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- Newsgroups: comp.sys.amiga.audio
- Path: sparky!uunet!usc!sol.ctr.columbia.edu!src.honeywell.com!hwcae!ericj
- From: ericj@hwcae.Honeywell.COM (Eric Jacobsen)
- Subject: Re: Halving sample speed while keeping pitch
- In-Reply-To: arensb@kong.gsfc.nasa.gov's message of 25 Aug 92 15: 51:55 GMT
- Message-ID: <ERICJ.92Aug25132514@lagos.cfsat.Honeywell.COM>
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- Nntp-Posting-Host: lagos.hwcae.az.honeywell.com
- Organization: Honeywell, Air Transport Division; Phoenix, AZ
- References: <9208241809.AA00474@.nairobi.inel.gov.inel.gov.>
- <ERICJ.92Aug24131911@lagos.cfsat.Honeywell.COM>
- <1992Aug25.155155.20785@kong.gsfc.nasa.gov>
- Date: Tue, 25 Aug 1992 19:25:14 GMT
- Lines: 44
-
- In article <1992Aug25.155155.20785@kong.gsfc.nasa.gov> arensb@kong.gsfc.nasa.gov (Andrew Arensburger - RMS) writes:
-
- >1. Upsample the signal until it is of the length you wish. The pitch
- >will be lower, but you can get the time duration you want.
-
- I believe the original poster wanted to avoid messing with the
- pitch at all.
-
- There's still some understandable confusion. The second step I posted
- was to mix the signal with a sine wave to bring the pitch back up to what
- it was originally.
-
- I did this thing once, by chopping the original signal into 50-
- sample segments. The segment size should be longer than the wavelength
- of the signal, but short enough to be almost unnoticeable. Then just play
- each segment twice, so that
- "hello world"
- becomes
- "hheelllloo wwoorrlldd"
- I didn't conduct an extensive study of appropriate segment lengths or
- sampling rates, but it seemed to me that slowing down human speech in this
- way worked fairly well (sounded like someone speaking verrrry slowwwly,
- albeit a bit choppy), but made musical instruments sound like hell.
-
- But if anybody does any kind of spectral-based speech recognition or
- processing they're going to be screwed with your method. FOr just
- listening it sounds like you have a novel method, but for detailed
- analysis you've added some bizarre harmonics, etc., due to the way you
- chop it.
-
- Depending on what the original requestor really needed you may have
- an interesting solution.
- --
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- * Eric Jacobsen Honeywell Inc. *
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