Subject: Re: Headphone sound pressure level? From: Dr JI Alcantara <jia10@xxxxxxxx> Date: Thu, 14 Jul 2011 04:18:54 +0100 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Hi Gemma, The sensitivity of the headphones is usually defined with respect to 0 dBV input (i.e., 1 volt RMS). So, 1 volt RMS should give you 113 dB SPL at (usually) 1 kHz. Note that depending on the frequency response of the headphones, you might get more or less at different frequencies with a 1V RMS input. If the headphones have a diffuse free-field frequency response, then they will probably be relatively flat from about 100 to 1000 Hz, with slight 'bumps' there on, and a steep fall off at 8-10 kHz. As far as the maximum output is concerned, this is a movable feast, depending on whether you want to know when the transducers are likely to burn out, or - more likely - when they start to produce appreciable amounts of distortion so that they become unusable for psychoacoustic tasks. The only way to be sure of the maximum usable output level is to measure their output at a variety of sinusoidal input frequencies of interest to you, and measure the total harmonic distortion. We usually do this using a B&K artificial ear and spectrum analyser, which you may have over there at IHR? Cheers, Jose On Jul 13 2011, Gemma Rachael Hutchinson wrote: >Dear all, > >We have a set of Sennheiser HD 280 pro headphones with a "sound >pressure level" of 102 dB "as per IEC 268-7". Since it also states a >sound pressure level of 113dB/1V rms, we are unsure exactly what the >maximum output level of these headphones actually is. The impedance is >64ohm. Would anyone know how to calculate this, or does anyone have >access to the full international standard for headphones (e.g., IEC >60268-7), a preview of which can be found at the link below? > >http://webstore.iec.ch/preview/info_iec60268-7%7Bed3.0%7Den.pdf > >Thanks, Gemma > -- José Ignacio Alcántara, PhD University Lecturer Department of Experimental Psychology University of Cambridge Downing Street Cambridge CB2 3EB UK Tel: +44 (0)1223 764412 Fellow of Fitzwilliam College Storeys Way Cambridge CB3 0DG UK Tel: +44 (0)1223 472126