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Re: Headphone sound pressure level?
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