Subject: Re: acoustic shielding From: Densil Cabrera <densil(at)ARCH.USYD.EDU.AU> Date: Wed, 7 Jul 2004 22:16:51 +1000Satra, a couple of points: * the difficulty with sound insulation is blocking low frequencies - high frequencies are generally solved if you meet your low frequency criterion. * you might be able to estimate the characteristics of the desired material using the simplistic assumptions of the 'mass law' for sound insulation: the mass per square metre of material = 10^((attenuation+42)/20) / frequency. That equation assumes normal sound incidence (not random incidence, for which you probably need a bit more mass per square metre). It also has many other assumptions which may not apply, but it might be a good start for a flexible material. * one more hint - it is important to seal all air paths - the material must be airtight. densil >Hi Satra, > >you could try with small pieces of thick foam should do the >trick. this foam which is used for acoustic treatment: pads, >bass-traps and so one. not sure what it would give in only 8mm >though. > >Paul > >On Fri, Jul 02, 2004 at 01:01:55AM -0400, Satrajit Ghosh wrote: >> Dear List members, >> >> We are trying to increase the external attenuation of a set of headphones. >> Do you know of any non-metallic, non-magnetic, thin [less than 8mm], >> pliable material that can provide noise suppression upwards of 10dB upto >> 10KHz? >> >> Thanks, > > > > Satra > > > > -- > > Satrajit Ghosh > > Department of Cognitive and Neural Systems, Boston University > > -- Dr Densil Cabrera, Lecturer in Audio and Acoustics School of Architecture, Design Science and Planning Wilkinson Building G04 The University of Sydney, NSW 2006, Australia Telephone +61 2 9351 5267 Fax +61 2 9351 3031 densil(at)arch.usyd.edu.au