G.R.A.S. SOUND & VIBRATION
Page 4
Hearing-Protector Test Fixture Type 45CA
Blind Plug
GR1079
Resilient base
Neck
Fig. 1.1 Assembled test fixture Type 45CA including Acoustic Plug and Acoustic Cup.
1 Introduction
The G.R.A.S. Hearing-Protector Test Fixture Type 45CA (Fig. 1.1) is for testing
•
Hearing protection devices such as ear muffs and earplugs
•
Sound sources such as headphones (supra-aural, circum-aural) and earphones.
The test fixture can be used with one of the following microphones or ear simulators:
•
1
"
or ½
"
pressure microphones. If used with 1
"
microphones, the test configuration conforms
with ISO 4869-3.
•
IEC 60711 (IEC 60318-4) Ear Simulator RA0045.
•
IEC 60318 (IEC 60318-1) Ear Simulator RA0039.
1.1
Main Features
The Test Fixture Type 45CA provides for reliable and exact measurements and was designed
with the following features:
• The test fixture, mounted on a resilient base (Fig. 1.1) that reduces the noise floor to a mini
-
mum in a typical test situation. Foam plugs and grease (Fig. 1.1) are supplied to avoid sound
leakage along the cable.
• The test fixture head, made for optimizing the acoustic isolation.
•
An acoustic cup and plug for testing the acoustic isolation (Fig. 1.1).
• A range of moulded-rubber KEMAR pinnae, e.g. for testing earplugs, can be fitted.
Head
Pedestal (neck + resilient base)
Two 1.5 mm Allen grub screws - must
ALWAYS be tightened when pedestal
and head are assembled
Cup
GR0974
Tube of
Sealing Grease
MI0016
2 x Foam Plug
GR1281
