Table 1:
Examples of underwater noise levels related mainly to the ship traffic in the global seas and oceans.
| Location, depth of the hydrophone and depth of the sea water | Year of study | Underwater noise levels at different frequencies | Location, depth of the hydrophone and depth of the sea water | Year of study | Underwater noise levels at different frequencies |
|---|---|---|---|---|---|
| Scotian Shelf, Canada, hydrophone depth of 31 m and water depth of 79 m [3] | 1972–1985 | Winter average noise levels at zero wind speed [3]: 30 Hz: 90.8 dB re μPa2/Hz 45 Hz: 90.5 dB re μPa2/Hz 80 Hz: 87.9 dB re μPa2/Hz 150 Hz: 81.9 dB re μPa2/Hz 300 Hz: 74.1 dB re μPa2/Hz 600 Hz: 64.4 dB re μPa2/Hz 900 Hz: 64.3 dB re μPa2/Hz | Ramsey Sound, Pembrokeshire, West Wales, UK, hydrophone depth of 20 m and a water depth of 460 m [7] | 2009 | Sound pressure levels [7]: Between 5 Hz and 10 Hz:
|
| India, shallow water, hydrophone depth of 5 m and water depth of 25 m [4] | 2006 | Average noise levels [4]: 98 Hz: 130.3 dB re μPa/√Hz 195 Hz: 128.6 dB re μPa/√Hz 293 Hz: 127.3 dB re μPa/√Hz 586 Hz: 127.6 dB re μPa/√Hz 977 Hz: 127.4 dB re μPa/√Hz 3027 Hz: 127.1 dB re μPa/√Hz 4023 Hz: 127.1 dB re μPa/√Hz | Guanabara Bay, SE Brazil, hydrophone depth of 2 m and a water depth of 4 m [8] | 2011–2012 | The highest mean sound pressure level [8]): At 187 Hz: 111.6 ± 9.0 dB re 1 μPa At 15.89 kHz: 76.2 ± 8.3 dB re 1 μPa |
| Indian Ocean, the lagoon of a coral atoll, hydrophone depth of 2–15 m and water depth of 50 m [5] | 2005 | Spectral maxima observed at 1 kHz and 7.5 kHz [5]: 1,000 Hz: 72 dB re μPa/√Hz 2,000 Hz: 65 dB re μPa/√Hz 7,500 Hz: 80 dB re μPa/√Hz | Port of South Louisiana (H-3), Port of Houston (H-1), NE Gulf of Mexico, hydrophone depth from 250–1,370 m [9] | 2010–2012 | The highest values L01 (T = 1 h) at two sites (H-3 and H-1) nearest to high-shipping lanes [9] in LF band (10–500 Hz) were: 130 dB re 1 μPa and 128 dB re 1 μPa, respectively (L01 = sound levels that were exceeded 1% of the time) |
| Northeast Pacific Ocean, SW of the San Nicolas Island, California, USA, hydrophone depth of 1,090–1,106 m [6] | 1966 – 2006 | Mean ambient noise levels: −30–50 Hz in 1964–1966: 73–75 dB re 1 Pa2/Hz −30–50 Hz in 2003–2004: 85 dB re 1 Pa2/Hz [6] | Celtic Sea, northern and southern North Sea in UK, hydrophone depth of 100 m and a water depth of 200 m [10] | 2013–2014 | Median noise levels for 1/3 octave bands from 63 Hz to 500 Hz [10]: 81.5–95.5 dB re 1μPa |
Table 2:
The Pearson correlation coefficients between the dependent variable (Leq,63Hz) and the independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice., dreadg. act., clean. act., vv and hp) in all measuring periods.
| Pearson's correlation coefficient | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| r (vv) | 0.58 | 0.51 | 0.54 | 0.39 | 0.35 |
| r (hp) | −0.02 | 0.06 | 0.08 | 0.08 | 0.07 |
| r (ρL,2NM) | 0.13 | −0.06 | 0.05 | −0.04 | 0.05 |
| r (ρL,5NM) | 0.06 | −0.06 | 0.02 | 0.09 | 0.08 |
| r (ρL,Trieste) | −0.02 | −0.03 | 0.08 | 0.12 | 0.12 |
| r (ρL,Venice) | −0.10 | −0.05 | −0.05 | 0.01 | −0.11 |
| r (dredg. act.) | n.a. | 0.31 | n.a. | n.a. | n.a. |
| r (clean. act.) | n.a. | n.a. | −0.10 | n.a. | n.a. |
Table 3:
The Pearson correlation coefficients between the dependent variable (Leq,125Hz) and the independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice, dreadg. act., clean. act., vv and hp) in all measuring periods.
| Pearsons correlation coefficients | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| r (vv) | 0.39 | 0.18 | 0.55 | 0.24 | 0.15 |
| r (hp) | −0.02 | 0.01 | 0.09 | 0.04 | 0.02 |
| r (ρL,2NM) | 0.11 | 0.06 | 0.07 | 0.02 | 0.12 |
| r (ρL,5NM) | 0.05 | 0.05 | −0.04 | 0.17 | 0.02 |
| r (ρL,Trieste) | −0.02 | 0.02 | 0.01 | 0.18 | 0.04 |
| r (ρL,Venice) | −0.08 | −0.01 | −0.09 | −0.01 | −0.10 |
| r (dredg. act.) | n.a. | 0.10 | n.a. | n.a. | n.a. |
| r (clean. act.) | n.a. | n.a. | −0.10 | n.a. | n.a. |
Table 4:
Multiple correlation coefficients (r) between dependent variables (Leq,63Hz and Leq,125Hz) and independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice, dreadg. act., clean. act., vv and hp) in all measuring periods.
| Multiple correlation coefficients | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| r (Leq,63Hz) | 0.59 | 0.55 | 0.57 | 0.40 | 0.40 |
| r (Leq,125Hz) | 0.41 | 0.21 | 0.59 | 0.29 | 0.23 |
Table 5:
Coefficients of determination (R2) between the dependent variables (Leq,63Hz and Leq,125Hz) and the independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice, dreadg. act., clean. act., vv and hp) in all measuring periods.
| Coefficients of determination | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| R2 (Leq,63Hz) | 0.35 | 0.30 | 0.33 | 0.16 | 0.16 |
| R2 (Leq,125Hz) | 0.17 | 0.05 | 0.34 | 0.09 | 0.05 |
Table 6:
Significant independent variables with p-values lower than 0.05, meaning that there was a more than 95 % probability that these variables were related to the dependent variable Leq,63Hz. The grey fields indicate insignificant independent variables, with p-values greater than 0.05. The abbreviation n.a. means not applicable.
| p-values | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| p (vv) | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 |
| p (hp) | 0.001 | 0.061 | 0.240 | 0.923 | 0.010 |
| p (ρL,2NM) | 0.005 | 0.691 | 0.048 | 0.003 | 0.036 |
| p (ρL,5NM) | 0.007 | 0.015 | 0.000 | 0.556 | 0.000 |
| p (ρL,Trieste) | 0.327 | 0.794 | 0.000 | 0.119 | 0.000 |
| p (ρL,Venice) | 0.037 | 0.087 | 0.023 | 0.342 | 0.000 |
| p (dredg. act.) | n.a. | 0.000 | n.a. | n.a. | n.a. |
| p (clean. act.) | n.a. | n.a. | 0.002 | n.a. | n.a. |
Table 7:
Significant independent variables with p-values less than 0.05, meaning that there was a more than 95 % probability that these variables were related to the dependent variable Leq,125Hz. The grey fields indicate insignificant independent variables with p-values greater than 0.05. The abbreviation n.a. means not applicable.
| p-values | From 13.02.2015 to 05.05.2015 | From 26.09.2015 to 31.12.2015 | From 18.08.2016 to 01.11.2016 | From 06.07.2017 to 07.08.2017 | From 18.08.2018 to 31.12.2018 |
|---|---|---|---|---|---|
| p (vv) | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 |
| p (hp) | 0.019 | 0.509 | 0.111 | 0.867 | 0.599 |
| p (ρL,2NM) | 0.097 | 0.022 | 0.000 | 0.033 | 0.000 |
| p (ρL,5NM) | 0.000 | 0.000 | 0.000 | 0.215 | 0.002 |
| p (ρL,Tireste) | 0.001 | 0.000 | 0.000 | 0.033 | 0.000 |
| p (ρL,Venice) | 0.256 | 0.110 | 0.036 | 0.000 | 0.000 |
| p (dredg. act.) | n.a. | 0.000 | n.a. | n.a. | n.a. |
| p (clean. act.) | n.a. | n.a. | 0.021 | n.a. | n.a. |
Table 8:
Regression equations in which the dependent variable Leq,63Hz was predicted by the significant independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice, dreadg. act., clean. act., vv and hp).
| Measuring periods | Regression equations |
|---|---|
| 13.02.2015–05.05.2015 | Leq,63Hz = 1.378*vv − 3.898*hp + 0.357*ρL,2NM + 0.103*ρL,5NM – 0.014*ρL,Venice + 63.450 |
| 26.09.2015–31.12.2015 | Leq,63Hz = 1.117*vv − 0.093*ρL,5NM + 4.304*dred.act. + 67.800 |
| 18.08.2016–01.11.2016 | Leq,63Hz = 2.227*vv + 0.165*ρL,2NM – 0.627*ρL,5NM + 0.528*ρL,Trieste – 0.012*ρL,Venice – 3.1*clean.a. + 81.77 |
| 06.07.2017–07.08.2017 | Leq,63Hz = 2.762*vv − 0.196*ρL,2NM + 70.065 |
| 18.08.2018–31.12.2018 | Leq,63Hz = 1.555*vv + 1.116*hp + 0.112*ρL,2NM − 0.216*ρL,5NM + 0.268*ρL,Trieste – 0.022*ρL,Venice + 73.576 |
Table 9:
Regression equations in which the dependent variable Leq,125Hz was predicted by the significant independent variables (ρL,2NM, ρL,5NM, ρL,Trieste, ρL,Venice, dreadg. act., clean. act., vv and hp).
| Measuring periods | Regression equations |
|---|---|
| 13.02.2015–05.05.2015 | Leq,125Hz = 0.752*vv − 2.659*hp + 0.263*ρL,5NM – 0.153*ρL,Trieste + 77.786 |
| 26.09.2015–31.12.2015 | Leq,125Hz = 0.248*vv + 0.192*ρL,2NM + 0.167*ρL,5NM – 0.117*ρL,Trieste + 1.181*dred. + 77.375 |
| 18.08.2016–01.11.2016 | Leq,125Hz = 1.869*vv + 0.265*ρL,2NM – 0.551*ρL,5NM + 0.368*ρL,Trieste – 0.009*ρL,Venice – 1.87* clean.a. + 84.6 |
| 06.07.2017–07.08.2017 | Leq,125Hz = 1.063*vv − 0.122*ρL,2NM + 0.151*ρL,Triestre – 0.017*ρL,Venice + 71.912 |
| 18.08.2018–31.12.2018 | Leq,125Hz = 0.562*vv + 0.364*ρL,2NM − 0.126*ρL,5NM + 0.121*ρL,Trieste – 0.017*ρL,Venice + 91.705 |