International organisation for standardisation organisation internationale de normalisation

4.2.33D Audio

The Chair presented

m24712

Audio Issues for 100th MPEG meeting

S. Quackenbush

This summarized the Chair’s views of the most important open issues in the 3D Audio work. The presentation gave specifics of several possible evaluation tests. The Chair noted that live sports events are an important use case.

Juergen Herre, International Audio Labs / FhG-IIS, presented

m24859

Fraunhofer IIS 3D Audio Loudspeaker Setup and Room-Acoustic Properties

Andreas Silzle, Juergen Herre

The contribution noted that there are several 22.2-channel capable listening rooms in companies participating in MPEG Audio work. However, it is important that these rooms

• 
  Document their form factor
  
• 
  Document their noise level and reverberation characteristics. These should be largely in compliance with the specification in BS.1116.
  
• 
  Are able to have loudspeakers in agreed-upon loudspeaker positions e.g. 22.2, 11.1, 5.1 and stereo loudspeaker positions.
  
• 
  Have loudspeakers equalized and aligned in level and delay. For example, the “best” presentation of the reference program will most likely require delay equalization between the loudspeakers.
  

The contribution reports these characteristics for two listening rooms at FhG-IIS. One comes very close to fulfilling all requirements of BS.1116. Thomas Sporer, FhG-IDMT, noted that it is almost impossible for elevated speakers to fulfil the requirements of BS.1116.

The contribution also proposes a system for labelling the various loudspeakers and also documents a number of loudspeaker configurations that have significant presence in the marketplace.

Finally, the contribution noted that loudspeaker systems might use bass management, such that subwoofer receives both the LFE signal and the low frequency components of all other speakers.

Open issues:

• 
  Companies with listening rooms should document their test facilities if they are intended to be used by MPEG
  
• 
  Which loudspeaker setups should be tested? It would be best if the selected setups are “embedded.”
  

Kaneko-san, Univ. of Tokyo Polytechnic University, noted that the directivity of the loudspeakers also should be documented. This may be very much related to e.g. the number and configuration of drivers.

Akio Ando, NHK, noted that the audio material made available to MPEG was mixed in a room with loudspeakers arranged on the surface of a cylinder (not a sphere, and not a square). There was considerable discussion as to how to equalize this for presentation on the target loudspeaker configuration. Thomas Sporer, FhG-IDMT, suggested that channel-based content provide “mixed-room” loudspeaker positions to the encoder such that gain and delay equalization can occur.

Michael Kelley, DTS, noted that object-based representations might not require any gain or delay equalization.

Akio Ando, NHK, presented

m24631

Loudspeaker array integrated in frame of flat panel display for reproduction of 22.2 multichannel sound

Takehiro Sugimoto and Akio Ando

The contribution noted that NHK will begin UltraHiVision broadcasting in 2020. The contribution presents information on a prototype that integrates loudspeakers into the frame of a flat panel video display. This is termed Loudspeaker Array in Frame (LAF). The presenter noted that, with respect to the 22.2 channel loudspeaker setup, the front mid speakers, which would be “behind” the video panel, are difficult to emulate.

NHK has two designs:

• 
  116 loudspeakers in 85-inch video display
  
• 
  90 loudspeakers in 62-inch video display
  

The presenter showed videos of simulated wave propagation. Wave fronts were largely intact, but there was some distortion and null areas. In addition, both simulations and measurements confirm that the vertical and horizontal speaker arrays interfere to produce notches in the spectral envelope of the system response. The presenter also showed graphical simulation results suggesting that such a LAF would also work for smaller displays.

Juergen Herre, International Audio Labs / FhG-IIS, presented

m24860

New 3D Audio Test Items

Andreas Silzle, Hanne Stenzel, Juergen Herre,

The contribution reports on five new test items appropriate for 3D Audio, which are shown in the following table.