This test is very useful for us, maybe also can be useful for you. 

With this product we tried to make a portable, personal and multipurpose audio test signal based on shaped tone bursts. The idea came from LinkwitzLab , a Siegfried Linkwitz site. Some of the possible usages of shaped tone bursts are described in detail on his site for testing loudspeakers and room acoustics.

 

Publications about basic test principles can be found at the Audio Engineering Society site:

 1. "Shaped Tone-Burst Testing" JAES Volume 28 November 4pp. 250-258; April 1980. Author: S.Linkwitz

2. "Narrow Band Impulse Testing of Acoustical Systems" 60th AES Convention, Los Angeles 1978, Preprint 1342. Published as Ref. 13. Author: S.Linkwitz

Some online information can be found in Siegfried Linkwitz interview, published in Stereophile magazine, written by Shannon Dickson, April, 1996.

You can find more informations about possible usage and test principles in references .

 Fig1. Base signal, 4 periods of sine function modulated with Hanning window

 Fig2. Frequency response

 Fig3. Test signal timing in wav file

 

 

 

 

Features:

 

 

• 16bit word-length, and 48kHz sample rate, two channels, and pure uncompressed PCM wave data
• Raised cosine window (Hann ) with four sine periods in it, this singal is also known as shaped tone burst
• Not  tiring ... it's nice sounding
• It's like movie, with frequency values titled on the screen, and easily readable from some distance
• Cover frequency region from 10Hz to 24kHz
• Long pauses between signals. You have time for "processing" in your brain
• Absolutely synthetic, with extended spectral purity
• Double precision was used for calculations
• Signal isn't dithered; it's quantized only
• Built from ground-up written C code, directly to hard disk, and is never been transferred through any audio interface
• Large number (426) of possible frequencies for large number of applications
• We split it to three main files, low, mid and high frequencies:

• 10Hz-100Hz - 91 frequencies
• 100Hz-1kHz - 290 frequencies
• 1kHz-24kHz - 47 frequencies.

• Totally 426 frequencies

• It's very portable. When archived with some archiver program, because pure zeroes in silence periods, file can be very small... compression is near 1:100
• It's free

 

 

 

 

Applications

 

BoZo audio test (shaped tone bursts based ) can be used to precisely pin-point-by-your-ears the problems:

• Acoustical auditory tests of speakers and recording spaces
• Driver deviations and detection of malfunction in speaker voice coils and spiders
• Can discover cavity resonances and parasite Helmholz resonators caused by bad driver/cabinet design, or defects
• Detection of back-reflections in all box-type loudspeakers
• Detection of late impulses in ported-type loudspeakers (bass reflex and transmission line type)
• Can discover structural resonances
  

 

 

 

 

Recipe for Making BoZo Audio Test:

 

 

1. Study wav programming howto
2. Learn how to write 24-bit data sample in wav file
3. Study Hann window theory
4. Write C code which will generate wav file
5. Compile code
6. Test generated wav
7. Change C code
8. Go to 5

 

 

 

 

REFERENCES

 

 

• "Narrow Band Impulse Testing of Acoustical Systems" 60th AES Convention, Los Angeles 1978, Preprint 1342. Published as Ref. 13. Author: S.Linkwitz
•  "Shaped Tone-Burst Testing" JAES Volume 28 November 4pp. 250-258; April 1980. Author: S.Linkwitz
• Siegfried Linkwitz interview , published in Stereophile magazine , written by Shannon Dickson, April, 1996.
• "Development of Test Signals for the EIA-426-B Loudspeaker Power Rating Compact Disk" 111th AES Convention, New York 2001, Author: D. B. (Don) Keele, Jr.

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