learning and memory

Recalling associations between sights and sounds helps us understand unseen events and aids our comprehension of our environment.  Can the property of amplitude envelope play a role in this basic task?  Our series of experiments suggests sounds with natural amplitude envelopes (i.e. percussive tones) are easier to associate with target objects than sounds with artificial envelopes (i.e. flat tones). 

Along with Jeanine Stefanucci and her students Amber Roth and Andrew Carberry, we arranged these individual tones into random 4-note melodies. Participants then heard these melodies, associating them with arbitrarily assigned common household objects such as car keys, a remote control, camera, etc.  When later tested on these associations, we observed interesting differences in the number of tone sequence-object associations recalled.  Participants hearing sequences with percussive tones recalled significantly more of their associated objects.

Click below to hear samples of the percussive, flat, and reverse-percussive sequences used in this experiment. Some of our key findings are summarized in the figure on the right panel, and images of target objects like the ones used in this study appear below. Click here for more information on our amplitude envelope research, including it’s important role in triggering the unity assumption.

Percussive Tone

Percussive envelopes are characterized by an abrupt onset followed by an immediate exponential decay.

Flat Tone

Flat envelopes are characterized by an abrupt onset, an indefinite sustain period and an abrupt offset.

Reverse Percussive Tone

Reverse envelopes are characterized by an exponential ramp up followed by an abrupt offset.

Amplitude Envelope