Importance of Vowel Harmonic Phase and Fundamental Frequency for Envelope Following Responses

The results of experiment 1 support that, in addition to f0, other stimulus factors affect EFR amplitude. Experiment 2 supports that harmonic phase spectra are an important stimulus characteristic for EFR amplitude and that EFRs elicited by natural vowels can be simulated adequately by modeling f0 and harmonic amplitude and phase spectra. Results of experiment 3 support that alignment of stimulus beating envelopes, presumed to be generated in the cochlea between adjacent pairs of harmonics, can lead to larger scalp-recorded EFRs. Designing vowel stimuli with low f0 and harmonic phases optimized to encourage envelope alignment could improve EFR amplitudes and reduce the recording time required to detect them in some individuals.