Speech timing lag

A speech timing lag is the time difference between corresponding events in two speech recordings. Define ${\Delta }_i=t_{B,i}-t_{A,i}$ for landmark $i$. Positive values mean speaker B's event occurs later; negative values mean B leads. The landmark might be a specified syllable onset or phrase boundary, so its definition is part of the measurement.

In synchronous speech experiments, Fred Cummins recorded paired readings and compared corresponding events. Typical differences were about $40\mathrm{ms}$ on average, with larger mismatches at phrase beginnings.^[ref]

Different summaries answer different questions. For illustrative lags $10,20,-30\mathrm{ms}$, the arithmetic mean is zero, the mean absolute value is $20\mathrm{ms}$, and the root mean square isZero average leadership therefore does not imply close alignment at every event. The square gives larger mismatches more influence on the final statistic.

Recording delays also matter. If channel B adds a known $12\mathrm{ms}$ delay relative to channel A, then ${\Delta }_{\mathrm{recorded}}={\Delta }_{\mathrm{speech}}+12\mathrm{ms}$ under this sign convention. Subtracting that calibrated offset separates equipment delay from speaker timing. Consistent landmark annotation and synchronized recording are consequently necessary for interpreting the measured lag.