Speaking Speed
We measure how fast every file is actually being read - silences and all - then flag any chapter that pulls too far from the batch median.
Spot the outliers in one look
Here's a mock batch of eight files. The median sits at 148 WPM. Two files drift more than 15% from the median and get flagged for regeneration.
Words per minute by file
What makes this measurement honest
A raw "word count / duration" calculation is misleading because real text-to-speech output is full of pauses. Here's what we actually measure.
Word-level timing
We know exactly when each word in the file starts and ends - not just where sentences break. That's the foundation for a speaking rate you can actually trust.
Silence is not slow
A file that sits in dead air for thirty seconds isn't "slow" - it's paused. We exclude long silences so the WPM you see reflects the actual speaking, not the dead time in between.
Language-robust
Word length varies wildly across languages. Under the hood we measure speed in a language-neutral way and report a WPM number that stays meaningful whether you're generating English or German.
Batch consistency score
The whole batch gets a 0-100 consistency score. Tight batches stay near 100; the more files that drift, the harder the score drops.
What you get back per file
Words per minute
Silence-adjusted WPM for every file, measured from word-level timestamps.
Deviation from median
Signed percentage showing whether each file is faster or slower than the batch.
Outlier flag
True when a file's pace drifts beyond your configured threshold, default 15%.
Real reports from real batches
"For audios longer than 1.5-2mins, gpt-4o-mini-tts works really unstable: random pauses from few seconds to more than a minute, random volume and tone changes, repeating last few sentences in random order."
"The OpenAI voices are excellent in terms of realism but they sometimes skip phrases and on occasion, entire paragraphs. Sometimes when submitting a single word, the API will return silence."
"I'm having the exact same issue with having very long silences in the audio. It's quite weird."
"The only issue I have had is that I have to create pause blocks to stretch the time frame out instead of moving a block over in the timeline."
Keep your audio pacing consistent
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