Re: [Phys-l] software needed

[Brian Whatcott <betwys1@sbcglobal.net>]

At 07:22 PM 8/19/2006, Josh Gates, you wrote:

> I'm looking for some free/cheap sound analysis software for class this
> year.  The only necessary requirements are:
> - record variable length samples from sound card
> - show waveform with time scale, pref. with autoscaling capability
> - FFT frequency spectrum generation
>
> That's it!  I find lots of stuff that's too expensive or has too many
> features and too complicated an interface to unleash on 9th graders - I'm
> really looking for a display something along the lines of LoggerPro from
> Vernier.
> thanks!
> jg

I was called on to help produce an APU startup whine for a panel trainer
recently.   The sound card in question had several modes, but playing
back a sound track wasn't an option - in the usual approach, each model
gets only a time slice at a given repetition interval, so I was forced into
using the FM method of synthesis. This represents 10+ year old sound
synthesis  technology popularized by Yamaha in a keyboard synthesizer,
 apparently.
The basis of the method is to generate pairs of tones which beat to
 produce   an envelope of sound. I downloaded a freeware bundle
which offers  scope,  spectrum and sonogram displays to help with
matching the synthesis to the sound track we recorded in the
APU operating position of the airplane.
These latter displays need  multiple passes of the waveform.
They filter the lead in and lead out in the usual ways in order
 to reduce artifacts. So the first step was to produce a potted
file of the sound to be analyzed: astep away from real time
display, of course.

I mention this to promote student exposure to sonograms, which
are used to study bird calls, speech development etc.
 I expect you will have seen the approach: time on the abscissa,
frequency as the ordinate, and sound amplitude indicated by
mark intensity (or color)




Brian Whatcott    Altus OK    Eureka!