Deeper Reading 4

The line source and the ear-brain system.

Our human ear-brain system is incredibly complex and only barely understood. Scientists have discovered how we perceive sound’s depth, azimuth, bearing and the size of the space in which the sound occurs.

We hear space in several ways:  First is through the inter-aural time delay that occurs when sound reaches our two ears at different times — basically stereoscopic vision for sound. The second is through perception of the small phase shifts that also results from the separation of our ears.

Short-term delays tell us the size of the space in which we hear sound; long delays let us know the type of space we’re in (a marble cathedral or outdoors on a lawn, etc.).

In order for two speakers in a living room to reproduce a symphony orchestra recorded in a reverberant hall requires our ear-brain system to reconstruct an acoustic picture of the individual musicians, the orchestra as a whole, the sides and ceiling of the music hall, the audience and much more.

All stereo recordings contain some space and imaging information — either naturally captured with a few microphones or artificially induced with studio processing.  It’s this information that allows us to hear the three-dimensionality of a recording. Speakers deliver this information from the recording, but they also create additional reflections within the room as sound bounces off walls, floor and ceiling. This can be good or bad.

The important thing to note is that, in order to make the most of this cacophony of delayed sound arrivals, our ears need a way for each ear to hear all by itself.

Enter, the line source.  It minimizes the sound that is bounced around the room, and in doing so, allows the sound that does arrive at our ears to be as pristine and uncluttered as possible.  We can hear the best of the inter-aural delays that characterize space and imaging.

To achieve this, the Amazing Line Source is VERY tall to give it a special and complex wave-launch with a very elaborate driver interaction that delivers the image high than ear level. This interaction allows our ear-brain system to hear all the time delays in the program itself: 

  • those generated by the recorded program,

  • those generated by the room, 

  • the inter-aural time

  • delays produced by the geometry of the speakers,

  • inter-aural time delays caused by the special crossover components and the extreme overlap of the ribbon/woofer crossover bandwidth.

These overlaps, together with the six-inch time delay for sound travel between the woofer (and a similar but slightly smaller distance between the ribbons, combine to build a large acoustic space and an extensive, majestic sound stage.

When our ear-brain processing system hears this complex sound field, it lights up and says “Oooh!  That sounds like I am in the presence of a real live orchestra”.

Some of what you have just read totally flies in the face of orthodox teachings about how to design a speaker.  But it simply and inextricably follows how our ear-brain system works. Turning theory into reality has taken Bob twelve long years — he describes it as the most difficult design project of his career.

Listen to the Amazing Line Source and we are confident that you will be impressed with his final outcome.