Math 5: Aural postings

Please post real-world examples of mathematical, musical, or sonic phenomena we discuss in class, either in the form of discussion, articles, links, spectrograms, pictures, or best of all sound files (either from recordings, found, or produced by yourself). If you post a sound file, please describe what it is, why we should care, what phenomena it relates to. You do not have to post every single week, but should aim for 5-7 interesting posts in total. The more you do (and more thoughtful and interesting!), the more credit. We will discuss them at the start of each Monday lecture. Happy aural hunting!

Enter your post in the window below. You must provide your name (note: "Your name" doesn't mean a description of the posting, rather your actual name). If you don't provide your name and submit the comment, the comment will disappear from the text field and you will have to type it again. To avoid frustration I suggest you compose your comment on a text editor then paste in when you're ready. Scroll down to read previous posts.

For uploading sound files there is a 2MB limit, ie about 2 minutes of MP3 or OGG format, but only 12 seconds of WAV. Therefore I recommend you use MP3 or OGG (convert using audacity). In all cases keep them short! Your uploaded files will remain on the Math Dept server. Unfortunately you cannot remove a comment or file yourself; email me if you must have something removed. We all take it for granted you won't post dumb/offensive material.

You may embed HTML in your post such as <BR>, <P>,
<B>...</B>, etc for formatting purposes. I encourage you to include links like this: <a href="http://interesting.site.org/">check it out!</a>
You may also cut from a document and paste into the comments area.

Your name:
Upload: (file size limit is 20MB)
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Uploads are only allowed from Dartmouth wired network, Dartmouth Secure Wi-Fi or VPN.

Name: Maggie Flanagan
Date: September 27, 2011 (15:52)
File uploaded:
Comment: http://www.freesound.org/ This is a link to an online sound repository. I have used many of these sounds for digital compositions in the past, and there is some really cool (and weird) stuff on there. The process for accessing the files is simple: make a free account. Have fun!

Name: Evan Griffith
Date: September 24, 2011 (16:00)
File uploaded: Upload1.zip
Comment: The attached ZIP file contains two items, an mp3 clip and a photo capture of the sound wave from the file. In the file, I play a very low C on my keyboard (2 octaves below C1) and then I play a C4 ("middle c") right after. Notice the changes in the wave as I switch from the lower C to the higher C. The sound I am using is the "Sawtooth synth." Similar to the Frac waves we studied in class, you can see the tooth-like structure of the wave's periods. Due to the higher frequency of the higher c, there are more repetitions per second and so the pattern is less distinguishable than that of the lower C without zooming in.

Name: Alex
Date: November 15, 2010 (19:09)
File uploaded: Roundabout Intro (reversed).ogg
Comment: Here's the same intro bit (the swell) played in reverse. Turns out it's just a big piano chord played backwards, so that the decay sounds like a crescendo. You should check out the rest of the song, too! It's a good one.

Name: Alex
Date: November 15, 2010 (19:06)
File uploaded: 04 Roundabout.ogg
Comment: This is the opening to a classic rock song, "Roundabout" by Yes. This makes the effect of attack on timbre very obvious. First check out this bit (the original song).

Name: Project Topic
Date: November 12, 2010 (16:07)
File uploaded: Erik Satie - Gymnopedie No.1.mp3
Comment: Although this is going somewhat backward in the course, I found myself drawn to Erik Satie's piano piece "Gymnopedie No.1" because of its usage of simple pitches and intervals. In my project, I hope to look into just what techniques Satie used for combining these various tones in the piece. Also, since Satie's piece was somewhat unprecedented when it was published in 1888, I want to look into the influence it's had on other musicians since. For now though, just enjoy the piece itself.

Name: Bailey Hoar
Date: November 11, 2010 (22:42)
File uploaded:
Comment: Because we've been talking about the human voice, I thought I'd share a link to Arvo Part's "Magnificat" (which the Glee Club is singing on Sunday--shameless plug). It has a lot of close harmonies which require the singers to be forming their vowels (and therefore their formants) in exactly the same way in order for the piece to sound good: http://www.youtube.com/watch?v=kVlGIrXGepc

Name: Final Project Topic
Date: November 11, 2010 (22:40)
File uploaded:
Comment: Grace and I are going to examine how formants vary among female singers of various ages, voice parts, and styles. We'll start by recording the same series of notes (varying in vowel, pitch, etc) for each of our subjects, and then move on to analyze the formants they produce. We're hoping to find out whether vocal range (soprano vs. alto), age (younger, our age, older), and training/singing type (whether a singer is classically trained, usually sings musical theater, has no training, only sings a capella, etc) have any effect on formants--and if so, what effects they have.

Name: Alarm Clock
Date: November 02, 2010 (17:07)
File uploaded: alarm-clock.mp3
Comment: My alarm clock beep. Fundamental is 2095 Hz by my measure, which is almost exactly C7 (2093 Hz). The first 7 partials are present (roughly): 2095, 4121, 6099, 8173, 10198, 12288, and 14346 Hz.

Name: Afra Zomorodian
Date: November 02, 2010 (11:52)
File uploaded: riedel-red.mp3
Comment: Riedel red wine glass, hit with a spoon. Strong partials at 597, 1538, and 2877 Hz. Weaker partials at 2095 and 3072 Hz, the last of which is within dissonance range (Helmholtz theory.) There is a beating at 10Hz. Tau is much higher than the spirits glass (0.97 for spirits, 2.11 for this glass), but Q = 3956 is about the same as the frequency is about half.

Name: Riedel Glass (Spirits)
Date: November 02, 2010 (10:38)
File uploaded: riedel-spirits.mp3
Comment: Glass hit by a metal spoon. Strong partials at 1294 Hz and 3279 Hz. A weaker partial at 5995 Hz. Quality factor = 3954

Name: Maryam
Date: October 27, 2010 (12:29)
File uploaded: cymbalcrash2.wav
Comment: This is the sound of a cymbal being hit by a drum stick. The sound has partials at 160, 262, 435 Hz. The sound clearly decays but because the amplitude increases before decreasing with a cymbal, the measurement for decay seems harder to calculate.

Name: Sophia Golvach
Date: October 27, 2010 (09:51)
File uploaded: snare.wav
Comment: We have a drum set in Panarchy. Here is a snare drum sample. 534 Hz is the strongest partial, other strong partials including 120 and 240. These two are clearly related. However, the strongest is 534 Hz. Perhaps 60 is the highest related partials.

Name: Grace Lempres
Date: October 27, 2010 (01:49)
File uploaded: stove hood.wav
Comment: I made this noise by hitting the hood over our stove with a metal fork. I think it demonstrates several complex vibration modes (I hope!). There were strong partials at 192 Hz, 338 Hz, 608 Hz, 879 Hx, and 2710 Hz (which do not all fall into an even pattern). I used praat's linear intensity line in order to determine that the decay time for the noise was only .0038 seconds -- the sound definitely dies off quickly!

Name: Alex Barnett
Date: October 20, 2010 (11:43)
File uploaded: Mayan_pyramid_clap_chirp_echo.wav
Comment: Here is the clap and echo recorded at a Mayan pyramid in Mexico; the chirp is actually downwards (what does this tell you about the shape of the staircase?) The 1998 article by Lubman is here. Since then it has done the rounds of the science news media, such as Nature

Name: Alex Barnett
Date: October 06, 2010 (12:07)
File uploaded: Mears_1850_hibberts_pitchshifted.wav
Comment: Here's a better bell analysis example than in lecture. It's a Mears bell from 1850, downloaded from here. The partials are: 329, 531, 708, 1161, 1724, 2348. Taking ratios you'll find the last three form multiples of 580 (multiples: 2.000, 2.972, 4.048), so that is the perceived pitch, which is close to D5.

Name: Jeff Hopkins
Date: September 29, 2010 (04:02)
File uploaded: 15 Stardust 1.m4a
Comment: Dave Brubeck's rendition of the jazz standard "Stardust" opens with a long series of pure tones. Looking at just the first 5 seconds (the series goes on for about another 20 seconds more) with audacity, Brubeck starts off with A5 then moves to F4, F5,A5, and finally D#4. The rest of the song's also pretty awesome, so I'd encourage a listen

Name: Grace Lempres
Date: September 29, 2010 (02:06)
File uploaded: faure requiem agnus dei.ogg
Comment: Sorry for the bad sound quality! I couldn't figure out how better to get a clip of this recording of the piece into audacity... We were working on this piece in Chamber Singers today trying to get the exposed soprano entrance (starts around second 11.5) as pure as is possible by voice. We've been looking at instrumental examples of pitch and, as a singer myself, I was curious to see how close to that purity of pitch voices could get. The Tanglewood Festival Chorus obviously did a great job with this work -- audacity found the most prevalent frequency to be at 524 Hz or C5, just on pitch with what Faure intended.

Name: maryam arain
Date: September 29, 2010 (00:26)
File uploaded: 14 Goldberg variations - Aria 1.mp3
Comment: goldberg variations, a bach aria, opens with G5, at a measured frequency of 790 Hz according to audacity.

Name: Sophia Golvach
Date: September 29, 2010 (00:00)
File uploaded: 000022Ludwig van Beethoven - Symphony No. 7 in A major, Op. 92, II. Allegretto.mp3
Comment: Whoops! Sorry. I am uploading this entire file because I am not sure how to cut it with Audacity. The first chords are A minor chords. The note "A" with a frequency of 440 Hz is the base note of Western classical music, which is why I chose this symphony. The first movement is Major, but I prefer the second movement, which bases its first chords on A3, an octave down A4. Thanks!

Name: Beethoven's 7th Century II. Allegretto
Date: September 28, 2010 (23:56)
File uploaded: Ludwig van Beethoven - Symphony No. 7 in A major, Op. 92, II. Allegretto.mp3
Comment: The first note is A, which is the standard of Western Classical Music. Unlike the first movement, the allegretto is in A minor, yet it still opens in A.

Name: alex barnett via afra zomorodian
Date: September 24, 2010 (12:03)
File uploaded:
Comment: The Mosquito - `controlling' teenagers via high-frequency sound Here's the old news from 05: http://news.bbc.co.uk/2/hi/uk_news/wales/south_east/4415318.stm http://news.bbc.co.uk/2/hi/uk_news/7240180.stm Teenage use of the same pitches: http://www.npr.org/templates/story/story.php?storyId=5434687 Wiki on the alarm: http://en.wikipedia.org/wiki/The_Mosquito Recent description by inventor: http://www.npr.org/templates/story/story.php?storyId=129581152

Name: alex barnett
Date: September 16, 2010 (17:44)
File uploaded: ACDC-Bells.mp3
Comment: The attached is the sound of the Denison bell, manufactured in 1923, in Leicestershire, UK. It was used as the opening of AC/DC's Hell's Bells. Is the signal periodic? Zoom into the waveform using audacity or praat and you'll see it's not. However, it does contain strong partials, the lowest being at 82 Hz. More about that later!

Name: alex
Date: September 16, 2010 (17:42)
File uploaded:
Comment: test