{"id":8460,"date":"2025-04-14T10:00:29","date_gmt":"2025-04-14T08:00:29","guid":{"rendered":"https:\/\/www.tonmeister.ca\/wordpress\/?p=8460"},"modified":"2025-04-14T10:02:44","modified_gmt":"2025-04-14T08:02:44","slug":"phantom-imaging","status":"publish","type":"post","link":"https:\/\/www.tonmeister.ca\/wordpress\/2025\/04\/14\/phantom-imaging\/","title":{"rendered":"Phantom imaging"},"content":{"rendered":"\n

The July 1968 issue of Wireless World Magazine<\/a> contains a description of an early, but interesting analysis of the relationship between phantom image placement in a 2-channel stereo system and interchannel level differences. This is an old favourite topic of mine, originally inspired by the work of Michael Williams and his “Stereophonic Zoom”, and extending to my first AES paper in 1999.<\/p>\n\n\n\n

If you, like me, are interested in this (for example, if you’re making a panning algorithm or you’re testing the veracity of headphone-based “virtual” systems), some important figures from that article are shown below.<\/p>\n\n\n

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The typical way of showing the relationship between IAD and phantom image placement.<\/figcaption><\/figure>\n<\/div>\n\n
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This one is interesting because it shows the different results in different rooms, (which would also be influenced by loudspeaker directivity.)<\/figcaption><\/figure>\n<\/div>\n\n\n

Note that, for the plots above and below, the x-axes show the position of the image in the stereo sound stage, where 0 is the centre point between the two loudspeakers and 0.5 is a position in one of the two loudspeakers. This is 0.5 because it’s one-half of the total angular distance between the two loudspeakers. So, you can consider the loudspeaker aperture as \u00b10.5.<\/p>\n\n\n

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The relationship between image WIDTH and position. This is something I’ve not seen expressed so clearly before.<\/figcaption><\/figure>\n<\/div>\n\n\n

For more information similar to this, see these links as a start:<\/p>\n\n\n\n