Music of the Heart
The Music of the Heart was an interactive hands-on exhibit at the
Boston Museum of Science based on a collaboration between Boston
University's Center for Polymer Studies Science Education Group and Beth
Israel Deaconess Medical Center's ReyLab.
The "heart music" is derived from electrocardiogram (ECG) data—
actual digital recordings of the electrical signals of the human heart.
The hands-on exhibit at the Boston Museum of Science allowed
museum-goers to hold onto bars to record their own electrocardiogram of
approximately 25 beats and, in real time, listen to the 'music' it
produced. Heart music you would hear at the museum exhibit, based only
on mapping the raw data to pitches, sounds something like this:
The Music of the Heart was featured in The Sacred Balance TV series
where you can find the Heartsongs Online Game allowing visitors to
hear recordings similar to those created in real-time at the hands-on
Data from overnight electrocardiogram recordings were also used to
create music. The audio CD HeartSongs accompanied the exhibit.
These heart songs began as musical notes mapped from the heartbeat data.
The composer then added harmonies and rhythm to make pleasant sounding
Listen to these "composed" heart songs. Can you tell which compositions are based on "healthy"
heart data? Hint: read below.
How can your heart make music?
In the first of four stages, we obtained digital tape recordings of
the heartbeat using a Holter monitor, a pocket-sized ECG recorder that
can store thousands of consecutive heartbeats (as shown in the figure)
over an entire day.
Next, using a computer, we measured the precise
intervals between the heartbeats, creating a graph of the
instant-to-instant changes in heart rate as a function of time.
While your pulse may feel perfectly regular, you actually have a
great deal of subtle variability from one beat to the next. These
fluctuations are produced by the normal functioning of the involuntary
nervous system, which can cause your heart to slow down or speed up.
The normal heartbeat, therefore, does not follow a metronomic or
march-like beat–suprisingly, it has a dance-like plasticity and
The third step in creating these heartsongs was to convert the time
intervals between heartbeats into integers. We used a simple computer
program to generate roughly 330 integers per data set. We started with
100,000 recorded heartbeats (roughly a 24 hour period), then calculated the average of every 300
beats. We averaged the beats to remove very short-term fluctuations
caused by movement or breathing.
The product of these musical mappings raises a fundamental question.
Why does the healthy heart create musically pleasing or interesting note
sequences, whereas the diseased heart create boring repitition?
The answer may lie in the origin of heart rate variability regulated
by our nervous systems. The result is a complex pattern of variations
present in normal heartbeats but absent in sick heartbeats that have
been shown to have the mathematical structure of a fractal; see
our Patterns in Nature
The term fractal describes objects such as snowflakes and coral
formations, which are composed of smaller units resembling the larger
scale form–a property called self-similarity. Fractals have been
shown to be relevant to a wide range of natural phenomena. This term
also applies to complex processes that are made up of different
frequency components with a special type of scaling relationship to each
other. Work by Richard Voss and John Clarke have shown that some
classical music has this type of scaling pattern.
These recordings are, to our knowledge, the first effort to use actual
rhythms of the heart as the template for musical composition.
The musicality of these recordings raises a further question: could
the composition of music involve, at least in part, the
re-creation by the mind of the body's own naturally complex
rhythms and frequencies? Perhaps what the ear and the brain perceive as
pleasing or interesting are variations in pitch that resonate with or
replicate the body's own complex (fractal) variability and scaling.
The musical pieces recorded here cannot resolve this question, but
may challenge the imagination and delight the ear.
Explore Further: If you would like to replicate this
experiment and create your own music, you can download heart-rate time
series from PhysioNet. MP3 audio files are available by request
(see contact below).
The Music of the Heart involved the contributions of several
individuals, including C.-K. Peng, Ary Goldberger, and Zach Goldberger
(Beth Israel), Gene Stanley and Paul Trunfio (Boston University) and
Steve Burns (MIT).
For more information, please contact Paul Trunfio (or e-mail firstname.lastname@example.org).
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