Earlier this month loudspeaker designer Siegfried Linkwitz presented an AES lecture in London on room-optimized stereo sound reproduction through proper loudspeaker design and placement, which I previewed in my blog post Linkwitz on loudspeakers and room interaction. An audio recording of the Linkwitz lecture (MP3, 24.5 MB) - which was presented last November 13th - is now available from AES, as is a lecture report.
In the lecture - "Accurate sound reproduction from two loudspeakers in a living room" - Linkwitz advocates the design and use of omnidirectional or dipole loudspeakers with a uniform polar response symmetrically placed in a room with respect to room boundaries and listener position. This, he says, helps to achieve a spectrum of reflection that is the same as that of the direct sound, minimizing confusing cues from the room that interfere with the illusion of listening into the different space of a recorded acoustic event.
Linkwitz also takes to task the typical design approach behind most of today's loudspeakers, which he says are mostly "boxes" that are omnidirectional at low frequencies and forward directional at high frequencies. Other current practices that he says are interfering with optimum sound reproduction include non-symmetrical placement of loudspeakers in rooms, room treatments that don't affect all frequencies equally (they're typically not broadband), and recording practices that have no hope of capturing a coherent acoustic space.
He's also skeptical that electronic room equalization will prove to be much of an answer, and not impressed so far with surround sound. At the same time, Linkwitz says, properly set up stereo "is impressive in its simplicity."
Much of his experience and research in this area comes from his own and others' experiments with loudspeakers that have been built and tested based on many of the above criteria. Details on his dipole and omnidirectional loudspeaker designs, including construction plans and building details, are available on the Linkwitz Lab website.
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