So, this video has been making the rounds today, and it’s just incredible, you need to watch it. In short, a very clever producer of music videos has cut a series of records to match the waveform of a dubstep song, and arranged them on a pole in time with the music.

I sent this video to my undergraduate phonetics class today, and one student emailed me back, asking “How accurate would that representation of the waveform be? What would it sound like if you played it back?”. Well, I have a conference call to prepare for, and I don’t want to be doing that right now, so I decided to go full nerd and do a bit of analysis instead and answer that question.

Let’s assume that the records were cut _extremely_ carefully, and that every record represents the amplitude at that moment perfectly. A stretch, but they seem to have done their homework. We’re also assuming (as seems to be the case) that the records are cut to a flat edge (rather than representing additional detail. Even with that assumption, does this represent the sound well? Let’s do the math.

The first record goes on at 27 seconds, the last at 1:52. That’s 85 seconds of audio. Those 85 seconds are represented by 960 vinyl records. This is a new record representing a slice of the waveform roughly every 0.088 seconds (the period). Using our frequency formula (f=1/0.066), that’s a record addition rate (sampling rate) of roughly 11 Hz. Bam.

So, we have a new amplitude sample 11 times per second. Now, we’re basically treating this as a digital audio file, which samples amplitude repeatedly at a given rate. The Nyquist theorem (which is awesome) states that the highest frequency captured accurately by a given sampling rate (the “Nyquist Frequency”) is 1/2 of the sampling rate.

For your average CD, your sampling rate is 44,100 Hz, which has a nyquist frequency of 22,050 Hz. This means that the highest frequency captured accurately in the recording is 22,050 Hz. Higher than humans can hear, but your pet dolphin isn’t impressed by your “Hi-Fi” stereo.

In this video, our sampling rate is only 11 Hz (11 records per second of audio). This means that the Nyquist frequency would be 5.5 Hz. Which means that if you were to “play back” the waveform here by pulsing the amplitude shown by the next record every 0.088 seconds, it’d be completely inaudible to humans (who can only hear 20Hz and above) as periodic sounds, and would just sound like a series of bursts of noise.

In effect, they’re representing a zoomed-out version of the waveform, which is incredibly awesome looking, but not a very good way to store audio information for playback. But that doesn’t take away from the fact that this is one of the more creative things done in a music video in a long time. So, I’d still chalk this one up as a victory for the producers of this video.

Alright, alright. I’ll go prepare for my conference call.

Tagged with Notes, Phonetics and Phonology, Reader Questions | Leave a Comment

03.22.12 | Crossing a line

So, last night, I’m dreaming quietly in bed. In my dream, I’m sitting in my Linguistics department’s phonetics lab (although it’s bigger and better equipped, it is a dream, after all). In comes a group of undergrads with an adult speaker of some unnamed language, and a faculty member from the department who does fieldwork and who I respect greatly.

They all sit down around a big table and start doing field research with the speaker, asking grammar questions, trying to pick apart the phonology (sound patterns) of the language. After a while, I get sucked in, and the faculty member baits me into joining, hinting towards what I was already thinking was a phonemic initial glottal stop contrast. (For the less linguisty among you, that means that in this dream language, the sound in “Hawai’i” or “Uh-oh” can occur at the start of the word or not, and whether it’s there or not changes the meaning of the word).

So, at this point being unable to resist, I jump in. I quickly start trying to elicit the speaker to highlight the contrast by having him repeat words, partly for my own joy and partly to show the undergrads what’s going on. Then, as is always wise in a field methods class, I start trying to produce those contrasting words myself, something I’m quite comfortable doing having spent as much time in phonetics as I have.

Then, in my dream, I realize that I couldn’t. No matter how hard I try, I just couldn’t make that initial glottal stop, I just kept producing the words without it. I knew it was there, I knew how to make it, and I knew it SHOULD be working, but I couldn’t do it. And worse still, the speaker was getting frustrated, the faculty member was judging me, and the undergrads were all starting to mock me. Finally, scared, confused, and completely glottal-stop-less, I woke up.

I think I have a problem.

Having dreams about linguistics is nothing new to me. Heck, I’ve even analyzed dream languages for hours while sleeping. But this one, to my mind, crosses a line. I’ve heard that police officers sometimes can’t fire their guns to save themselves in their dreams, and maybe firefighters sometimes run out of water in their dreams.

Now, I know for sure I’m in the right field because apparently for me, in a nightmare, it’s not that I’ll be naked in class, that my gun won’t fire, or that my car won’t start. Instead, I’m up at night worried about laryngeal misfires. If that doesn’t make me a phonetician and a linguist, I don’t know what would.

Tagged with Conventional Linguistics, Language Humor, Notes, Phonetic Phriends, Phonetics and Phonology, Tirades | 1 Comment


Just a quick note: My absolute favorite phonetics instruction software is sndpeek by Princeton Sound Lab, a real time Fast Fourier Transform and Waveform display program. Unfortunately, because Apple deprecated a bunch of old audio methods, it was broken with the update to Lion. However, some kind soul has updated the software to be Lion compatible, and it’s back to working like a charm. To download it, visit the sndpeek website and click on the “mac (mac osx lion) binary”.

To install, download the tgz file (the below code assumes you’ve downloaded it to the desktop), double click it to expand, then open a terminal and type:

cd ~/Desktop/sndpeek-1.3-exe

(then hit "enter")

sudo cp bin/sndpeek /bin/

Once you hit enter after typing the above command, OS X will then ask for your OS X administrator password (to copy the file deep into the filesystem), and once you’ve done that, at any point in the future, you’ll be able to just type “sndpeek” into a terminal and it’ll pop up a window displaying whatever sound source is selected in your Sound input preference pane. I usually give a more complex command to produce a prettier output, “sndpeek –logfactor:0.5 –lissajous:OFF –features:OFF –depth:150′”

I encourage you to play with the software as there are few better tools to help understand what a spectral slice is, how it works, and how spectrograms can be made. Enjoy!

Tagged with Computers and Software, Conventional Linguistics, Followups, Phonetics and Phonology | Leave a Comment

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