Protection by the uncrossed efferent pathways from loud sound-induced threshold shifts in a noise background can be elicited by monaural stimulation
| Comparison groups/treatments4-a | ANOVAF and p values (Interaction = group × frequency interaction) | t test type4-b and df4-c | Frequency range with significant differences4-d and parameters of significance | |
|---|---|---|---|---|
| A. Cochlear protection from loud sound-induced TTS can be elicited by monaural loud sound in a monaural noise background | ||||
| Silence 1 (OC+) | Noise 6 (OC+) | GroupF = 0.185; p > 0.6 | ||
| Monaural exposure | Monaural exposure in noise | Interaction F = 1.028; p = 0.4 | ||
| Noise 3 OC− | Noise 6 (OC+) | Group F = 25.44; p < 0.001 | One-tail, df = 10 | 12–28 kHz; t always > 2.06; pgenerally p < 0.01 |
| Binaural exposure in noise | Monaural exposure in noise | Interaction F = 6.022; p < 0.001 | ||
| B. Cochlear protection from loud sound-induced TTS elicited in the monaural condition is attributable to only the uncrossed efferent pathways | ||||
| Noise 6 (OC+) | Noise 7 OC− | GroupF = 42.22; p < 0.001 | One-tail, df = 9 | 9–28 kHz; t always > 2.65; p generally < 0.005 |
| Monaural exposure in noise | Monaural exposure in noise | Interaction F = 8.51; p < 0.001 | ||
| Noise 7 COC− | Noise 7 OC− | Group F = 111.7; p < 0.001 | One-tail, df = 8 | 10–28 kHz;t always > 2.43; p generally < 0.005 |
| Monaural exposure in noise | Monaural exposure in noise | Interaction F = 12.34; p < 0.001 | ||
| Noise 6 (OC+) | Noise 7 COC− | Group F = 0.068; p = 0.8 | ||
| Monaural exposure in noise | Monaural exposure in noise | Interaction F = 0.53; p = 0.9 | ||
| C. Cochlear protection obtained through the uncrossed efferent pathways in the monaural condition is not as large as the cochlear protection obtained through crossed and uncrossed efferent pathways in the binaural condition | ||||
| Noise 7 COC− | Noise 3 OC+ | Group F = 6.57; p < 0.05 | One-tail, df = 9 | 11–16 kHz; t always > 2.29; pgenerally < 0.01 |
| Monaural exposure in noise | Binaural exposure in noise | Interaction F = 1.33; p = 0.18 | ||
| Noise 7 COC− | Noise 4 (COC−) | Group F = 0.018; p = 0.9 | ||
| Monaural exposure in noise | Binaural exposure in noise | Interaction F = 0.58; p = 0.9 | ||
↵F4-a Noise 6 and 7 were tested with the loud tone monaurally in a background of monaural ipsilateral noise at 80 dB SPL. OC+ = all olivocochlear efferent pathways were intact to that group/treatment ears, OC− = all efferent pathways were lesioned, and COC− = only the crossed efferent pathways lesioned (leaving uncrossed efferent pathways intact).
↵F4-b t tests were performed when the ANOVA indicated significant differences.
↵F4-c Degrees of freedom.
↵F4-d Frequencies for which tvalues were significant at α = 0.05 (i.e., p at least < 0.05).