Spatial Attributes

The specific spatial attributes that we are investigating are "width of the source ensemble," "extent of the reverberant field," and "extent of immersion." We define the source ensemble width as how far spread the sources, or instruments, in a song are perceived on the horizontal plane. In other words, if one can imagine a group of instrumentalists performing on a stage, a performance across the full extent of the stage would denote a large source ensemble width. If the instrumentalists sounded as if they were clustered in one location on the stage, the source ensemble width would be small.

The extent of reverberation is the perceived size and type of room that the instrumentalists are performing in. A song may sound as if it has been recorded in a large, cavernous environment; or it may sound as if it was performed in a small, intimate space. Sometimes different instruments within a single song can be perceived as occupying spaces of varying sizes and types. We ask our participants to consider the song segment as a whole and give us their impression of the overall extent of reverberation.

Finally, the extent of immersion that a song gives a listener is a general way of describing whether a listener feels surrounded by what he or she is hearing. If one can imagine that he or she is in the center of a performance and that the musical sound is enveloping, then we can say that it is immersive. Conversely, if the music sounds as if it is arriving from a focused area in front of or to the side of the listener, it is not immersive.

What Will be Done With the Data?

The data you provide will help us to find whether there are consistencies in the way humans hear these specific spatial attributes in recorded music. If so, then we will apply signal processing and analysis techniques to the digital audio clips. We will attempt to model these particular spatial attributes in recorded music and define an objective means of measuring them.

Why is This Research Important?

This research is important because it hasn't been done before! There have been numerous analyses performed of and objective measurements proposed for how humans perceive spaciousness in natural acoustics. Additionally, there have been a number of studies in which human subjects have been asked to rate their perception of spaciousness for reproducing systems, such as 5.1 surround. However, a critical model of the digital signal attributes that may carry these percepts has not been proposed. It is important to understand how humans perceive recorded music so that music performers, producers, technologists, and consumers can make more informed decisions about this fascinating cultural, artistic, and technological medium.