Envelope following responses to natural vowels.

Envelope following responses to natural vowels were recorded in 10 normal hearing people. Responses were recorded to individual vowels (/a/, /i/, /u/) with a relatively steady pitch, to /[symbol: see text]/ with a variable and steady pitch, and to a multivowel stimulus (/[symbol: see text]ui/) with a steady pitch. Responses were analyzed using a Fourier analyzer, so that recorded responses could follow the changes in the pitch. Significant responses were detected for all subjects to /a/, /i/ and /u/ with the time required to detect a significant response ranging from 6 to 66 s (average time: 19 s). Responses to /[symbol: see text]/ and /[symbol: see text]ui/ were detected in all subjects, but took longer to demonstrate (average time: 73 s). These results support the use of a Fourier analyzer to measure envelope following responses to natural speech.