Recreating Sound Fields On the Basis of Real-World Data
Every room, club or concert hall has unique acoustic properties which influence the music we hear in them. The size and shape of the room, the materials used in the construction of the ceiling, walls, and floor, furnishings, and even the number of people in the room all determine the sound that reaches our ears. Echoes, reflections, and reverberations created by the room itself are all a part of the sound we hear. These reflections enable us to perceive where the instrument is in the room, and how far away, even when blindfolded. our ears and brain are naturally analyzing the volume, timing, and direction of the reflections. These information allow us to perceive where the player is situated, and even what size hall we are in. These spatial dynamics are what give music the aesthetically pleasing elements of tone, depth, and timbre that drive the emotional response of the listener.	Yamaha HiFi DSP brings the concert hall into the comfort of your home.

Analyzing the Sound Field

The sound we hear in a concert hall or club - or in any environment, for that matter - can be analyzed in terms of the "direct sound" and its multiple discrete reflections.

The direct sound of a violin solo in the concert hall is the sound of the violin unreflected off any surfaces. Additionally, there are multiple "early reflections" of the same sound which reach us after reflecting off surfaces in the room. More specifically, early reflections are those discrete echoes which reach us within a time span of 50 to 80 milliseconds after the arrival of the direct sound.

Then there are various subsequent reverberations, compound reflections from several surfaces throughout the room that create a continuous "wash of sound". The early reflections contain the auditory cues that give us directional information, allowing us to perceive the actual size and shape of the room.

If the early reflections can be accurately measured, and accurately reproduced with direction, level and timing information intact, then we can reproduce the auditory cues needed to recreate the spatial characteristics - the sound field - of any performance environment. This is exactly what Yamaha has done in developing the HiFi DSP.

	Early reflections of the direct sound provide the auditory cues on timing, level and direction that tell us the size, shape and acoustic nature of the environment.

Capturing Early Reflections Response Patterns

Using an extremely precise measurement technique - The Closely Located Four Point Microphone Method - developed by the Acoustics Engineering Laboratory of Waseda University, a leading Japanese university, Yamaha engineers and acoustic engineering specialists have succeeded in accurately measuring the early reflection response patterns in any performing environment.

The Closely Located Four Point Microphone Method is an excellent way to grasp spatial information about a room by measuring impulse responses from four closely positioned but slightly different points. This enables us to determine the direct source of any sound in prescribed space. The impulse data is then analyzed by computer to determine the virtual image source of each reflection.

With this directional, timing, and level information on early reflections, it is possible to digitally recreate the multiple early reflection response patterns of any sound field which has been analyzed.

Since the information from these early reflections is what tells our ear and brain the size, shape and physical characteristics of a sound field, it is possible to recreate the precise acoustic personality of any given performing environment with accuracy and realism.

The Result is Realistic Sound

With Yamaha Digital Sound Field Processing it is thus possible to recreate the actual sound of a venue. When one of the "Jazz Club" modes is selected, for instance, you are listening to the acoustical characteristics of a real jazz club. You can select from multiple clubs, for instance: Village Gate Club or the Cellar Club; both in New York City. Select "Stadium" and enjoy your favorite rock group in Anaheim Stadium. Yamaha Digital Sound Field Processing makes it possible to hear your favorite artist perform in the venue of your choice.