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AES Journal Forum: Comment by Jont Allen on "Single-Channel Speech Enhancement Based on Subband Spectral Entropy"

Title: Single-Channel Speech Enhancement Based on Subband Spectral Entropy
JAES Volume 66 Issue 3 pp. 100-113; March 2018
Comment by: Jont Allen

I would recommend that the authors look at the following papers

Toscano, Joseph and Allen, Jont B (2014) Across and within consonant errors for isolated syllables in noise, Journal of Speech, Language, and Hearing Research, Vol 57, pp 2293-2307; doi:10.1044/2014_JSLHR-H-13-0244, (JSLHR,pdf, AuthorCopy)

Riya Singh and Jont Allen (2012); "The influence of stop consonants’ perceptual features on the Articulation Index model," J. Acoust. Soc. Am., apr v131,3051-3068 (pdf)

Feipeng Li and Jont B. Allen. (2011) Manipulation of Consonants in Natural Speech; IEEE Trans. Audio, Speech and Language processing, (officially published: Jul, 2010; Appearance date: Mar 2011) pp. 496-504. (pdf, Video-Demos, Video-Files)

These cite other papers that form the basis of these pubblications.

The work of Singh and Toscano, working with Allen, provide major insights into why the articulation index works.

The features that are used to identify the different consonants are distributed over about a 30 dB range. As the noise is increased (SNR decreased) these features are selectively masked. The net result is that the log of the average error is linear on a dB SNR scale. Understanding why the AI works the way it does, is imporant because it helps us understand the limitations of the analysis and method. For example, it explains Kryter's result of removing single bands, which seems to violate the AI method.

I hope you find these references useful in your research.

Jont Allen

Posted on April 13, 2018 at 5:36:25 PM EDT

AES Journal Forum: Comment by Scott Dorsey on "A New Professional Magnetic Recording Tape"

Title: A New Professional Magnetic Recording Tape
JAES Volume 1 Issue 1 pp. 10-16; January 1953
Comment by: Scott Dorsey

At the time this was published, pretty much all of the information in it was known to engineers at tape manufacturers, but this was likely the first time much of this was actually released to the general public.  At the time, audio tape coatings were just slurries of gamma ferric oxide in a binder with no other magnetic material added.  Engineers were very worried about particle size, shape, and distribution but the actual science behind optimizing these didn't exist.  So this was likely the first open publication describing the effects empirically and it set the stage for later research in more systematic modelling.

Posted on April 12, 2018 at 9:41:08 PM EDT

AES Journal Forum: Comment by Scott Dorsey on "On Aural Phase Detection: Part 2"

Title: On Aural Phase Detection: Part 2
JAES Volume 22 Issue 10 pp. 783-788; December 1974
Comment by: Scott Dorsey

This paper, and the paper before it, summarize work done a year earlier by Hansen and Madsen in a concise and clear fashion.  This provides no real data that wasn't in _Threshold of Phase Detection by Hearing_ but the presentation is more compact and clear as would befit a JAES paper.  Interestingly they find group delay is more readily audible in reverberant environments, quite the opposite of what Lipschitz, Pocock, and Vanderkooy found in _Preliminary Results on the Audibility of Midrange Phase Distortion in Audio Systems_ six years later.

Posted on April 3, 2018 at 5:29:15 PM EDT

AES Journal Forum: Comment by Scott Dorsey on "Motion Picture Sound Recording at USAF Lookout Mountain Laboratory"

Title: Motion Picture Sound Recording at USAF Lookout Mountain Laboratory
JAES Volume 2 Issue 4 pp. 204-214; October 1954
Comment by: Scott Dorsey

Back in the fifties when there wasn't a lot of common knowledge about newly developed facilties and production techniques, a big part of the AES was for engineers to talk to one another and discuss what they were doing.  So you will find a lot of papers from this era that just describe facilities and those papers are very cool because they provide insight into facilities and production techniques of that era.

This is a review of the sound mixing and transfer facility at what was perhaps the world's largest industrial film production operation at the time, making publicity and training films for the US Military.  A lot of effort was put into industrial-grade 16mm production as well as theatrical-grade 35mm films for release, and so the facility has a lot in common with both small local TV production facilities as well as with big Hollywood dubbing stages.  Work had begun at this time into making stereo mixes for Cinemascope release and fitting the facility up for that.

Howard Tremaine was much more famous for his work as an author of such works as the Audio Cyclopedia than for his work doing film production for the Air Force, so this paper is a look at a different side of a well-known pioneer.

Posted on February 11, 2018 at 7:14:45 PM EST

AES Journal Forum: Comment by Scott Dorsey on "Design of a Studio-Quality Condenser Microphone Using Electret Technology"

Title: Design of a Studio-Quality Condenser Microphone Using Electret Technology
JAES Volume 26 Issue 12 pp. 947-957; December 1978
Comment by: Scott Dorsey

Two previous versions of this paper had been given at conventions, but this one, published in the JAES, is the final and most complete one.  This is the paper that introduces the SM-81 and which contains a schematic of the early SM-81 (although people using this information for maintenance should beware that over the many decades in which the SM-81 has been manufactured the electronics have been completely revamped several times).

This paper is interesting for the insight into the design process of the SM-81 and into the various constraints on microphone performance which have not changed even today.  It is a useful source of service information for people who might be repairing the SM-81.  It is a useful source of design information for people who might be designing a new microphone.  When it came out, it was revolutionary; aside from a few Sony products of limited reliability, this was the first high performance electret microphone available to studios and sound reinforcement people, and it was the first condenser microphone of any sort that would work outside in the rain.  This paper explains why.

Posted on January 30, 2018 at 9:45:40 PM EST

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