Syd,
I ahve the address for Oreilly's web site. A lovely group of people and a
wonderful video!
http://www.oreillys.com.au/content/default.asp
Thank you Syd for bringing these folks to my attention, also the little island
(the name escapes me right now) you mentioned at length in another message to
the group.
J.
[Non-text portions of this message have been removed]
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>From Tue Mar 8 18:27:11 2005
Message: 13
Date: Fri, 14 May 2004 16:53:32 +1000
From: Vicki Powys <>
Subject: Re: Sample Rate Conversion
Walt wrote:
> On the basis of your statements that you believe yourself to have very
> good high frequency hearing, I would think you probably are judging
> these samples on the basis of the high frequency band. If you have a cut
> filter available, try filtering out everything above 10khz or so and
> listen to the lower stuff. That was something else I did with these
> samples was to cut out various bands so as to listen to just each part.
Well I've tried it the other way around, just to see what I am basing my
judgement on, in comparing these insect sounds. And yes I am definitely
judging the insect sounds from the high frequency band. I've just tried
using the Telephone Filter (i.e. brick wall filter) in Waves Q10 plug-in in
Peak LE. I've used this as a low-cut filter just to see how high I can hear
this insect sound. I can run the low cut filter right off the dial at the
high end without adjusting the volume, and there is still some audible sound
right up in the 20 kHz end. It is hard to tell just what the reading really
is, but this is how I'm measuring it: In Q10 I have buttons 1-2-3-4-5 all
ON and 6-7-8-9-10 all OFF. I am adjusting the frequency by shift-clicking
1-2-3-4-5 in the frequency column, to drag the low cut further to the right.
Taking my reading from 2-3-4 (which are all the same), I am hearing a clear
sound and the same loudness up to 14 kHz. At 14 kHz the loudness is very
slightly less, then tapers off as I go upwards but I can still just hear
some sound when 2-3-4 read 20 kHz. (1 & 5 have a different reading to
this.)
I had a look at the various insect files in Audiograph and you are quite
right, there is a very faint band of sound between 4.5 & 5 kHz. The main
band shows very clearly at 10-16 kHz.
I tried converting the 48k file first to 65k then to 44k (in Peak LE) but it
sounded identical to a file converted direct to 44k. In 'Save As' I only
have the option of 16 bit or 8 bit, so that wasn't any help.
If nothing else, this exercise is a good way of learning more about using
sound software! Thanks for your tips Walt.
Vicki Powys
Australia
on 12/5/04 12:16 PM, Walter Knapp at wrote:
> From: Vicki Powys <>
>
>
>> Walt and all,
>>
>> I checked out the Sound Out possibilities. On my iMac running OS9, in Peak
>> LE, I can choose ASIO or Built In. Built In seems better than ASIO and is
>> the default. With Lang's insect sounds, Built In (listening via Peak) and
>> Quicktime (used separate from Peak) were identical in listening results.
>
> OS9, and the Peak that runs in it are virtually entirely different than
> OSX and the Peak that runs in it. They appear the same, but all the
> underlying programming is quite different. ASIO appears to have gone
> away in OSX to be replaced by Core Audio and two versions of HAL (and
> others depending on your hardware). There is still a built in option, in
> the system sound options, and it could be using Core Audio/HAL or
> whatever. Much more complex.
>
>> I cannot try Walt's Magic trick as Peak LE does not support sample rates
>> above 65 kHz and I don't think I can change the bit rate either.
>
> The particular rate I gave was the highest rate my OSX G4 running a OSX
> native Peak will allow. I did try the various steps below that one, and
> the higher I went the better the results. Even the 64 you can do helps a
> bit.
>
> Peak won't change the bit rate within a open file. You have to do a save
> as... and set a new bit rate in the options for the aiff file. Then open
> that new file. I'm not sure how much of all that is built into Peak LE,
> been a very long time since I used it.
>
>> The sample files at 14 secs and 1.2 MB are too large for me to download any
>> more. 5 second samples would be plenty.
>
> I know all about that, my connection is barely faster than yours.
> Particularly at uploading the files to the server. And they are eating a
> bunch of server space, so will not be up all that long.
>
>> My assessment of the sounds is same as before, and Walt's magic files
>> sounded poor, compared with the original 48kHz. Interesting that none of us
>> agree on this!
>
> There are three people here, all have listened to the samples, and we
> have three opinions right here. Though not far apart.
>
> With the variations in equipment, the variations in our ears and so on,
> it's a wonder if we all hear the same thing in anything.
>
> My threshold of hearing at frequencies from 10khz to 20khz is nearly
> even, and at about 40-60dB louder than my threshold of hearing at 1khz.
> I can hear these samples, but have to turn the gain on the headphone amp
> up a lot. At that gain the errors in some samples in the lower
> frequencies become very audible even though they are a lot quieter. I
> can even hear Rich Peet's Bat, with lots of gain cranked in. My son, in
> comparison does not have to crank in much extra gain to hear the high
> frequencies in the sample. To make it even more fun for me, my left ear
> is less sensitive than my right, something I think is due to all the
> driving I've done in my lifetime with the window down.
>
> In these samples we have a wide high frequency band that is by sonogram
> the loudest thing in the recording. We also have a much fainter narrow
> band at 5khz and at about the same level sound below 160hz. In the
> original Peak and Soundhack samples sonograms show additional noise
> introduced between about 2khz & 5khz, a conversion error. This extra
> noise is at about the same level as the other faint parts.
>
> Now think about two simplified types of hearing. One like mine will hear
> the high band as the same volume as the low band only if it's 40-60dB
> louder. It is nearly that much louder, but not quite. So, when I amplify
> the high band to hear it, the low frequencies also get amplified up into
> my audible range at nearly the same time. I hear all the various
> frequencies at similar apparent volumes. Now think about a person who
> has little high frequency loss, my son, no extra amplification is needed
> for the high frequencies and he is fairly evenly sensitive to all
> frequencies. Since the high frequency is so much louder than the others
> my son will hear it before the lower stuff reaches his threshold of
> hearing as he turns the gain up. The high frequency band will definitely
> dominate the sound picture, or even be all heard. He will judge the
> quality of the samples mostly on the high frequency band, hardly hearing
> the others. And since most of the differences Lang and I hear are in the
> lower stuff, may come to different conclusions.
>
> On the basis of your statements that you believe yourself to have very
> good high frequency hearing, I would think you probably are judging
> these samples on the basis of the high frequency band. If you have a cut
> filter available, try filtering out everything above 10khz or so and
> listen to the lower stuff. That was something else I did with these
> samples was to cut out various bands so as to listen to just each part.
>
> That all, of course, leads into a discussion on the perils of
> equalization, but that's a separate subject.
>
> Walt
>
________________________________________________________________________
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"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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