Fact · Accessibility and health
8.27percent word error rate
In our October 2026 test on a Mac with an M2 Pro, Apple SpeechTranscriber had a word error rate of 8.27 percent on 26 Italian readings of ten short sentences by 22 people with Parkinson's disease aged 40 to 80.
Measured by us on October 23, 2026, from 26 recordings
Our own measurement
This number comes from our benchmark, not from another publication. The full record (the setup, every recording's checksum, every transcript and timing) is published, so you can recompute it.
- What it measures
- Apple's on-device speech model in macOS 26 (SpeechAnalyzer with a SpeechTranscriber module, transcription preset), with the locale given (en-US, de-DE, fr-FR, es-MX, it-IT, pt-BR). The speakers read a printed text aloud in a quiet room with a microphone 15 to 25 cm away (Italian Parkinson's Voice and Speech, University of Bari and ASL Bari, recorded 2016 and 2017). The reference is the text they were given, so a word a speaker skipped or changed counts as an error for every engine alike.
- How it is measured
- Word error rate = 114 word errors / 1,378 reference words = 8.27 percent, over 26 recordings (16.2 minutes of audio). The 95% interval over speakers is 5.37 to 11.57 percent.
- What it does not show
- Against healthy speakers aged 60 to 77 reading the same text, this is +2.97 points; the 95% interval for that difference, allowing for the test's 9 comparisons, is -1.58 to +8.25 points, which includes zero, so this test cannot tell the difference apart from chance. 22 speakers from one region of Italy, in one language, reading a fixed text: a person dictating their own words, in another language or with more advanced Parkinson's may fare differently. Half of these speakers had an error rate of 5.7 percent or less, the highest was 30.2 percent.
In the data
A row of Dictation Accuracy With Parkinson's Speech, Tested, as Apple SpeechTranscriber, People with Parkinson's disease, read phrases: 5.37 to 11.57 percent.
- Engine
- Apple SpeechTranscriber
- Maker
- Apple
- Speakers
- People with Parkinson's disease
- What they read
- Read phrases
- Speakers in group
- 22
- Recordings
- 26
- Language
- Italian