On 9 Oct 2011, at 17:00, sursound-requ...@music.vt.edu wrote: > > Message: 7 > Date: Sun, 9 Oct 2011 09:39:36 +0000 > From: Fons Adriaensen <f...@linuxaudio.org> > Subject: Re: [Sursound] Soundfield-type mics: inverting or not? > To: sursound@music.vt.edu > Message-ID: <20111009093936.gb11...@linuxaudio.org> > Content-Type: text/plain; charset=us-ascii > > On Sun, Oct 09, 2011 at 10:16:22AM +0100, dave.mal...@york.ac.uk wrote: > >> Does anyone know, of the top of their heads, >> if a film set type clapper board reliably provides a positive going >> leading edge to it's impulse? I can't see it not, but I'd prefer that to >> be confirmed by repeatable experiments. > > I wouldn't rely in it. There's some air being squeezed out, but > that would be a low-F thing. The real 'clap' is the sound of two > pieces of wood hitting each other - I wouldn't make any guess > as to the polarity of that wavefront.
With larger clapper boards it is a bit of a mess, especially if you are a long way from the mic. Dog training clickers (search dog clicker on Amazon) work very well; you can get a pretty good idea of the frequency response too by an fft as the click is quite sharp and short. Drilling a hole in the back of it helps. The one I use produces a better click when you release the button than when you press. They are hopeless for dog training, our labrador regards it as a cue to grab the clicker from my hand and run off with it. Peter Fellgett used to burst a balloon (compressed air, not helium) at centre stage. This always produces positive pressure. Actually, with speech you can usually see polarity (we speak using positive pressure, usually), so just talking to the mic from centre stage is better than nothing. Geoffrey > > If you have a piece of bubble plastic around, making on of the > bubbles burst should produce a 'positive' pulse... > > Ciao, > > -- > FA > > > > ------------------------------ > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound > > > End of Sursound Digest, Vol 39, Issue 4 > *************************************** -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20111010/9435bc06/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
