Reflecting sound from acoustically reflective video screen
View Patent ↗In an audiovisual system, in which video is displayed on a screen that does not permit sound to pass through the screen, such as a light emitting diode panel, a high-frequency speaker positioned above an audience seating area can direct sound toward the screen, so that the screen can reflect the sound toward the audience seating area. The high-frequency speaker can be used with one or more low-frequency speakers positioned at or near the height of the audience seating area. The low-frequency and high-frequency sounds can appear to originate from close to the same height, thereby creating a realistic audio image at the audience seating area. A spectral filter can negate the spectral effects of propagation to and reflection from the screen. Suitable time delays can synchronize the high-frequency sound with the low-frequency sound and with video displayed on the screen.
1. An audiovisual system, comprising:
a screen viewable from an audience seating area and configured to display video corresponding to a video signal; and
an elevatable high-frequency speaker positionable at a first height relative to the audience seating area,
the high-frequency speaker configured to produce a high-frequency sound in response to a high-frequency signal,
the high-frequency signal generated in response to a full-frequency audio signal that is associated with the video signal,
the high-frequency signal including frequencies in the full-frequency audio signal that are above a crossover frequency,
the high-frequency speaker configured to direct the high-frequency sound at the screen,
the screen further configured to reflect the high-frequency sound toward the audience seating area.
2. The audiovisual system of claim 1 , wherein the crossover frequency is between 200 Hz and 400 Hz, such that human vocals in the full-frequency audio signal are directed into the high-frequency speaker.
3. The audiovisual system of claim 1 , further comprising a controller configured to receive the full-frequency audio signal associated with the video signal, and, in response to the full-frequency audio signal, generate the high-frequency signal.
4. The audiovisual system of claim 3 ,
wherein the controller is further configured to generate a low-frequency signal in response to the full-frequency audio signal, the low-frequency signal having frequencies below the crossover frequency; and
further comprising a low-frequency speaker positioned at or near a height of the audience seating area, the low-frequency speaker configured to produce low-frequency sound in response to the low-frequency signal, the low-frequency speaker configured to direct the low-frequency sound directly at the audience seating area.
5. The audiovisual system of claim 4 , wherein the controller is further configured to apply a spectral filter to the high-frequency signal, the spectral filter selected to adjust the spectral content of the reflected high-frequency sound to mimic a condition in which the high-frequency speaker is positioned at the height of the low-frequency speaker and configured to direct the high-frequency sound directly at the audience seating area.
6. The audiovisual system of claim 5 , wherein the controller is configured to determine the spectral filter based on a first measured signal, taken from sound reflected from the screen, and a second measured signal, taken from sound emitted directly from the high-frequency speaker.
7. The audiovisual system of claim 6 , wherein the controller is configured to select the spectral filter from a plurality of predetermined spectral filters that correspond to a respective plurality of distances between the high-frequency speaker and the screen.
8. The audiovisual system of claim 4 , wherein the controller is further configured to impart a first time delay between the low-frequency signal and the high-frequency signal, the first time delay selected to synchronize the high-frequency sound with the low-frequency sound.
9. The audiovisual system of claim 8 , wherein the controller is further configured to impart a second time delay to both the low-frequency signal and the high-frequency signal, the second time delay selected to synchronize the high-frequency sound and the low-frequency sound with the displayed video on the screen.
10. The audiovisual system of claim 9 , wherein the controller is further configured to impart a third time delay to both the low-frequency signal and the high-frequency signal, the third time delay selected to account for time-of-flight propagation of sound from the screen to the seats in the audience seating area such that the high-frequency sound and the low-frequency sound appear to emerge from the screen.
11. The audiovisual system of claim 1 , wherein the screen is flat and has a surface that specularly reflects the high-frequency sound.
12. The audiovisual system of claim 1 , wherein the high-frequency speaker has an emission pattern that is operably wider along a vertical direction than along a horizontal direction.
13. The audiovisual system of claim 12 , wherein the high-frequency speaker includes multiple sound-producing elements that shape the emission pattern of the high-frequency speaker.
14. A method, comprising:
displaying, on a screen viewable from an audience seating area, video corresponding to a video signal;
receiving, with a controller, an audio signal associated with the video signal;
generating, with the controller, in response to the audio signal, a low-frequency signal having frequencies below a crossover frequency and a high-frequency signal having frequencies above the crossover frequency;
producing, with a low-frequency speaker, lo frequency sound in response to the low-frequency signal;
directing, with the low-frequency speaker, the low-frequency sound directly at the audience seating area;
producing, with a high-frequency speaker positioned above the audience seating area, high-frequency sound in response to the high-frequency signal;
directing, with the high-frequency speaker, the high-frequency sound at the screen; and
reflecting, with the screen, the high-frequency sound toward the audience seating area.
15. The method of claim 14 , further comprising imparting, with the controller:
a first time delay between the low-frequency signal and the high-frequency signal, the first time delay selected to synchronize the high-frequency sound with the low-frequency sound;
a second time delay to both the low-frequency signal and the high-frequency signal, the second time delay selected to synchronize the high-frequency sound and the low-frequency sound with the displayed video on the screen; and
a third time delay to both the low-frequency signal and the high-frequency signal, the third time delay selected to account for time-of-flight propagation of sound from the screen to the seats in the audience seating area such that the high-frequency sound and the low-frequency sound appear to emerge from the screen.
16. The method of claim 14 , further comprising applying, with the controller, a spectral filter to the high-frequency signal, the spectral filter selected to adjust the spectral content of the reflected high-frequency sound to mimic a condition in which the high-frequency speaker is positioned at a height of the low-frequency speaker and configured to direct the high-frequency sound directly at the audience seating area.
17. An audiovisual system, comprising:
a screen viewable from an audience seating area and configured to display video corresponding to a video signal;
a controller configured to receive an audio signal associated with the video signal, and, in response to the audio signal, generate a low-frequency signal having frequencies below a crossover frequency and a high-frequency signal having frequencies above the crossover frequency;
a low-frequency speaker configured to produce low-frequency sound in response to the low-frequency signal, the low-frequency speaker configured to direct the low-frequency sound directly at the audience seating area; and
a high-frequency speaker positioned above the audience seating area, the high-frequency speaker configured to produce high-frequency sound in response to the high-frequency signal, the high-frequency speaker configured to direct the high-frequency sound at the screen, the screen further configured to reflect the high-frequency sound toward the audience seating area.
18. The audiovisual system of claim 17 , wherein the controller is further configured to impart:
a first time delay between the low-frequency signal and the high-frequency signal, the first time delay selected to synchronize the high-frequency sound with the low-frequency sound;
a second time delay to both the low-frequency signal and the high-frequency signal, the second time delay selected to synchronize the high-frequency sound and the low-frequency sound with the displayed video on the screen; and
a third time delay to both the low-frequency signal and the high-frequency signal, the third time delay selected to account for time-of-flight propagation of sound from the screen to the seats in the audience seating area such that the high-frequency sound and the low-frequency sound appear to emerge from the screen.
19. The audiovisual system of claim 17 , wherein the controller is further configured to apply a spectral filter to the high-frequency signal, the spectral filter selected to adjust the spectral content of the reflected high-frequency sound to mimic a condition in which the high-frequency speaker is positioned at a height of the low-frequency speaker and configured to direct the high-frequency sound directly at the audience seating area.