Manipulating envelope and fine structure separately reveals their competing roles in tone perception.

Evidence

In order to avoid the blurriness between E and FS in the chimeric stimuli, we adopted a lowpass filter (cut-off at 64 Hz) for extraction of the envelopes from the filters. By analysing the tone responses to the chimeric tone tokens, we could understand the competing roles of FS and E in tone perception in various groups of listeners. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3384

Three groups of adult subjects, including 15 NH subjects (8 females and 7 males), 16 patients with SNHL (10 females and 6 males), and 27 patients with ANSD (9 females and 18 males), participated in the present study. The subjects with SNHL had hearing loss ranging from moderate to severe degree, and the ANSD subjects had hearing loss ranging from mild to severe. The original tone materials consisted of 10 sets of Chinese monosyllables with four tone patterns for each, resulting in a total of 40 commonly used Chinese words. These original words were recorded using an adult male and an adult female native Mandarin speaker. The tone tokens in which the durations of the four tones in each monosyllable were within a 5-ms precision were chosen as the original tone tokens. These tone tokens were processed through a 16-channel chimerizer in which the FS and E of any two different tone tokens of the same syllable were swapped. For example, two tokens of the same syllable but with different tone patterns were passed through 16 band-pass filters to split each sound into 16 channels. The output of each filter was then divided into its E and FS using a Hilbert transform. Then, the E of the output in each filter band was exchanged with the E in that band for the other token to produce the single-band chimeric wave. The single-band chimeric waves were summed across all channels to generate two chimeric stimuli. Finally, a total of 320 tokens were used in the tone perception test, including 80 original unprocessed tone tokens and 240 chimeric tone tokens. A four-alternative, forced-choice procedure was used for the tone perception test. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3386

Categorization

• XREF: Auditory chimera technique connects to earlier discussions of envelope/fine-structure separation in the book’s psychoacoustics chapters. — connects to: Sequential stimulus presentation sets the JND test while simultaneous tones reveal finer differences — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 866
• DEFINE: Clearly explains the E/FS chimerization technique — swapping Hilbert-derived envelopes across channels to dissociate envelope from fine-structure cues.
• SEED: The chimerizer swap design is an elegant experimental-control template worth describing in any piece on dissociating perceptual cues.
• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3384; Dijk, Pim van, Physiology, Psychoacoustics and…, 3386