Elmer Cat

Research Scientists

Postdoctoral Scholars


Benjamin Balas

Kimo Johnson

Aude Oliva


Recent Alumni

Shayian Keshvari

Jianhua Li

Benjamin Wolfe

Siyuan Dong

Shaoxiong Wang

Dian Yu

Wenzhen Yuan

Zhendong Zhang

Bei Xiao

Krista Ehinger

Xuetao Zhang

Derya Akkayanak

Phillip Isola

Rui Li

All Alumni

The Perceptual Science Group of the Department of Brain and Cognitive Sciences at MIT does research in human vision, machine vision, human-computer interaction, and touch sensing for robotics. Both the Adelson Lab and the Rosenholtz Lab are part of the Computer Science and Artificial Intelligence Lab (CSAIL), located in the Stata Center.


  • TextEdit via Terminal

    open -a TextEdit  [filename]

  • Show Hidden Files with Finder

    defaults write com.apple.finder AppleShowAllFiles TRUE
    killall Finder

  • Mister Rogers Remixed – Garden of Your Mind

  • Kitty Carlisle – Sweep Tone Ring

    The charming and talented Kitty Carlisle sings vintage telephone sweep test tones in this slightly alarming and somewhat annoying ringtone.

    ➤   Download for iPhone in “m4r” format

  • Kitty Carlisle – Panel Pulsing Ring

    (to replay, click the X)

    The charming and talented Kitty Carlisle sings the “No Such Number” vacant level intercept tone from a #1-Step central office in Montreal Quebec in this raucous ringtone which also features vintage telephone sounds from the famous GEdney-9 electromechanical “Panel” central office.

    ➤ Download this ringtone

  • GEdney-9 Panel Pulsing Ring

    (to replay, click the X)

    This lively mashup ringtone combines ringback tone from the famous GEdney-9 panel exchange with the sounds of electromechanical revertive pulsing. Towards the end of the ringtone, a GEdney-9 busy signal joins in, alerting you that time left to answer your call is running out!

    ➤ Download this ringtone

  • GEdney-9 Didja Dial Ring

    A medley of quaint Intercept Operator sayings.

    ➤   Download for iPhone in “m4r” format

    ⬅  Back to Ringtone archive

  • GEdney-9 Panel City Ring

    (to replay, click the X)

    This is a simple “City Ring” ringback tone from the famous GEdney-9 Panel exchange, located in New York Telephone’s 77th Street central office building.

    ➤ Download this ringtone

  • GEdney-9 Panel Exchange

    ” alt=”77th Street Central Office” width=”500″ height=”221″ /> 77th Street Central Office – Home of the GEdney-9 Panel Exchange

    Recorded in 1977 by Ben Decibell – From  Evan Doorbell’s historic PhoneTrips library.

    The GEdney-9 Panel Exchange was installed in New York Telephone’s “77th Street” Central office, located at 7703 3rd Avenue in Brooklyn.

    GEdney-9 Panel Exchange

    [youtube http://www.youtube.com/watch?v=tG14OkSd8j0&rel=0]

    77th Street Central Office

    CLLI Code: NYCKNY77DS0

    Back in the day, the 77th Street Central office housed more than just the famous GEdney-9 Panel Exchange.


    GEdney-9 Dial Tone

    GEdney-9 was a wonderful panel exchange in New York City. Evan Doorbell’s PhoneTrips.com library has high quality recordings of calls dialed from this central office in the 1970’s. This next clip is a classic example of what is known as “Old City Dial Tone”. For dramatic effect, after about 50 seconds it transitions to another recording of dial tone, timing out; you can hear the panel revertive pulsing in the background as the call is connected to the permanent signal holding trunk. Ultimately, as the line is hung up, rich background sounds can be heard in this very high fidelity recording from Evan’s library:Can you hear how different from “Modern” dial tone it sounds? There’s a lot happening in the background. Here’s a side by side comparison of GEdney-9 dial tone versus “Modern” dial tone:

    In the image below, “Modern” dial tone appears in the top trace and GEdney-9 dial tone on the bottom:

    First of all, they’re based on different frequencies, so the the wavelengths are different. But look closely and notice that while the digitally-generated “Modern” tone waves are all perfectly smooth, GEdney-9’s all have slight bits of distortion; like snowflakes, no two are the same. That’s because the real GEdney-9 dial tone was not generated digitally; it came from large, rotating, motor-driven machinery. Background noise from the power supplies and the electromechanical switching equipment in constant operation added another, rich layer of character to the sound. You can really hear that influence of the background power supply noise when listening to the two side-by-side.

    1920’s Tone Generator
    1920s Ringing Machine

    —from PanelSwitchman‘s collection on Flickr.

    This is the type of rotating, electromechanical, tone generator and ringing machine that the GEdney-9 central office would have used.

  • Donna Summer – God Bless America

    God bless America, land that I love;
    stand beside her, and guide her,
    through the night with the light from above.
    From the mountains, to the prairies,
    to the ocean, white with foam,
    God bless America, my home sweet home;
    God bless America, my home, sweet home!