Issue 50

A. Kakaliagos et alii, Frattura ed Integrità Strutturale, 50 (2019) 481-496; DOI: 10.3221/IGF-ESIS.50.40 488 Psychological i mpact - Sound effect of Orban’s gun The peak blast overpressure corresponding to the rise of atmospheric pressure inside the gun was converted to an equivalent sound pressure level P SPL measured in dB. The sound pressure level P SPL was computed at 254 dB using the atmospheric pressure P atm =101,325 Pa together with R=1,000 and P 0 =2x10 -5 N/m 2 the reference sound pressure level at zero dB (Eq.(9)). Sound pressure level decay was captured with Eq.(10), whereby, L 1 is the sound pressure at distance r 1 from blast source and L 2 the corresponding sound pressure at distance r 2 respectively. ௌ௉௅ ൌ 20 ቀ ோ௉ ೌ೟೘ ௉ బ ቁ (9) ଶ ൌ ଵ െ ቚ20 ቀ ௥ భ ௥ మ ቁቚ (10) Decibel (dB) units of sound pressure level are atmospheric decibels and, therefore, do not necessarily express what the listener would experience. However, they serve as indication in order to evaluate a sound impact on the human ear (Table 5). Sound pressure level at various Constantinople locations was computed (Fig.3). Results confirm reports whereby Orban’s gun could be heard even at a distance of 40 Stadia (Chalkokondyles [2]). Sound pressure at St. Romanus Gate and at the Mesotechion portion of the Theodosian Walls was at 120 dB, value extremely high for the human ear (Iskanter [5]). In Constantinople, sound pressure level was extremely disturbing for the human ear and was in the range of 100-110dB, with sound pressure level at Aghia Sofia at 100 dB. It can be understood that people inside the City were afraid and women fainted due to the cannon roar (Phrantzes [6], Barbaro [1]). Sound pressure level (dB) Effect on human ear 30 Totally quiet nighttime in desert 85 Beginning of hearing damage, earplugs should be worn 100 Normal average car or house stereo at maximum volume 104-107 The beginning of pain at the most sensitive frequency of 2750 Hertz 107-114 A very large, powerful portable radio 116 Human body begins to perceive vibration in the low frequencies 120 200 Front row in rock concert F16 sonic boom 235 Earthquake intensity 5 on Richter scale Table 5: Sound pressure level effect on human ear. # Location Sound pressure level (dB) 1 St. Romanus Gate 120 2 Phanarion 108 3 Vlachernae Palace 106 4 Column of Marcian 105 5 Golden Gate 103 6 Forum Theodosius 102 7 Galata Tower 101 8 Forum Constantine 101 9 Aghia Sofia 100 10 Diplokionion 98 11 At 40 Stadia, 7.5 km distance from Blast 97 Figure 3: Orban’s gun sound pressure level.