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Having some experience with buying booths... All other things BEING EQUAL, price differences are due to: Shipping and handling charges. Where are the two booths originating from? Manufacturer of the booth - each manufacturer has different prices The middle man - booths usually do not come from the manufacturer; they come from a "dealer." Dealers tack on surcharges. Set-up and Installation fees - make sure this is included. Taxes hbj ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Harriet B. Jacobster, Au.D., CCC-A, FAAA Board Certified in Audiology hjacobster@xxxxxxx Idrick Akhoun wrote: 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. Cheers, Idrick -----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 Leonid, 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 suprathreshold. 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 isolators. 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 panel. 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 interference. If you're doing electrophysiology (human or animal) it may be worth having lights fed with filtered DC. You may also want a faraday cage. 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! Alain |