A comparison of temporal measures of speech using spectrograms and digital oscillograms

To determine whether any systematic differences occur as a result of using spectrograms versus digital oscillograms to make durational measurements, a number of temporal features (e.g., voice onset time, vowel duration, and consonant closure duration) for 3 speakers were independently measured by 2 different investigators. Both experimenters measured the same intervals with conventional spectrograms and with digital oscillograms, separated by at least a 2-week interval. Oscillograms tended to reveal slightly longer vowel durations and more voicing during consonant closure, while spectrograms evidenced slightly longer consonant closure durations. In general, variations between the two types of instrumentation were no more than 8 to 10 ms and are, therefore, of primary consequence only for studies in which quite small temporal differences are critical.