In Anonymus' reading, the stress on is is cued by a higher than expected pitch and a complex intonation contour. On spent too there is the same complex intonation contour, while also suggesting a falling terminal contour with a barely-audible rising end (on /n/). This is supplemented by an enormous difference in duration. The duration of spent is 644 msec; that of is is 252 msec. As a result of the trade-off between pitch and duration, the stress on spent breaks even with (even surpasses) the stress on is. Notice the 81-msec pause preceding the /p/, and the huge 150-msec pause following the /n/, before the minute stop release. Such pauses in mid-word are not perceived as periods of silence, but as closure of the vocal track in overarticulating the consonants /p/ and /n/.
Figure 1 Wave plot and pitch contour of "how my light is spent" read by Anonymus. The lower window presents the wave plot display which shows a plot of the wave amplitude (in volts) on the vertical axis, as a function of time (in milliseconds) on the horizontal axis. The upper window presents a fundamental frequency plot, which displays time on the horizontal axis and the estimated glottal frequency (F0 = pitch) in Hz on the vertical axis.
In the first line of this sonnet caesura occurs after position 5, after consider. Indeed, in Barrett's reading there is a feeling that the line is clearly articulated at that point. The nature of this will be better understood when listening to the first line in Anonymus' reading too, where how is perceived as unduly close to consider, and the integrity of the line is jeopardized. There is, however, no measurable pause in either of these readings after consider. A few measurements, however, may solve the mystery. The duration of the whole first line in Anonymus' reading is 3.060 msec; in Barret's reading only 2.602 msec; that is, the former is almost 1.2 times longer than the latter, or 458 msec longer. Measurements regarding the word consider, by contrast, indicate inverted proportions. The duration of consider is 738 msec long in Barrett's reading, whereas in Anonymus' reading it is only 503 msec. In other words, the former is 1.7 times longer than the latter, or 235 msec longer. These proportions become even more extreme in the last syllable,
The duration of this syllable is 298 msec in Barrett's reading, 145 msec in Anonymus's reading; that is, the former is over twice as long as the latter. This is a typical example of the principle that discontinuity can be indicated by prolonging the duration of a word, a syllable, or a phoneme, as in fermata in music. Listen again to the two readings of the first line.
Listen to the verse lines "though my soul more bent / To serve therewith my Maker, and present / My true account" excized from Sean Barrett's and Anonymus' readings.