{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 2: Acoustics of Buildings"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.1, Page 52"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log10\n",
"\n",
"#Variable Declaration\n",
"#delta_L=L2-L1\n",
"\n",
"#Calculation\n",
"#I proportional to square of amplitude so when amplitude is doubled intensity will becomes 4 times \n",
"#L1=10*l0g10(I1/I0)\n",
"#L2=10*log10(I2/I0)\n",
"#delta_L=L2-L1\n",
"#delta_L=10*log(I1/I0)-10*log(I2/I0)=10*log(I2/I1)\n",
"I21=4;#I2/I1=4 because intensity=amp^2\n",
"delta_L=10*log10(I21);#increase in intensity level\n",
"\n",
"#Result\n",
"print 'Increase in intensity level =',round(delta_L,2),'dB'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Increase in intensity level = 6.02 dB\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.2, Page 52"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt\n",
"\n",
"#Variable Declaration\n",
"#L2-L1=10*log10(I2/I1)\n",
"#so , we can write that \n",
"L2=40 #i dB\n",
"L1=10 #in dB \n",
"#where L1 and L2 are intensity level of two waves of same frequency\n",
"\n",
"#Calculation\n",
"L=L2-L1;\n",
"#let I2/I1=I\n",
"I=10**(L/10);\n",
"#let a2/a1=a\n",
"a=sqrt(I);#Ratio of their amplitudes \n",
"\n",
"#Result\n",
"print 'Ratio of their amplitudes =',round(a,3)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Ratio of their amplitudes = 31.623\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.3, Page 53"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log10\n",
"\n",
"#Variable Declaration\n",
"I1=25.2 #in Wm^-2\n",
"I2=0.90 #in Wm^-2\n",
"\n",
"#Calculation\n",
"B=10*log10(I1/I2) #Relative loudness of sound in dB\n",
"\n",
"#Result\n",
"print 'Relative loudness of sound = ',round(B,2),'dB'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Relative loudness of sound = 14.47 dB\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.4, Page 53"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log10\n",
"\n",
"#Variable Declaration\n",
"I=1e4 #in W/(m*m)\n",
"I0=1e-12 #in W/(m*m)\n",
"\n",
"#Calculation\n",
"B=10*log10(I/I0);#intensity level\n",
"\n",
"#Result\n",
"print \"intensity level = \",B,'dB'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"intensity level = 160.0 dB\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.5, Page 54"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"B=5 # in dB\n",
"\n",
"#Calculation\n",
"#B=10*log(I2/I1)\n",
"#let I2/I1=x\n",
"#10*log(x)=5\n",
"x=10**(5./10);\n",
"\n",
"#Result\n",
"print 'Amplified sound is',round(x,3),'times more intense than the unamplified sound'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Amplified sound is 3.162 times more intense than the unamplified sound\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.6, Page 57"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"d=198; #in meter\n",
"t=1.2;#in second\n",
"\n",
"#Calculation\n",
"#velocity=distance/time\n",
"v=2*d/t;#velocity\n",
"\n",
"#Result\n",
"print 'velocity =',v,'m/s'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"velocity = 330.0 m/s\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.7, Page 64"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"V=5600 #in m^3\n",
"T=2 #in second\n",
"s=700 #in m^2\n",
"\n",
"#Calculation\n",
"a=0.16*V/(s*T)\n",
"\n",
"#Result\n",
"print \"absorption coefficient =\",a\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"absorption coefficient = 0.64\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.8, Page 65"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"absorp1=92.90; #in m^^2\n",
"absorp2=92.90;#in m^2\n",
"V=2265.6;#in m^3\n",
"\n",
"#Calculations\n",
"T1=0.16*V/(absorp1);\n",
"T2=0.16*V/(absorp1+absorp2);\n",
"ans=T2/T1;#effect on Reverberation time\n",
"\n",
"#Result\n",
"print \"Reverberation time reduced to \",ans,\"of original value\"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Reverberation time reduced to 0.5 of original value\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.9, Page 65"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"v=25.2*20.3*8.04 ;#in m^3\n",
"T=0.75; #in second\n",
"\n",
"#Calculations\n",
"absorp1=500*0.3176 ;#in m^2\n",
"absorp2=(0.16*v)/T;\n",
"T1=(0.16*v)/(absorp1+absorp2);#reverbaration time\n",
"\n",
"#Result\n",
"print \"reverbaration time =\",round(T1,3),'sec'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"reverbaration time = 0.635 sec\n"
]
}
],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2.10, Page 66"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable Declaration\n",
"v=45*100*17.78;#in m^3\n",
"\n",
"#Calculations\n",
"absorp1=(700*0.03)+(600*0.06)+(400*0.025)+(600*0.3);\n",
"absorp_p=600*4.3;\n",
"T1=(0.16*v)/(absorp1);#Reverbaration time (empty hall) \n",
"T2=(0.16*v)/(absorp_p+absorp1);#Reverbaration time with full capacity\n",
"\n",
"#Results\n",
"print 'Reverbaration time (empty hall) =',round(T1,2),'sec' #printing mistake at the end in the textbook\n",
"print 'Reverbaration time with full capacity =',round(T2,2),'sec'"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Reverbaration time (empty hall) = 51.83 sec\n",
"Reverbaration time with full capacity = 4.53 sec\n"
]
}
],
"prompt_number": 12
}
],
"metadata": {}
}
]
}