In March of 2017 I conducted at subjective test to assess the quality of the NJ Transit TETRA speech communications system. The test was conducted at the Nokia Bell Labs facility with more than 40 subjects, who were NJ Transit employees. Many were bus operators and so were familiar with the quality of the current communications system.
Late in 2016 I designed and supervised a subjective audio quality test of the Low Complexity Profile of MPEG-H 3D Audio. The tests covered a range of bit rates, from 768 kb/s to 48 kb/s and a range of “immersive audio” use cases, from 22.2 to 2.0 channel presentations. Seven test sites participated in the tests with a total of 288 listeners. This resulted in a data set of 15576 individual scores. The report, N16584 MPEG-H 3D Audio Verification Test Report, was published at the 117th MPEG meeting and is available at http://mpeg.chiariglione.org/standards/mpeg-h/3d-audio.
In the first part of 2011 I designed and supervised a subjective audio quality test of the Baseline Profile of MPEG-D Unified Speech and Audio Coding. The tests included speech, music and speech mixed with music, and covered a large range of bit rates from 8 to 96 kbps as well as both mono and stereo operating points. Depending on the listening test, 6 to 13 test sites participated with a commitment to use at least 8 listeners per test. This resulted in a large data set of more than 38000 individual scores. The report, N12232 Unified Speech and Audio Coding Verification Test Report, is available at http://mpeg.chiariglione.org/standards/mpeg-d/unified-speech-and-audio-coding.
In mid 2010 I designed and supervised a subjective audio quality test of the MPEG-D Spatial Audio Object Coding technology. This technology permits multiple audio “objects” which are each in a separate audio input channel to be mixed together into one or two channels, compressed using MPEG AAC, and then decoded to recover the separate audio object channels.
The report, N11657 Report on Spatial Audio Object Coding Verification Tests, is available at http://mpeg.chiariglione.org/standards/mpeg-d/spatial-audio-object-coding.
In 2008 I designed and supervised a subjective audio quality test of the MPEG-4 Advanced Audio Coding, Low Delay (AAC-LD) technology. This technology has performance similar to MPEG-4 AAC, but with one-way latency as low as 10 ms. The report, N10032 Report on MPEG-4 AAC-ELD Verification Tests, is available at http://mpeg.chiariglione.org/standards/mpeg-4/audio.
Late in 2006 I designed and supervised a subjective audio quality test of the MPEG-D MPEG Surround technology. The technology is able to represent a 5.1 channel audio signal as a stereo signal with a bitrate of 128 kb/s to as slow as 64 kb/s, such that it can be a “drop-in” replacement to give current stereo services a 5.1 channel capability. The report, N8851 Report on MPEG Surround Verification Tests, is available at http://mpeg.chiariglione.org/standards/mpeg-d/mpeg-surround.
In 2005 I designed and supervised a subjective audio quality test of the MPEG-4 Lossless Coding standards. Both of these standards permit bit-exact recovery of the input signal with approximately 2:1 compression. The MPEG-4 SLS standard permits decoding of a variable number of bits so as to permit the decoded signal to vary from bit-exact lossless (decoding the most bits) to perceptually lossless (decoding the fewest bits). The reports, N7686 Verification Report on MPEG-4 ALS, and N7687 Verification Report on MPEG-4 SLS, are available at http://mpeg.chiariglione.org/standards/mpeg-4/audio.
In 2005 I designed and supervised a subjective audio quality test of the MPEG-4 High Efficiency Advance Audio Coding Version 2 technology. This technology is perhaps the most widely deployed MPEG Audio technology in that it is present in more than 8 billion smart phones worldwide. It delivers entertainment quality audio at bitrates as low as 32 kb/s for a stereo signal. The report, N7137 Listening Test Report on HE-AAC V2, is available at http://mpeg.chiariglione.org/standards/mpeg-4/audio.