Handbook for Sound Engineers

1252 Chapter 34

,

LR is the reverberant level in the 2 kHz octave band,
LD is the direct sound level in the 2 kHz octave band,
LN is the ambient noise level in the 2 kHz octave band.

34.2.3.4.5 Question 4: Will It Feed Back?

The PAG and NAG concepts work indoors, too, but are
modified by the room.

(34-21)

where,

,

other terms are as before.

Example:
Let,
Ds = 2 ft,
Do = 128 ft,
D 1 = 45 ft,
D 2 = 90 ft,
Dc = 31.2 ft,
NOM = 3.

To compare to the simplified (outdoor) system PAG Eq.
34-5, simply ignore the term

(34-22)

where,

,

other terms are as before.

Example:
Let

Do = 128 ft,

EAD = 4 ft,

Dc = 31.2 ft.

To compare to Eq. 34-8, simply ignore the term

Alternate forms of the PA G and NAG equations,

which are more common in the literature, follow:

(34-23)

where,

where,

x is any distance,

other terms are as before.

Example:

Let

Do = 128 ft,

D 1 = 45 ft,

Ds = 2 ft,

D 2 = 90 ft,

Q = 5,

S = 28,000 ft^2 ,

a = 0.35,

NOM = 3.

Then

and

(34-24)

where,

EN 10

LN

=^10 ------ -

PAG 20

D 0 D 1

DsD 2

log-------------– 10 logNOM

6 dB

• 
  

10

gD 0 gD (^1)
gD (^) sgD (^2)

• log------------------------------

=

gx Dc^2 += x^2

PAG 20 128 45^

290

log--------------------–6 dB 10 3log –

10 17,357 2998^

977 9073

log-----------------------------------

= –

=11.7 dB.

10

gD (^) ogD (^1)
gD (^) SgD (^2)

• log------------------------------

NAG 20

Do

EAD

log------------ 10

gD (^) o
g EAD
= – log--------------------
gx Dc^2 += x^2
NAG 20 128
4
log--------- 10 g^ 17,357
g 989
= – log------------------------
=17.7 dB
10
gD (^) o
g EAD

• log--------------------

PAG 'Do 'D 1 – 'Ds 'D 2

10

• logNOM


• 
  


• 6 dB

+=

'x 10 Q

4 Sx

----------- 2 -

4

Sa

–= log©¹§·--------+

'Do =33.6,

'D 1 =32.2,

'Ds=10.0,

'D 2 =33.4,

PAG 33.6+= 33.2 10– –633.4 10–3log – dB

=11.7 dB

NAG 'Do–= 'EAD