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Re: Question on sound booths

Dear Leo,

What justified a big price difference between the two manufacturers?

Would you plan to use direct cochlear implant electrical stimulation, or acoustic free-field?

In case of EEG experiments, the big trouble would be that most of the electrical noise would come from the RF transmission and internal electrical stimulation.

In the case of direct stimulation behavioural tests or EEG experiments, it seems to me that the booth would make no difference!

I was wondering if the window size and cable-holes could have an effect on the frequency-range of the Faraday cage shielding (bigger windows/holes letting lower frequencies outside electrical noise in). Maybe window can be fitted with metallic nets linked to the ground to reduce that prob.


-----Original Message-----
From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Alain de Cheveigne'
Sent: 29 June 2010 13:44
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: [AUDITORY] Question on sound booths


In summary: (1) Define your needs.  (2) Identify issues specific to
your setting.  (3) Get the manufacturer to commit to measurable
specs. (4) Oversee the assembly.  (5) Don't pay until your
requirements are met.

Requirements may differ according to whether you'll be doing human
psychophysics, human electrophysiology, or animal physiology.  They
depend also on whether you'll be running near-threshold tasks or

If you'll be running tasks near threshold, threshold of hearing
defines the objective to attain.  If working with animals keep in
mind that they might have lower thresholds.  This determines your
requirements with respect to ventilation & light noise, and together
with external ambient noise levels, your isolation requirements.

Ambient noise is highly variable from setting to setting, and over
time.  Peak levels are usually what count (door slamming, loud
speech, etc.) rather than a long-term average.  Is the booth to be
installed in a room full of lively students?  Air conditioning is a
concern because the low frequency noise it produces is hard to
isolate against.  It may make sense to acoustically treat the room
that the booth is installed in (reducing reverberation reduces sound
level as well as voice levels).

Structure-borne vibration may be a issue (footsteps, machinery,
subway, etc.).  If so the booth may need to be installed on vibration

Sound absorbing inner walls and a carpet may be useful to limit
subject-produced noise.

Ventilation is a tricky issue.  You need ventilation during an
experiment, and in addition there may be official health
requirements.  Make sure that the manufacturer's specs apply with
ventilation on (and be prepared to fight on this issue).  Booth
ventilation inlets/outlets should not be connected to the building
air conditioning.

It's a good idea to have a window.  This allows to check if an
experiment is running (and the subject is still alive) and it allows
the option to install a screen outside to avoid acoustic and/or
electric noise.

Holes for cables.  These should be large enough for all the cables
you might need, including connectors unless you rewire them.
Plugging the space around the cables with putty should give adequate
isolation.  You can also install a box over the opening and fill with
acoustic foam.  Make sure that the tube that lines the hole does not
constitute an acoustic bridge.   A hole is more flexible than a patch

Fire alarm. Check the requirements.

Power outlet(s) inside the booth.  Power cables should be shielded.

Light.  Be aware that lights may produce sound, heat, and electrical

If you're doing electrophysiology (human or animal) it may be worth
having lights fed with filtered DC.   You may also want a faraday

It's a good idea to be present during assembly to check for obvious
mistakes such as damaged seals, acoustic bridges between walls,
missing calking, etc.

Define measurable requirements and make sure that you can force the
manufacturer to meet them.  For example make sure that they won't
charge you for testing.  Isolation is very hard to measure because it
requires extremely high sound levels outside the booth to reach a
measurable level inside.

Good luck!


>Dear List,
>We are considering two different sound booth manufacturers available
>in the California area. Both are offering the booths of comparable
>size and nominally same specs, but with very different prices
>attached to them. Does anyone have experience in ordering booths?
>How do we choose? Anything in particular to watch for besides the
>Thanks a lot!