Table 2.
ABR threshold shifts observed up to 12 months post-exposure to 105 dB Noise.
| Recovery | 1 DPN | 3 DPN | 7 DPN | 14 DPN | 28 DPN | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hz | M | SE | M | SE | M | SE | M | SE | M | SE | ||||||
| Hypo. Control | Ck | 1.0 | 2.4 | −5.0 | 1.6 | −5.0 | 1.6 | −1.0 | 1.9 | 2.0 | 1.2 | |||||
| 2 k | 3.0 | 2.5 | −1.0 | 1.9 | −1.0 | 1.9 | −1.0 | 2.9 | 2.0 | 2.5 | ||||||
| 4 k | 2.0 | 3.0 | 2.0 | 2.5 | 3.0 | 3.4 | 6.0 | 2.9 | 3.0 | 3.0 | ||||||
| 8 k | 2.0 | 2.0 | 4.0 | 1.9 | 3.0 | 2.5 | 7.0 | 3.4 | 5.0 | 1.6 | ||||||
| 16 k | −3.0 | 3.0 | 2.0 | 3.4 | 3.0 | 3.0 | 2.0 | 4.9 | −1.0 | 1.9 | ||||||
| 24 k | 4.0 | 1.0 | 3.0 | 1.2 | 0.0 | 1.6 | 4.0 | 1.9 | 1.0 | 1.9 | ||||||
| 32 k | −4.0 | 1.0 | −5.0 | 1.6 | −7.0 | 4.1 | −1.0 | 2.4 | −2.0 | 3.0 | ||||||
| Noise + Normo. | Ck | 20.0 | 7.4 | ** | 8.0 | 5.1 | 11.0 | 2.9 | 11.0 | 1.9 | 6.0 | 1.0 | ||||
| 2 k | 17.5 | 7.5 | * | 11.0 | 7.0 | 10.0 | 6.3 | 8.0 | 4.6 | 9.0 | 4.8 | |||||
| 4 k | 18.8 | 9.0 | ** | 9.0 | 3.7 | 5.0 | 3.5 | 6.0 | 1.9 | 2.0 | 3.0 | |||||
| 8 k | 45.0 | 7.4 | ** | 27.0 | 7.2 | ** | 21.0 | 6.2 | ** | 18.0 | 4.1 | ** | 5.0 | 3.5 | ||
| 16 k | 46.3 | 7.5 | ** | 25.0 | 9.9 | ** | 17.0 | 6.4 | * | 16.0 | 6.6 | * | 3.0 | 4.4 | ||
| 24 k | 56.3 | 6.6 | ** | 20.0 | 6.1 | ** | 15.0 | 5.5 | 11.0 | 2.9 | 5.0 | 3.2 | ||||
| 32 k | 53.8 | 8.3 | ** | 27.0 | 7.3 | ** | 22.0 | 6.4 | ** | 12.0 | 4.1 | 4.0 | 3.7 | |||
| Noise + Hypo. | Ck | 9.0 | 3.3 | ** | 2.0 | 4.6 | 2.0 | 4.1 | −1.0 | 4.6 | 1.0 | 2.4 | ||||
| 2 k | 4.0 | 6.8 | ** | 3.0 | 6.0 | 1.0 | 4.8 | 3.0 | 5.8 | 3.0 | 5.1 | |||||
| 4 k | 6.0 | 3.7 | ** | 2.0 | 4.6 | 6.0 | 4.8 | 0.0 | 2.2 | −2.0 | 2.5 | |||||
| 8 k | 11.0 | 7.0 | ** | 6.0 | 6.6 | 2.0 | 6.0 | 6.0 | 5.8 | 2.0 | 3.4 | |||||
| 16 k | 9.0 | 5.6 | ** | 0.0 | 4.5 | −3.0 | 5.4 | 0.0 | 4.7 | −2.0 | 3.4 | |||||
| 24 k | 14.0 | 6.2 | ** | 4.0 | 5.8 | 7.0 | 4.6 | 5.0 | 3.5 | 1.0 | 2.9 | |||||
| 32 k | 16.0 | 7.0 | ** | 8.0 | 6.6 | 1.0 | 3.7 | 4.0 | 4.0 | 1.0 | 2.4 | |||||
| Aging | 2 MPN | 3 MPN | 6 MPN | 9 MPN | 12 MPN | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hz | M | SE | M | SE | M | SE | M | SE | M | SE | ||||||
| Hypo. Control | Ck | −4.0 | 2.9 | −6.0 | 2.4 | −6.0 | 2.9 | −5.0 | 2.9 | 5.0 | 2.7 | |||||
| 2 k | 0.0 | 1.6 | 8.0 | 1.2 | 2.0 | 2.0 | 3.3 | 1.7 | 4.0 | 2.4 | ||||||
| 4 k | 3.0 | 3.4 | 5.0 | 4.2 | 8.0 | 2.0 | 5.0 | 7.6 | 6.0 | 1.9 | ||||||
| 8 k | 2.0 | 4.1 | 1.0 | 3.3 | 0.0 | 2.2 | −3.3 | 1.7 | 1.0 | 2.9 | ||||||
| 16 k | 3.0 | 5.6 | 4.0 | 2.9 | 2.0 | 3.7 | 3.3 | 6.0 | −3.0 | 4.4 | ||||||
| 24 k | 7.0 | 1.2 | 5.0 | 1.6 | 1.0 | 2.9 | 0.0 | 0.0 | 2.0 | 1.2 | ||||||
| 32 k | −5.0 | 2.7 | −1.0 | 2.4 | −5.0 | 0.0 | −3.3 | 1.7 | −6.0 | 2.9 | ||||||
| Noise + Normo. | Ck | 3.0 | 3.4 | −1.1 | 2.9 | 4.0 | 1.9 | 5.0 | 4.6 | 13.0 | 2.0 | |||||
| 2 k | 4.0 | 6.6 | −1.0 | 5.3 | 10.0 | 2.2 | 8.8 | 5.5 | 17.0 | 3.4 | * | |||||
| 4 k | 0.0 | 2.2 | −1.0 | 1.0 | 0.0 | 0.0 | 5.0 | 2.0 | 9.0 | 3.7 | ||||||
| 8 k | 6.0 | 5.1 | 5.0 | 4.2 | 5.0 | 2.2 | 5.0 | 4.6 | 19.0 | 6.0 | ** | |||||
| 16 k | 7.0 | 3.4 | 4.0 | 1.9 | 8.0 | 3.0 | 6.3 | 2.4 | 8.0 | 3.4 | ||||||
| 24 k | −3.0 | 3.4 | 2.0 | 3.4 | 1.0 | 3.7 | −3.8 | 3.8 | 7.0 | 4.1 | ||||||
| 32 k | 5.0 | 3.2 | 3.0 | 2.5 | 9.0 | 2.9 | 7.5 | 1.4 | 15.0 | 4.2 | ||||||
| Noise + Hypo. | Ck | −3.0 | 4.4 | −7.0 | 6.0 | −6.0 | 4.6 | 1.3 | 4.3 | 6.0 | 4.0 | |||||
| 2 k | 0.0 | 5.7 | −2.0 | 5.6 | −4.0 | 3.7 | 0.0 | 3.5 | 6.0 | 5.8 | ||||||
| 4 k | −1.0 | 2.9 | 3.0 | 4.1 | 2.0 | 2.5 | −3.8 | 4.3 | 9.0 | 5.8 | ||||||
| 8 k | 1.0 | 4.0 | 0.0 | 4.5 | 0.0 | 1.6 | −6.3 | 6.9 | 8.0 | 5.8 | ||||||
| 16 k | −4.0 | 2.4 | −5.0 | 1.6 | −5.0 | 2.2 | −6.3 | 1.3 | 0.0 | 5.9 | ||||||
| 24 k | 3.0 | 3.4 | 1.0 | 2.9 | 2.0 | 2.0 | −2.5 | 2.5 | 1.0 | 3.3 | ||||||
| 32 k | 3.0 | 2.5 | 3.0 | 2.0 | 1.0 | 3.3 | −1.3 | 2.4 | 3.0 | 3.4 | ||||||
Significance level.
** < 0.01, * < 0.05.
Summary of ABR threshold shifts from baseline obtained before and after exposure to 2 h of 105 dB noise. Results of mean ± SE ABR threshold shifts for hypothermia control, noise+normothermia, and noise+hypothermia animals are shown for all tested stimuli (click, 2–32 kHz). In addition, group-specific statistical differences from baseline measurements were obtained at 1, 3, 7, 14, and 28 DPN within the acute recovery phase (tan) and at 2, 4, 6, 9, and 12 MPN for the early aging phase (blue). Differences from baseline are expressed for each frequency and time point (*p < 0.05, **p < 0.01). Significant values in bold. ABR Threshold Shifts up to 12 MPN. dB, decibels; Normo, Normothermia; Hypo, Hypothermia; DPN, days post-noise; Ck, Click; Mean ± SE.