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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# 14: Acoustics of Buildings and Acoustic Quieting"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 14.1, Page number 399"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"total absorption in hall is 825.0 OWU\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration \n",
"V=7500; #volume(m**3)\n",
"T=1.5; #time(sec)\n",
"\n",
"#Calculations\n",
"aS=0.165*V/T; #total absorption in hall(OWU)\n",
"\n",
"#Result\n",
"print \"total absorption in hall is\",aS,\"OWU\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 14.2, Page number 399"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"reverberation time when hall is empty is 2.08 sec\n",
"reverberation time with full capacity of audience is 0.362 sec\n",
"reverberation time with audience in cushioned chairs is 0.42 sec\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration \n",
"V=1500; #volume(m**3)\n",
"A1=112; #area of plastered walls(m**2)\n",
"A2=130; #area of wooden floor(m**2)\n",
"A3=170; #area of plastered ceiling(m**2)\n",
"A4=20; #area of wooden door(m**2)\n",
"n=100; #number of cushioned chairs\n",
"A5=120; #area of audience(m**2)\n",
"C1=0.03; #coefficient of absorption in plastered walls\n",
"C2=0.06; #coefficient of absorption in wooden floor\n",
"C3=0.04; #coefficient of absorption in plastered ceiling\n",
"C4=0.06; #coefficient of absorption in wooden door\n",
"C5=1.0; #coefficient of absorption in cushioned chairs\n",
"C6=4.7; #coefficient of absorption in audience\n",
"\n",
"#Calculations\n",
"a1=A1*C1; #absorption due to plastered walls\n",
"a2=A2*C2; #absorption due to wooden floor\n",
"a3=A3*C3; #absorption due to plastered ceiling\n",
"a4=A4*C4; #absorption due to wooden door\n",
"a5=n*C5; #absorption due to cushioned chairs\n",
"a6=A5*C6; #absorption due to audience \n",
"aS=a1+a2+a3+a4+a5; #total absorption in hall\n",
"T1=0.165*V/aS; #reverberation time when hall is empty(sec)\n",
"T2=0.165*V/(aS+a6); #reverberation time with full capacity of audience(sec)\n",
"T3=0.165*V/((n*C6)+aS); #reverberation time with audience in cushioned chairs(sec)\n",
"\n",
"#Result\n",
"print \"reverberation time when hall is empty is\",round(T1,2),\"sec\"\n",
"print \"reverberation time with full capacity of audience is\",round(T2,3),\"sec\"\n",
"print \"reverberation time with audience in cushioned chairs is\",round(T3,2),\"sec\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 14.3, Page number 401"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"average sound absorption coefficient is 0.24\n",
"reverberation time is 1.8 sec\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration \n",
"V=1200; #volume(m**3)\n",
"a1=220; #area of wall(m**2)\n",
"a2=120; #area of floor(m**2)\n",
"a3=120; #area of ceiling(m**2)\n",
"C1=0.03; #coefficient of absorption in wall\n",
"C2=0.80; #coefficient of absorption in floor\n",
"C3=0.06; #coefficient of absorption in ceiling\n",
"\n",
"#Calculations\n",
"A1=a1*C1; #absorption due to plastered walls\n",
"A2=a2*C2; #absorption due to wooden floor\n",
"A3=a3*C3; #absorption due to plastered ceiling\n",
"aS=a1+a2+a3; #total absorption in hall\n",
"abar=(A1+A2+A3)/aS; #average sound absorption coefficient\n",
"AS=abar*aS; #total absorption of room(metric sabines)\n",
"T=0.165*V/AS; #reverberation time(sec)\n",
"\n",
"#Result\n",
"print \"average sound absorption coefficient is\",round(abar,2)\n",
"print \"reverberation time is\",round(T,1),\"sec\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 14.4, Page number 401"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"acoustic power is 1.4e-06 watt\n",
"answer in the book is wrong\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration \n",
"I0=10**-12; #standard intensity level(watt/m**2)\n",
"A=1.4; #area(m**2)\n",
"il=60; #intensity level(decibels)\n",
"\n",
"#Calculations\n",
"x=10**(il/10);\n",
"I=x*10**-12; #intensity level(watt/m**2)\n",
"Ap=I*A; #acoustic power(watt)\n",
"\n",
"#Result\n",
"print \"acoustic power is\",Ap,\"watt\"\n",
"print \"answer in the book is wrong\""
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.11"
}
},
"nbformat": 4,
"nbformat_minor": 0
}
|
