Home ] Up ] Contents ] Feedback ] Website News ] Search ] Technical Tips ] Web Resources ] OSHA Issues ] MEPCOM ] Noise Resources ] Presentations Archive ] About ] Top Page 4 ] About ]

                                              Selecting A Room 

 Lipin/Dietz Associates, Inc.

Audiometer Calibration
Audiometer Power Protection
Audiometer Calibration Services
Audiometer Paper & Supplies
Audiometer Parts & Supplies
EarShield™ Earphone Covers
Electroacoustic Ears
Municipal Noise
Occupational Health Services
Occupational Health Software
Occupational Health Software
OHM® Software Services
Otoacoustic Emissions
Parts & Accessories
Quest Noise Dosimeters
Quest Sound Level Meters
School Health Instruments
Sound Level Meters
Spirometer Data Switch
Vision Testers
T2 Vision Testers


Selecting an Audiometric Room
By ALAN ECKEL, President, Eckel Industries Cambridge, Mass.
The basic purpose of a sound room in audiometric testing is to provide the proper acoustical environment so that tests can be conducted without interference from outside noise. A room of this type should afford adequate ventilation and lighting so that the subject will be comfortable while his hearing is being evaluated. Not only does the room supply environmental control but it eliminates distraction from changes on the visual horizon which may invalidate an audiogram as readily as acoustical interference.

Hearing test rooms should be located in as quiet a place as possible. Preferably they should be within practical access but away from outside walls, elevators, heating and plumbing noises, waiting rooms and busy hallways. If the highest noise levels in a test room do not exceed the levels listing in Table 1, tests room noises will not affect test results.

To obtain these internal room ambients one must know what the outside ambient is going to be. This can be obtained with a noise survey by octave bands of the area where the room is to be located. Once this is done, a room should be selected which will provide ample noise reduction to bring the internal noise down to those prescribed by the standard (Table 1).

Background Noise Levels

The American Standards Assn., in its pamphlet on criteria for background noise levels in audiometer rooms, has printed a very useful chart for depicting the outside background noise levels allowable for the use of different types of sound rooms, i.e., regular duty single wall rooms and double walled rooms. This chart shows the relationship between outside ambient levels and the amount of performance required to bring down the internal noise levels to the acceptable levels for testing without interference.

The following procedure gives a rough indication of the kind of construction that may be necessary. In the octave bands that will contain test tones, measure the sound pressure level at the site of proposed test room and plot those on Figure 1. The highest range in which the measured levels fall determines which of the three general classes of rooms is probably necessary.

Specifically the octave band background noise at the room location should be measured at teach test tone; 125, 250, 500, 1000, 2000, and 4000 Hz. From these measured levels the published noise reduction of the proposed audiometric room should be subtracted. To be acceptable the room must bring the noise down below that prescribed in the standard listed in the table below that prescribed in the standard listed in the table.

* Test Tone of 6000 Hz is also required.

Types of  Rooms

Basically there are three types of prefabricated audiometric rooms. The first type, which is most familiar to those in audiometric testing, is the single wall modular panel type. It is fabricated from a 4" (100mm) thick, steel panel, which weighs approximately 10 lbs. per sq. ft. This panel has a solid outer surface and a perforated inner surface and is filled with high density acoustical fill and damping material.

These panels require assembly at the location where they are to be used. The components of such rooms include sound doors, window panels and a panel with a jack plate for connection of the audiometer. Separate floor and ceiling panels are necessary.

The second type of room is a hybrid heavy duty version of the first. It incorporates double wall panel construction. These are rooms within rooms and are usually constructed using the same 4" panels with a 4" air space between the inner and outer rooms. Both of these types of modular panel rooms can be assembled to construct a suite of rooms with capacity for many subjects.

The third type of room is a unique development in the field of audiometric testing: compact or mini-room. It is a smaller, single walled, one person occupancy unit which incorporates the features of the larger room in a smaller pre-assembled package, Figure 1. It provides somewhat less noise reduction than the larger rooms but is more that adequate in most industrial testing applications.

All three types of rooms should include adequate lighting, (incandescent or fluorescent with remote ballasts to avoid ballast hum), adequate ventilation (15 air changes per hr.) which does not distribute background noise levels, as well as vibration isolation mounts to isolate from structural vibration.

For precise medical and clinical applications, where extremely low ambients are required and radio frequency shielding may be a requirement for diagnostic work, the single-wall and double-wall modular panel rooms are most practical in this type of application and in speech and hearing research.

In industrial testing and some clinical testing, the single-wall modular panel and smaller pre-assembled compact rooms will be adequate depending on the background noise. They afford sufficient noise reduction to satisfy these testing requirements.



Home ] Up ] Audio Booth Noise Reduction ]

Copyright © 2012 Lipin/Dietz Associates, Inc.


All material contained herein, unless otherwise noted or linked to entities other than this one, remain property of Lipin/Dietz Associates, Inc. and reproduction of them in any form, without exclusive permission, is a violation of applicable copyright laws. Copyright © 2008 Lipin/Dietz Associates, Inc.
All Rights Reserved

Last modified: October 28, 2015