Table 4.

Frequency compression.

Citation	Comparison	Acclimatization	Outcome category	Measure	Sub-measure	Effect size [95% CI]a	p value
Glista et al. (2009)	NLFC CP	NLFC: Avg. 10.75 wks   (range 3 wks–1.3 yrs) CP: Avg. 4.17 wks   (range 2 wks–3 mnths)	Audibility	Aided   thresholds	Phonemes /s/ and /sh/	NR/NC	Group analysis: NRb Individual analysis:   2/10 participants: p < .05   (favors NLFC for at   least one phoneme,   /s/ or /sh/) 8/10 participants: NS
		User was able to activate/   deactivate NLFC in   final phase: Avg. 5.58 wks   (range 2 wks to 5 mnths)	Speech   recognition	Speech recognition   test	Consonants	NR/NC	Group analysis: NRb Individual analysis:   4/10 participants   p < .05 (favors NLFC);   6/10: NS
					Vowels	NR/NC	Group analysis: NRb Individual analysis:   11/11 participants: NS
					Plurals	NR/NC	Group analysis: NRb Individual analysis:   7/11 participants:   p < .05 (favors NLFC);   4/11: NS
Wolfe et al. (2010, 2011	NLFC CP	NLFC: 6 wks CP: 6 wks	Audibility	Aided thresholds	Overall	r = .82 [.53, .94]c	p < .001 (favors NLFC)
					4000 Hz 6000 Hz 8000 Hz Phoneme /s/ Phoneme /sh/	r = .68 [.26, .88]c r = .76 [.41, .92]c r = .58 [.10, .84]c r = .87 [.65, .96]c r = .60 [.13, .85]c	p < .01 (favors NLFC) p < .01 (favors NLFC) p < .05 (favors NLFC) p < .001 (favors NLFC) p < .05 (favors NLFC)
			Speech   recognition	Speech recognition   test	Plurals	r = .81 [.51, .93]c	p < .001 (favors NLFC; ceiling effects for 2 children)
				Phoneme discrimination thresholds:	Token /asa/ Token /ada/ Token /afa/ Token /aka/ Token /asha/ Token /ata/ Token /asa/ filtered   at 6000 Hz	r = .57 [.03, .85]c r = .56 [.07, .83]c NR/NC NR/NC NC NR/NC r = .52 [–.04, .83]c r = .28 [–.29, .71]c	p < .05(favors NLFC) p < .05 (favors NLFC) NS NS NS NS NS
				Sentences in noise test		r = .35 [–.20, .73]c	NS

Note. Avg = average; CP = conventional processing; CI = confidence interval; Hz = Hertz; mnths = months; NLFC = nonlinear frequency compression; NC = not calculable; NR = not reported; NS = not significant; wks = weeks; yrs = years.

^aPositive effect sizes indicate that the direction of effect favors frequency compression. Negative effect sizes indicate that the direction of the effect favors conventional processing,

^bRepeated measures ANOVA completed with combined adult/child data and age group included as between-subjects variable, however results not presented for separate analysis of child data,

^cEffect size, r, calculated using the paired-samples t test statistic and df provided in the study.