TABLE II.

More channels in the vocoded signal will often result in stronger perceptual and processing outcomes. However, the number of channels required for saturation varies by outcome. Note: research presented is not comprehensive. Only results from monolingual adult listeners with NH are included. When multiple SNRs were studied, performance at 0-dB SNR is reported. PRT = phoneme recognition threshold; FFR = frequency following response.

Author (year)	Num. of channels	Stimuli	Outcome	Channels required for saturation
Dorman et al. (1997b)	2, 3, 4, 5, 6, 7, 8, 9	Iowa vowels	% vowels correct	6
		Synthetic b/V/t words	% vowels correct	8
		Multitalker vowels	% vowels correct	8
		h/V/d words	% vowels correct	8
		a/C/a syllables	% consonants correct	6
			% place info transmitted	6
			% manner info transmitted	2
			% voicing info transmitted	3
		HINT sentences	% words correct	5
Shannon et al. (1998)	1, 2, 3, 4	h/V/d words	% vowels correct	Not attained
		a/C/a syllables	% consonants correct	Not attained
			% place info transmitted	Not attained
			% manner info transmitted	2
			% voicing info transmitted	3
		Sentences	% words correct	Not attained
Fu and Shannon (1999)	4, 8, 16	h/V/d words	% vowels correct	Not attained
Loizou et al. (1999)	2, 3, 4, 5, 6, 8, 10, 12	TIMIT sentences	% words correct	8
Friesen et al. (2001)	2, 4, 6, 8, 12, 16, 20	h/V/d words	PRT	16
		a/C/a words	PRT	16
		HINT sentences	PRT	12
Gonzalez and Oliver (2005)	3, 4, 5, 6, 8, 10, 12, 16	Sentences	Gender identification	10
	3, 4, 8, 16	Sentences	Speaker identification	Not attained
Xu et al. (2005b)	1, 2, 3, 4, 6, 8, 12, 16	h/V/d words	% vowels correct	12
		C/a/ syllables	% consonants correct	8
Başkent (2006)	2, 4, 6, 8, 10, 12, 16, 24, 40	h/V/d words	% vowels correct	8
		a/C/a syllables	% consonants correct	8
Winn et al. (2015)	4, 8, 16, 32	IEEE sentences	Rate and size of pupillary response in key analysis window	Not attained
Ananthakrishnan et al. (2017)	1, 2, 4, 8, 16, 32	/u/	FFR	8