Welcome to Audio Anecdotes

Three VolumesAudio Anecdotes is the title of a community contributed Audio Cookbook in the spirit of Andrew Glassner‘s classic Graphics Gems series.

Please read our article solicitation, and topics list, to get a better idea of what is coming and how you can help.

If you are interested in contributing articles (see author’s guide), have questions or suggestions please contact me, Ken Greenebaum!

Sound is such an important part of our lives, and should get more attention in the computer space (in user interfaces, games, data mining, etc.) This book fills a wonderful void in providing a lot of small, introductory articles, useful for anyone interested in computational sound.
Perry R. Cook, author of Real Sound Synthesis

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Entrainment (for the New Year)

I just saw Ikeguchi Lab’s awesome demonstration of 100 metronomes becoming synchronized via mutual entrainment (the metronomes are arrayed on a hanging platform to facilitate) and thought this was just the thing to share as we say farewell to 2016 and look forward to 2017. Let’s collectively make 2017 a healthy, happy, safe, and prosperous year!

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Had a good if commercial Maker Faire

I have a bit of an odd relationship with Maker Faire. I love the great people behind the Faire at Make Magazine/O’Reilly (and hope their recent troubles have been overcome), and the Makers themselves; am amazed by the tremendous community support as countless thousands attend Maker events, now around the world, with their children, the next generation of Maker, in tow. However I can’t help but be more than a little sad as the event has steadily retreated from the bastion of hard core independent geeks of the earliest event(s) to first become a little theatrical with burning man performance art and related trappings of steampunk and the like, followed by a shift toward children and education (but who can complain about that?), and most recently a huge shift from independent Makers presenting their research and project to corporations, and startups selling their brands or wares.

Over the years many fascinating Makers have either stopped returning or have dumbed down what they have brought. I am somewhat at fault myself having not hosted a booth for a second (third?) year after bringing one audio related interaction or another for the preceding three.

Complaints aside I did come away with a lot of new ideas, easily making the entry fee a great value even if I wasn’t able to see the entire show having spent half the day enjoying the Faire through my daugter’s fresh eyes.

Next postings will be about interesting  people, companies, products or discoveries from Maker Faire 2016.

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Maker Faire 2016

Regretfully I won’t be hosting a booth again this year at Bay Area Maker Faire 2016 but I will be attending and would to see and hear from you all. Let me know where you will be and what you are most excited about!

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Bluetooth over MIDI

The Moog Model 15 Modular Synthesizer app has me looking for a Bluetooth over MIDI solution (Apple incorporates native MIDI over Bluetooth LE support in iOS9: spec, tech note for app developers). I want to skip over the kludgey USB-MIDI-Camera Connection dongle stack to interface my old Roland keyboard to the iPad (replacing the ancient Yamaha CBX-T3 General MIDI Synth I have used forever).

Considering the mi.1 produced by quicco sound, a Japanese startup seems to be composed of old hands from Roland and Yamaha who introduced the mi.1 as their first product in a successful IndieGoGo campaign a while back. Like the size and self powered operation but am concerned about latency (the mi.1 FAQ states an additional 8.4ms latency over wired MIDI; not insignificant (see Derek DiFilippo‘s Audio Anecdotes Vol 1 article on perceptual audio latency) especially when added to the base wired MIDI latency, latency of the synth app, and latency of the app/coreAudio audio output.

From the original current loop interface, through MIDI over Ethernet, to now wireless MIDI over Bluetooth, MIDI is the standard that refuses to go away!

What are your experiences with MIDI over Bluetooth?

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Moogaliscious Moog Model 15 reborn as iPad App

A friend just forwarded me this YouTube demonstration of what looks to be an incredible new app from the developers of animoog; a polyphonic replica of the Moog Model 15 the classic 1970’s era analog Moog modular synthesizer designed for touring which has recently been put back into limited production for the not so modest sounding sum of $10,000.

While their animoog app was a fun introduction to analog synthesis the Model 15 synthesizer lovingly reproduces the actual instrument with every module, knob, and patch cable.

The app makes significant use of Apple’s Metal framework to render the user interface on the GPU freeing CPU for simulating analog audio. Apparently the developers are investigating using metal to accelerate the audio signal processing too.

Digitally simulating analog synthesis isn’t easy (naive digital implementations alias maddeningly and fail to produce the exquisite swept frequencies of the analog synthesizer). The developers mention use of over sampling which might get them part of the way there.  I would love to learn more!

In the mean time enjoy these Moog synth tracks, and for a simple introduction to Virtual Analog Synthesis checkout Phil Burk‘s article Bandlimited wavetable synthesis in Audio Anecdotes Volume 2.  For references to the current literature see Jussi Pekonen‘s Brief History of Virtual Analog Synthesis.

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Received my Doppler Labs Here T-Shirt

But I really want the device!

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Doppler Here. Where? Kickstarter…


A hearing aid for the rest of us?  No, don’t tell the FDA, but read on.

When I learned that Gints, an old SGI buddy and fellow signal processing advocate joined a small started called Doppler Labs I was curious so I visited their website and learned about Dubs their only product (earplugs with equalization provided via computer designed mechanical baffles tuned for listening to loud live music without damaging your hearing or the integrity of the experience).  Cool product, but how does that relate to Gints, an embedded DSP expert?

Recently I stumbled across Doppler’s Kickstarter campaign for their new product, confusingly called “Here”, and I began to understand Gints’ move. Here is an active, DSP based earplugs with impressive sounding capabilities that allow you to selectively tune in what you are listening to and tune out what you are no by providing:

  • a tunable equalizer providing 25 dB of attenuation and up to 5 dB of amplification
  • tunable active noise cancelation
  • effects!? (this band would be perfect with a little flange?)
  • all controlled in realtime via an iPhone companion app
  • in a pair of small, rechargeable, not too unhip looking packages

Frankly I am unsure what to make of Here, but am eager to give it a try and consequently ponied up the $199 Kickstarter funding level (the early bird specials had already flown)

Check Here out and let me know what you think…

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The loudest recorded sound?

The loudest sound recorded in the annals of history if not recorded on actual audio gear was apparently the 1883 Krakatoa volcanic eruption according to Aatish Bhatia’s fabulous article.

Some outtakes:

  • The sound was 172 dB SPL 100 miles away based on a barometer measuring the pulse at 2.5 inches of mercury
  • Sound waves (the compression and rarefaction of the atmosphere) top out at 194 dB SPL, in the Earth’s atmosphere, because at that SPL rarefaction leads to a vacuum, the limit of what is possible. Pressure waves above 194 db SPL simply push the molecules around and are considered shock waves.
  • The sound continued to reverberate around the globe (as measured by instruments) at roughly 34 hour intervals (the time required for sound to circumnavigate our planet.
  • The sound was observed by people up to 3000 miles from the island of Krakatoa

Aatish includes a link to a video recording of a relatively small eruption where the observation of the eruption was followed by a visible expanding shock wave with the over pressure eventually hitting the camera and the folk recording.

A list of high SPL sounds for comparison.

The story is not simply a curiosity but also a great tragedy as over 100,000 people may have perished in the eruption and resulting tsunami.

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See you at Maker Faire Sunday

mfheader477x109Yell if you want to connect with me at Bay Area Maker Faire this Sunday!

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Parallella Arrived!

Kudos to the Parallella team for shipping! I just received my Parallella and now need to find some time to power it up and find an interesting project. Soft Radio here I come?

Just to recap the parallella is a $99 board featuring the Epiphany 16 (or 64) Core ‘accelerator’, a Zynq-7000 Series Dual-core ARM A9 CPU/FPGA, 16GB RAM, Ethernet, HDMI, USB, running Linux…

Checkout the Adapteva Epiphany whitepaper

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