Yes keys do have ultrasonics too. It is such a complex signal that it
leads to an easy ear check of a recording system.
Too complex and long to give a good paper trail. The key compared to
the spark have some things in common but on the amptitude display I
also see strong different harmonics that I don't see on the spark.
My car keys recorded at 3 inches. The spark was recorded at 1 foot.
In the linked photo I have the key jingle first and then I have
appended three separate spark sounds. Same mic, same recorder, etc.
http://home.comcast.net/~richpeet/keyspark.jpg
For measurement of attenuation of different frequencies for my wind
blimp I think I am better off with the spark. But am open to
suggestions as I just hack at this.
Rich Peet
Rich Peet
--- In Lou Judson <> wrote:
>
> Have you tried a key jangling test the same way? I'd be curious to see
> a similar image from that, the traditional test used for mic pre
> distortion - care to do a comparison? Certinly safer than the spark, is
> it as effective?
>
> How close was the spark to the mics?
>
> <L>
>
> Lou Judson =95 Intuitive Audio
> 415-883-2689
>
> On Mar 23, 2007, at 11:32 AM, Rich Peet wrote:
>
> > How high will a standard mic go.
> >
> > Someone else with more experience than me would have to comment on
> > what the freq response curve of a gas grill bbq piezo starter is but
> > it seems to go into RF frequencies.
> >
> > Testing two standard mics with the bbq starter I noted that on
> > multiple sparks that the spectrum display looks identical each time.
> > Then changing mics I get a different pattern that once again does not
> > change from spark to spark. So I conclude that an electrical spark is
> > a way to check the freq capability of your equipment. I have no idea
> > if this method could be dangerous to electronic devices and would not
> > be surprised if there is a risk.
>
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