Subject: Re: measuring output volume from headphones From: Frank Russo <russo@xxxxxxxx> Date: Wed, 6 Sep 2006 17:03:32 -0400You need a dummy head or a coupler to do this properly. The coupler sits between the headphones and a SLM (like the one you are using from Radio Shack). Professional couplers are generally available for super-aural headphones such as those used in audiometry (good option but expensive for a single use). Here are some other options to consider: You can try using a "semi-professional" coupler that can be set up for use with various types of headphones -- e.g., http://www.digital-recordings.com/coupler/coupler.html (inexpensive option that may be acceptable for situations where precision is not critical) You can try building a coupler yourself by fitting the base of a cone-shaped cylinder (e.g., a strofoam coffee cup) with a rubber seal (bad option that should only be used for rough equalization -- not for absolute measurements!) You can equate the two systems perceptually. Have a small subset of listeners scale loudness for a few levels of output on each machine. Adjust sound output level on each respective machine so that sound output at test is of equal loudness (good option but this won't provide you with dB SPL levels that can later be reported) Finally, you can find someone local that has a dummy head (complete with pinnae and ear canal embedded microphones) and ask to borrow it for a day (best option). ------------------------------------------------------------------------ - Frank A. Russo, Ph. D. Assistant Professor Department of Psychology Ryerson University 350 Victoria Street Toronto, ON M5B 2K3 Canada Email: russo@xxxxxxxx Web: http://www.psych.ryerson.ca/russo Tel: 416-979-5000 ext. 2647 Fax: 416-979-5273 -----Original Message----- From: AUDITORY Research in Auditory Perception [mailto:AUDITORY@xxxxxxxx On Behalf Of Robbin Miranda Sent: Wednesday, September 06, 2006 3:11 PM To: AUDITORY@xxxxxxxx Subject: measuring output volume from headphones Hello, Can any of you recommend a way to measure the output volume/decibel level from headphones? We will be testing participants using auditory music and speech stimuli on two different computers (depending on availability of the two testing rooms) and would like to make sure that the output volume level is equivalent at both locations. We do have a decibel meter (from Radio Shack), but this doesn't seem feasible to use with headphones. Thanks, Robbin Robbin Miranda Interdisciplinary Program in Neuroscience Georgetown University 3900 Reservoir Rd., NW Washington DC 20007 (202) 687-8449