1. Rumsey Chapter 16 Day 3

2. Overview  Stereo = 2.0 (two discreet channels)  THREE-DIMENSIONAL, even though only two channels  Stereo listening is affected by: THE ROOM, LISTENING POSTION, SPEAKER POSITION  Most PRACTICAL way to listen

3. Principles of Loudspeaker Stereo  PHANTOM IMAGES: We hear sound from BETWEEN the speakers even though a speaker is not there  Multi-channel sound was first researched by BELL LABS  Remember: LOUDNESS, DELAY, and FREQUENCY help us to determine the location of sound

4. More on Phantom Images  Figure 16.2  Place speakers 30 degrees from center on each side  Create a perfect TRIANGLE with the listener  Best phantom imaging, or “Summing Localization”

5. Binaural vs. Stereophonic  BINAURAL refers to localization of an individual source  STEREOPHONIC is the way we use a stereo source to create a simulation  Fact file 16.1

6. More on Binaural  Tries to be NATURAL sounding by re-creating the EARS on your head!  Must accurately re-created the HRTF  Problems happen because we must keep our head STILL when listening  There can also be problems with exact reproduction  “Binaural Haircut”

7. Two-Channel Mic Techniques  Spaced Pair  X/Y Pair “COINCIDENT Pair”  Blumlein  Midside (MS)  Near-Coincident Pairs  Decca Tree

8. Issues with Stereo Micing  Fact File 16.5  Frequency Response and Level can skew the stereo image  PHASE will change the natural sound reproduction and perception of space  CROSSTALK: 18dB level difference makes the signal seem fully left or right

9. Stereo Width  Fact File 16.6  NULL POINT: Changes “Fully left or right”  Widening the mics makes the stereo image more extreme  Wide mics = narrow angle between fully left and right = wide sound stage

10. Mic Configurations  Fact File 16.7  END-FIRE and SIDE-FIRE configurations  End-Fire allows for the mic to be directly pointed at the source  Side-Fire usually stands vertically

11. Spaced Microphones  Rely on the PRECEDENCE effect: The delay between the capsules  Also changes based on volume and frequencies  Can capture a very wide sound stage  LESS ACCURATE natural imaging: Must be careful to maintain accuracy if that is what you want

12. Dummy Heads  Actual model of the human head  Use of Pressure Microphones  Simulates how the human ear captures sound

13. Stereo Studio Setup  Multi-Mic: Levels are panned to a “virtual” stereo position  Some sources still warrant natural stereo reproduction: Acoustic guitar, piano, drums  “PANNED MONO” creates an artificial stereo image  Close micing is used often, but must be done with care so as not to disrupt the stereo image