Decibel Levels

[Conrad Hoffsommer]

John,
At 08:41 12/29/2000 -0600, you wrote:
>John,
>At 08:10 12/29/2000 -0500, you wrote:
>>I'm stopping by for a few days with this question.
>>
>>Just how loud can a piano become? I have a book which says an airplane 
>>taking off will reach 140 decibels, a rock concert 120 and a snowmobile 110.
>><snip>
>
>Threshold of pain is generally agreed to be about 115-120 dB.
>
>US federal guidelines limit exposure to levels beginning at 90dBa.
>
>Years ago I measured levels while tuning and found that I could generate 
>103-105dB from medium sized grands in practice rooms, and usually well 
>into the 90's from consoles. When I get home this afternoon, I'll look up 
>the actual numbers, .........

Here goes...

Here's some old gnus.

>On Thu, 2 Feb 1995, Conrad Hoffsommer wrote:
>
> > Today's installment.
> > ..
> > I had neglected to tell you placement of meter when I was taking readings.
> > Yesterday, on the Yamaha, I had it inapproximate ear position.
> > Today on a Young Chang g-175, I got 88-93dB for temp/octaves, 98-106dBA on
> > unisons. ---I got the same readings on the stretcher, by my ear, on the
> > bench beside me, and on the bench beside me and pointed AWAY from the 
> piano.
> >
> > I think wall source has been superceded by [shall I dub it] immersion 
> source.
> > As in, there ain't no hiding from it!
> >
> > I had a wisp of a piano student play 1st mov't Beethoven Pathetique. 
> She was
> > peaking at about 96dBA on the C3 Yamaha.
> >
> > Incidentally, I went out to my vehicle, and cranked up my little old 
> 2cu.in.
> > chain saw. It idled at about 105dBA, and cranked to 117dBA no load.

Chart from OSHA regulations...

>_________________________________________________
>                                        Reference
>Aweighted sound level, L (decibel)    duration,
>                                         T (hour)
>_________________________________________________
>80...................................       32
>81...................................     27.9
>82...................................     24.3
>83...................................     21.1
>84...................................     18.4
>85...................................       16
>86...................................     13.9
>87...................................     12.1
>88...................................     10.6
>89...................................      9.2
>90...................................        8
>91...................................      7.0
>92...................................      6.1
>93...................................      5.3
>94...................................      4.6
>95...................................        4
>96...................................      3.5
>97...................................      3.0
>98...................................      2.6
>99...................................      2.3
>100..................................        2
>101..................................      1.7
>102..................................      1.5
>103..................................      1.3
>104..................................      1.1
>105..................................        1
>106..................................     0.87
>107..................................     0.76
>108..................................     0.66
>109..................................     0.57
>110..................................      0.5
>111..................................     0.44
>112..................................     0.38
>113..................................     0.33
>114..................................     0.29
>115..................................     0.25
>116..................................     0.22
>117..................................     0.19
>118..................................     0.16
>119..................................     0.14
>120..................................    0.125
>121..................................     0.11
>122..................................    0.095
>123..................................    0.082
>124..................................    0.072
>125..................................    0.063
>126..................................    0.054
>127..................................    0.047
>128..................................    0.041
>129..................................    0.036
>130..................................    0.031
>______________________________________________
>
>   In the above table the reference duration, T, is computed by
>
>                      8
>          T =
>                  2((L  90) / 5)
>
>where L is the measured Aweighted sound level.

The chart shows 8 hour exposure to 90 dBA,  ONE hour at 105 dBA.  That 
student practicing Beethoven would be limited by OSHA to just 3.5 to 4 
hours.   This is, of course, constant sound level. There are fancy meters 
which give a time weighted readout of actual exposure to varying levels, 
but the static chart should scare anybody ebough.
Conrad Hoffsommer - Luther College, Decorah, IA
Ignorance doesn't kill you, but it will make you sweat a lot.-Haitian proverb