Instead of a D.J., a Web Server Names That Tune
Instead of a D.J., a Web Server Names That Tune
By ANNE EISENBERG
A SONG and its name are easily parted, as anyone knows who has
listened to a tune on the radio and then waited in vain for the
announcer to identify it.
Now some companies are using a technology that can name that tune as
it plays, promptly displaying words like "Take Five by the Dave
Brubeck Quartet" in text on an Internet radio or cellphone.
The systems are sensitive enough to identify not only names and
artists within a vast range of recorded music, but also different
versions of a piece done by the performers, even when the differences
At the recent Consumer Electronics Show in Las Vegas, for instance,
Royal Philips Electronics demonstrated a prototype of an Internet
radio that was not only capable of naming the band Pearl Jam as its
music streamed past but also distinguishing a version of a tune that
it played at a concert in Verona, Italy, from the same tune recorded
"To our ears the two versions sound the same," said Ton Kalker, a
mathematician at Philips Research in Eindhoven, the Netherlands, who
led the team that developed the rapid identification system. "But the
technology is sensitive enough to make a distinction."
The technology that spots the mystery tune in products from Philips
and other companies is called audio fingerprinting. It is based on the
premise that every performance of a song has unique audio
characteristics - for example, a certain relationship of neighboring
high and low notes over a minuscule slice of time. Represent those
relationships in numbers, and you have a code that shows a particular
version of a song, and no other.
"Audio fingerprinting works by creating a mathematical description of
some of the unique features of a song," said Dr. Richard Gooch, deputy
director of technology at the International Federation of the
Phonographic Industry, a trade organization based in London. The
fingerprints are stored on a server. When the server is asked to
identify a tune - for instance, a song playing on Internet radio -
software matches a snippet of the tune, expressed in code, with the
whole coded version of the song stored on the server.
Some companies offer fingerprinting technology to identify not only
streaming content but the contents of audio files and traditional
radio broadcasts as well, Dr. Gooch said. His group and the Recording
Industry Association of America have recently investigated many audio
fingerprinting systems to see if they might benefit the recording
Dr. Gooch said that the technology stood up even to the most difficult
conditions - poor loudspeakers, highly compressed streaming files or
broadcasters who speed up songs slightly to make room for commercials.
"We've found that even when broadcasters tweak a song or compress it,"
he said, "so long as you can still hear it, the systems can extract a
description of unique characteristics in the song," quickly matching
the description with the database to identify the track.
The steadily improving technology has been used commercially in
business applications since at least the early 80's, he said, for
example, in the music business to identify broadcast performances and
then pay royalties to rights holders. Given the popularity of digital
music, consumer applications of the technology are probably
inevitable, Dr. Gooch said.
"Audio fingerprinting is accurate, robust and runs in a sensible
amount of time," he said. "It really works."
Shazam Entertainment, based in London, already offers British
consumers an audio fingerprinting service linked to cellphones. Users
dial the service and then hold their phones up to the tune that is
playing, say, on the car radio. Shazam has a database with
fingerprints of 1.6 million tunes. It matches the incoming fingerprint
with its database and within 30 seconds sends a text message back to
the phone identifying the song.
"We have most any popular song that has been recorded," said Philip
Inghelbrecht, founder of the company and director of its content. "So
long as the CD is commercially available, we will have it."
In the future, manufacturers of electronic devices may offer audio
fingerprinting to people who want to organize music collections stored
on their hard drives, said Vance Ikezoye, chief executive of Audible
Magic, a company in Los Gatos, Calif., that offers its own patented
audio fingerprinting technology. "It's hard to manage music if you
don't have the correct information for every song in your collection,"
Companies have used different techniques to create the unique code
that constitutes a fingerprint. At Philips, for example, Dr. Kalker
said, he and colleagues created the code by breaking each tune into
10-millisecond snippets. Then they calculated the differences in the
loudness of adjacent frequencies in the snippet and how those
differences changed over time. They repeated the process every 10
milliseconds to extract code over the entire length of the song.
Then, when an Internet radio detected the song streaming through it,
it sampled the song and sent the sample along for pattern-matching.
"The whole process takes about three seconds," he said. "So even a
dumb AM or FM receiver can tell you a lot about what you are listening
Dr. Gooch suggested that fingerprinting systems would eventually be
common on car radios. "When every car has its own digital audio
player," he said, "people will want to know the name of the song they
are listening to displayed on the dashboard."
Mr. Ikezoye of Audible Magic said that people who used the company's
system need not worry about violating the rights of music publishers.
Although Audible Magic maintains a big database of popular copyrighted
music, he said, the fingerprints are not the actual songs, but
summaries of factual measurements describing the sound. "The original
sound can't be reconstructed from the fingerprint," he said, "so
storing and sharing fingerprints does not represent an infringement of
If the technology catches on in consumer applications, radio listeners
may one day have an antidote to a common problem cited by Cary
Sherman, president and general counsel of the Recording Industry
Association of America: "Radios often don't bother to tell listeners
what they have played," he said simply.