise and distortion, the spectral balance of recordings can vary dramatically in terms of their brightness and particularly, the quality and quantity of bass...
The most likely culprits are the loudspeakers and rooms through which the recording were made. While there are many excellent professional near-field monitors in the marketplace today, there are no industry guidelines or standards to ensure that they are used. The lack of meaningful, perceptually relevant loudspeaker specifications makes the excellent loudspeakers difficult to identify and separate from the truly mediocre ones. To make matters worse, some misguided recording engineers monitor and tweak their recordings through low-fidelity loudspeakers thinking that this represents what the average consumer will hear. Since loudspeakers can be mediocre in an infinite number of ways, this practice only guarantees that quality of the recording will be compromised when heard through good loudspeakers...
Another significant source of variation in the recording process stems from acoustical interactions between the loudspeaker and the listening room. Below 300-500 Hz, the placement of the loudspeaker-listener can cause >18 dB variations in the in-room response due to room resonances and placing the loudspeaker in proximity to a room boundary....Below 100 Hz, the in-room bass response can vary as much 25 dB among the different control rooms! You needn’t look any further than here to understand why the quality and quantity of bass is so variable among the recordings in your music library.
Loudspeaker manufacturers are also trapped in the circle of confusion since music recordings are used by listening panels, audio reviewers, and consumers to ultimately judge the sound quality of the loudspeaker. The problem is that distortions in the recording cannot be easily separated from those produced by the loudspeaker. For example, a recording that is too bright can make a dull loudspeaker sound good, and an accurate loudspeaker sound too bright...Through 25+ years of well-controlled loudspeaker listening tests, scientists have identified the important loudspeaker parameters related to good sound, which can be quantified in a set of acoustical measurement...By applying some statistics to these measurements, listeners’ loudspeaker preferences can be predicted...Good bass is essential to our enjoyment of music, which unfortunately is a frequency range where loudspeakers and rooms are most variable...Controlling the behavior of loudspeakers and rooms at low frequencies is essential to achieving a more consistent quality of audio recording and reproduction. Fortunately, there are technology solutions today that provide effective control of acoustical interactions between the loudspeaker and rooms...the key in breaking the circle of confusion lies in the hands of the professional audio industry where the art is created. A meaningful standard that defined the quality and calibration of the loudspeaker and room would improve the quality and consistency of recordings. The same standard could then be applied to the playback of the recording in the consumer’s home or automobile. Finally, consumers would be able to hear the music as the artist intended.