The QSound Approach

QSound inventors Danny Lowe and John Lees’ original research was based on phenomena experienced in the recording studio as a result of experimentation with multiple micro- phones. Eventually they were able to achieve the impression of sound apparently originating from thin air, far beyond the normal limitations of the stereo sound stage. After initial analysis of audio tape recordings, a series of experiments was conducted using a Hewlett Packard signal generator and an Eventide Clockworks Precision Delay. Though the latter was hardly a laboratory-grade instrument, the two men were able to demonstrate the possibilities well enough to raise interest and research capital.

» Armed with the results of this crucial early work, Lowe and Lees assembled a team of scientists and audio professionals.

» Software tools for sound analysis and modeling, test signal generation and statistical data analysis were custom developed in house, exploiting the newly available power of purpose-designed DSP (digital signal processor) IC’s and desktop computers.

» QSound entered into an intense research phase, modeling sound wave propagation from loudspeakers, extrapolating promising theories for further exploration.

» Human listeners were presented with carefully designed test signals which had been passed through the initial process algorithms and delivered through stereo speakers in several controlled environments.

» Listener responses were captured using a custom data entry system consist- ing of multiple hand-held electronic keypads and a central data collector.

» As the system operators adjusted various characteristics of the test signals and process algorithms, analysis of the data was performed using a combi- nation of software and skilled human judgement.

» As trends emerged, the processes were refined, retuned, retested and fur- ther refined in an iterative procedure taking place over many months. A key element in this task was the participation of team members having a background in the professional audio recording industry.

» In all, over 550,000 listening tests were performed, using a variety of subjects in order to produce averaged results leading to algorithms effective for virtually any listener.

In short, rather than take a legitimate binaural model, and imperfectly and inefficiently adapt it to speakers through additional crosstalk cancellation, the QSound team concentrated directly on the target environment: the human percept of sound location as presented through stereo speakers.

The result was arguably the world’s most natural-sounding, effective, and inherently efficient positional 3D audio algorithms for stereo speakers. In practical consumer applications such as desktop computers and mobile devices, the efficiency advantage over the combination of binaural synthesis with crosstalk cancellation should not be underestimated, as it has a direct impact on system compute and memory requirements, and therefore, product cost.

This initial algorithm development became the basis of the first commercial applications developed by QSound, the core of the QSystem hardware processor that was applied to the production of professional music releases and movie soundtracks, and became the foundation for what was to become the most complete suite of 3D algorithms available.

QSound Advantages

Better Audio Performance
All QSound 3D audio processes are fine-tuned by skilled audio engineers for the most natural, pleasing sound experience possible. QSound 3D audio is characterized by broadband imaging with superior focus and correct frequency balance, worthy of professional audio applications.

More Robust Algorithms
QSound’s speaker-targeted 3D processes are much more forgiving in the area of speaker/ listener geometry than crosstalk cancelation systems. This means a much larger effective listening area and a great deal more flexibility in the placement of the speakers. An additional benefit of the extensive acoustic design effort underlying QSound algo- rithms is their robustness in band-limited situations such as handheld applications. Though high frequencies may be limited by low sampling rates, and small speakers may limit bass response, QSound algorithms continue to create excellent effects. Even so, the challenges of hand-held device speaker geometry, characterized by extreme- ly narrow speaker separation and a variety of speaker orientations (front, rear, and side- firing speakers), call for special measures. QSound can supply OEM's with the ability to test and tune algorithms for maximum effectivness on portable platforms.

Higher Efficiency
The efficiency of QSound’s speaker algorithms is first due to the fundamental method of their derivation as described in the previous section. The approach taken by competing speaker 3D processes, i.e. the application of crosstalk cancelation to binaural synthesis, is by nature inefficient. Furthermore, the efficiency of all QSound 3D algorithms is due to a thorough under- standing of the relative importance of various independent factors contributing to the net result. This has made it possible to derive from a ‘gold standard’ algorithm a family of lower-overhead versions each exhibiting the most effective possible performance within their respective budgets. Finally, QSound designers have a reputation for implementing a given algorithm by the most efficient method. Signal processing routines are written in hand-tuned assembly code by specialists adept at squeezing maximum value from each machine cycle.

QSound Features

Q3D
Complete DirectSound, DirectSound3D, A3D and I3DL2-compatible digital audio mix engine with advanced 3D positioning, including 2D to 3D remix for non 3D games, for headphones and 2 to 7.1 channel speaker systems.

Q3D Block Diagram

QEM
EAX and EAX2.0-compatible acoustic environment simulation, for headphones and 2 to 7.1 channel speaker systems. QSound Acoustic Environment Modeling includes Audotorium, Bathroom, Church, Concert Hall, Forest, Hall, Hangar, Mountains, Psychotic, Quarry, Sewerpipe, Stadium, Theater, Underwater.

VIA Vinyl Audio QSound QEM Control Panel

QXpander
Mono to 3D and stereo to 3D stereo sound stage synthesis and enhancement for headphones and stereo speakers.

QXpander Block Diagram

VIA Vinyl Audio QSound QXpander Control Panel

QEqualizer
8-band equalizer, it can be adjusted at 31Hz, 62Hz, 125Hz, 250Hz, 1KHz, 2KHz, 4KHz, 8KHz and 16KHz.

VIA Vinyl Audio QSound QEqualizer Control Panel

QVerb
Reverberation optimized for music and movies, for all configurations. Many of presets are included, including MP3 Music, Neutral, Techno, Jazz, Rock, PoP, and Classic.

VIA Vinyl Audio QSound QVerb Control Panel

Speaker Setup
Input Gain adjustment for Speakers and Headphones. The Speaker test is also included, so you can test the speakers at various locations manually or automatically.

VIA Vinyl Audio QSound Speaker Setup Control Panel

For more information, please go to www.qsound.com.

Ressourcen

	QSound Home Page » www.qsound.com
	QSound Audio Demo Rockstar » Download Audio! (wma / 1.3MB)
	QSound Audio Demo Tour of London » Download Audio! (mp3 / 2.9MB)