Table 2.

Clinical Question 1: Comparison of compression limiting versus peak clipping on speech recognition outcomes.

Citation	Condition	Compression settings	Stimuli	Open/closed set	Presentation level/SNR	Effect size	p
Christensen (1999)	Linear CL	Threshold: high 75 dB Attack time: 5 ms Release time: adjustable up to 1 s Ratio: 8:1 Volume control: listener unable to adjust during testing	Bisyllabic spondaic words	Open	50, 65, and 80 dB SPL/quiet, +5, +10 SNR	NR/NC	ns across SNRs
			Passages	Open	50, 65, and 80 dB SPL/quiet, +5, +10 SNR	NR/NC	ns across SNRs
			Sentences	Open	53 and 83 dB SPL (70 dB HL)/0, +5, +10, +15 SNR	NR/NC	ns across SNRs
	Linear PC	Threshold: none Attack time: instantaneous Release time: instantaneous Ratio: none Volume control: listener unable to adjust during testing
Marriage et al. (2005)	Linear CL	Threshold: high Attack time: 0.5 ms Release time: 50 ms Ratio: NR Volume control: NR	Monosyllabic words (profound HL)	Closed	50, 65, and 80 dBA/quiet	NR/NC	ns
			Monosyllabic words (severe HL)	Closed	45 dBA quiet/50 dBA noise	NR/NC	ns
			Words (profound HL)	Open	50, 65, and 80 dBA/quiet	NR/NC	ns
			Words (severe HL)	Open	45 and 80 dBA in quiet 50 dBA noise	NR/NC	ns
	Linear PC	Threshold: high Attack time: 0.5 ms Release time: 5 ms Ratio: NR Volume control: NR	Sentences SNR (severe HL)	Open	In 60 dB modulated noise	NR/NC	ns
			Common phrases (profound HL)	Open	80 dBA/quiet	NR/NC	ns

Note. SNR = signal-to-noise ratio; CL = compression limiting; SPL = sound pressure level; NC = not calculable; PC = peak clipping.