When is it not a good idea to quote?
First, time-domain measures of pulse shapes made on inverse filtered signals are accurate only if phase information is completely preserved during recording. This requires either the use of a pneumotachographic mask or a microphone with a low-frequency response near zero. However, not all listeners can hear changes in harmonic phase, even through headphones; and for those who can, the perceptual effect is small compared with changes in spectral slope or harmonic amplitudes (Plomp & Steeneken, 1969). Given this relative insensitivity to phase information in complex tones, spectral measures may adequately characterize listeners' perceptions of voice quality while sparing experimenters the burden of applying special phase-preserving recording techniques.
“During the conference I was staying with my sister in Syracuse. I brought the paper home and said to her, “I can’t understand these things that Lee and Yang are saying. It’s all so complicated.”
“No,” she said, “what you mean is not that you can’t understand it, but that you didn’t invent it. You didn’t figure it out your own way, from hearing the clue. What you should do is imagine you’re a student again, and take this paper upstairs, read every line of it, and check the equations. Then you’ll understand it very easily.”
I took her advice, and checked through the whole thing, and found it to be very obvious and simple. I had been afraid to read it, thinking it was too difficult.”
Look for the first time the concept is mentioned. Typically that will be when details are given and/or a reference. Look up the reference. You can also look up more review/textbook explanations, but be aware that those may not be what the authors intended, which is why it is better to start out with what the authors say themselves and what references thye give.
Although the original set of source parameters was derived from principal components analysis, which yields orthogonal factors, the current set deviates sufficiently from those results that quasi-independence cannot be assumed. In addition, the extent of possible independence is constrained by the approximately −12 dB/octave decrease in source spectral energy reported by Flanagan (1957b). However, the extent to which naturally occurring spectral roll-off deviates from this ideal pattern, and the perceptual importance of any such deviations, is not currently known. For these reasons, three experiments were undertaken to assess acoustic and perceptual dependencies among model parameters. In
OK, let's check out Flanagan (1957b)
Example: Long-term average spectrum in Kreiman et al. 2007
First mention: page 599
A number of studies have sought to circumvent this difficulty by estimating the glottal source spectral slope directly from the complete oral speech signal. Two approaches have been taken. In the first approach, the long-term average spectrum (LTAS) of the voice is calculated over a long sample of connected speech—30 s or more—on the assumption that the influence of varying vocal tract resonances on spectral shape will average out across the sample, yielding a measure that approximates the overall source contribution.