delay, computers. l This paper is wo
(1) l My company is Valve Research. I also work in solid state design and use digital tool; delay, computers. l This paper is work relating to have headphones sound more like loudspeakers. l Other researchers may be trying to achieve this using software. I wanted to understand the concept using hardware that could be used by others. (2) l Stereo is listening with both ears to hear all incoming sound. l Binaural is left ear hearing left channel only etc. (3) l Blumlein binaural patent in 1931 l Note baffles at b and between loudspeakers. l Microphones a1 and a2 l Shuffle circuit C l Blumlein known as inventor of stereo. (4) l Both ears hear both speakers l Different amplitude of sound from each speaker to both ears. l Different delay of sound from each speaker to both ears l Frequency response changes to each ear due to head shape. i.e. nose etc. l Position B and D (i.e. 1/2 left, 1/2 right) is also different for speakers & headphones. (5) l Processor has crossfeed i.e. Bauer, Ref 2 or Linkwitz, Ref 3 to approach stereo in headphones and headphone amp. l Also my processor using time delays to remove the between ears dominance i.e. due to mid solo etc. (6) (7) (8) (9) l My triple delay system having matched left and right channels and a centre channel of 2 to 3 times different. l There are 6 paths total. l Photo shows 3 digital delay units Left and right of 5mS and centre of 15mS. l Also mic preamp on LHS and switch boxes and crossfeed box on RHS. l Reference mics near dummy head (green) l In ear mics in dummy head (red) l After calibrating dummy head mics. l Processor now has crossfeed, 3 delay units, switching and headphone amp. (10) l Dummy head with small electret mics. (11) l Dummy head with open headphones. (12) l Dummy head with closed headphones. (13) l Calibrating mics shown. (14) l Dummy head listening to loud speakers. l Human using closed headphones (so as to not hear loudspeakers) listening to dummy head’s mics only. l Human can also remove headphones quickly to hear speakers for comparison. l See slide number 9. (15) l My microphone amplifiers as required. 4 used. (16) l Questions?
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