The Harvard sentences, sometimes called Harvard lines, are a collection of sample phrases that are used for standardized testing of Voice over IP, cellular, and other telephone systems. They are phonetically balanced sentences that use specific phonemes at the same frequency they appear in English.
IEEE Recommended Practices for Speech Quality Measurements sets out seventy-two lists of ten phrases each, described as the "1965 Revised List of Phonetically Balanced Sentences (Harvard Sentences)." They are widely used in research on telecommunications, speech, and acoustics, where standardized and repeatable sequences of speech are needed. The Open Speech Repository provides some freely usable, prerecorded WAV files of Harvard Sentences in American and British English, in male and female voices.
List 11 consists of the following ten phrases:
- Oak is strong and also gives shade.
- Cats and dogs each hate the other.
- The pipe began to rust while new.
- Open the crate but don't break the glass.
- Add the sum to the product of these three.
- Thieves who rob friends deserve jail.
- The ripe taste of cheese improves with age.
- Act on these orders with great speed.
- The hog crawled under the high fence.
- Move the vat over the hot fire.
- "Why it’s so hard to make CGI skin look real" (at 7m13s), Vox, 3 August 2021.
- "IEEE Recommended Practice for Speech Quality Measurements". IEEE Transactions on Audio and Electroacoustics. 17 (3): 225–246. September 1969. doi:10.1109/TAU.1969.1162058. Retrieved 2012-01-05.
- "The Open Speech Repository". Retrieved 2012-01-05.
- "Harvard Sentences". Retrieved 2012-01-05.
- Zhang, Sarah (2015-03-09). "The 'Harvard Sentences' Secretly Shaped The Development Of Audio Tech". Gizmodo.
- "harvardsentences.com". 2021-03-01.