SPHEROVOX PENTAHORN OMNIVOX / DODECAHEDRON CORNER FOLDED HORN ACOUSTIC MEASUREMENTS LATEST DEVELOPMENT ABOUT US CONTACS
OMNIVOX VERSUS SPHEROVOX COMPARISONS SUMMARY AND CONCLUSIONS
AUDIO ENGINEERING SOCIETY (AES)
PRESENTATION   [PowerPoint] [Acrobat]

OMNIVOX VERSUS SPHEROVOX COMPARISONS
NEWS The Audio Engineering Society Comes to Los Angeles for 137th International AES Convention
AES137 to feature busy itinerary of numerous track sessions, including Recording and Production, the Project Studio Expo, Networked Audio, and more More...
AES136 Berlin Highlights Project Studio Expo and Special Sound for Picture Programming
Celebrating the success of the 136th Audio Engineering Society Convention, which took place April 26 - 29, 2014 at the Estrel Hotel and Convention Center in Berlin, Germany, the AES continues to forge new territory with its successful tracks and programs at recent Conventions. More...
AES Showcases Latest Audio Innovations and Best Practices at 136th International Convention in Berlin
Successful Technical Program and Exhibition draw high attendance and positive response from attendees and exhibitors alike More...
Search
Search
OMNIVOX VERSUS SPHEROVOX COMPARISONS For direct comparison, same dodecahedron and spherical sound source graphics for 2 kHz and 4 kHz are arranged in the same sequence. The measurements have been performed under the same measurement conditions, equipment and equipment settings.

From spherical sound source polar patterns, an about 5dB maximum deviation within 10° angular segment is readable, meaning that about 2o angular resolution will bring about the same impulse response measurement precision for automatic polar pattern construction, provided the same 1dB maximum error be tolerated. Because of rotational and planar symmetry, only a quarter of a circle is needed, or just 45 number of IR measurements of the spherical sound source are enough to have the same precision as with dodecahedron with 64k plus measurements.

Worst Case Directional SPL Differences  Spherovox vs Omnivox -1/3 and 1/1 octave bands Worst Case Directional SPL Differences Spherovox vs Omnivox -1/3 and 1/1 octave bands
Worst Case Directional SPL Differences Spherovox vs Omnivox -1/3 and 1/1 octave bands
To summarize all comparatively measured results, a common electronic table chart was generated, showing the worst directional SPL differences in free field at any octave, and any 1/3 octave within 2kHz and 4kHz octave bands. Maximum dodecahedron directional SPL variations for 2kHz and 4kHz octaves are correspondingly 8dB and 11dB.

Maximum 1/3 oct variations are 10db, 13dB and 14 dB for 1.6kHz, 2kHz and 2.5kHz correspondingly.

Next three 1/3 octaves (3.15kHz, 4kHz and 5kHz) have correspondingly 16dB, 19dB and 18 dB maximum SPL directional variations. Spherovox’s SPL directivity deviations are more than twice lower at any frequency for 1/3 and 1/1 octave band.

Much clearer comparison between Spherovox and Omnivox is visible on the presented off-axis frequency response characteristic families at the same angular increments of 15°. All characteristics are measured at the same distance of 2m from the source center, with exactly the same settings. Obviously, Spherovox exhibits smaller individual frequency response irregularities and narrower range of the total SPL deviations.

“Omnivox”- direct SPL off-axis frequency responses at 15o increment. “Omnivox”- direct SPL off-axis frequency responses at 15o increment.
“Omnivox”- direct SPL off-axis frequency responses at 15o increment.
“Spherovox” direct SPL off-axis frequency responses at 15o increment. “Spherovox” direct SPL off-axis frequency responses at 15o increment.
“Spherovox” direct SPL off-axis frequency responses at 15o increment.
SUMMARY AND CONCLUSIONS It is impractical to have the real high resolution dodecahedron 3-D polar pattern measured. It is very difficult and hardly practical to accurately measure or calculate directivity factor (or directivity index) of dodecahedron sound source, either. Maximum directional SPL deviation in any octave or 1/3 octave frequency band however could easily be evaluated by a single polar pattern in any arbitrary measurement plane, determined by at least two loudspeaker axes. During acoustic measurements by dodecahedron omni type sound source, directions of lobes and notches in radiation patterns are not intuitively recognized and could not trigger warnings if some spatial acoustic parameters seem to have unrealistic measured values. It should be pointed out that for IACC measurements with dodecahedrons, doubled maximum variation values between left and right received reflected signals might be expected, i.e. 30 dB L/R 1/3 octave band SPL variation values, and about 20 dB octave ones for 2kHz to 4kHz bands.

Spherovox, unlike the dodecahedron, allows to be fully described by a single polar pattern for any frequency, thus providing the full 3-D balloon. Should measurement data be needed for automatic 3D balloon diagram construction, only 36 discrete impulse response measurements have to be carried out in a quarter of a circle at 2.5° vertical resolution.

As it could be seen from the presented Spherovox patterns, symmetric left to right first order wall reflections might be expected to be within a maximum of 2-3 dB SPL variation range, due to the source’s own interferences. This is 10 times better, compared with measurements made by Omnivox dodecahedron.
Print Top Send