Name that percussive tune: Associative memory and amplitude envelope^†

† Supplemental materials including samples of sound sequences can be accessed at www.maplelab.net/memory.

ABSTRACT

A series of experiments demonstrated novel effects of amplitude envelope on associative memory, with tones exhibiting naturally decaying amplitude envelopes (e.g., those made by two wine glasses clinking) better associated with target objects than amplitude-invariant tones. In Experiment 1 participants learned associations between household objects and 4-note tone sequences constructed of spectrally matched pure tones with either “flat” or “percussive” amplitude envelopes. Those hearing percussive tones correctly recalled significantly more sequence–object associations. Experiment 2 demonstrated that participants hearing percussive tones learned the associations more quickly. Experiment 3 used “reverse percussive” tones (percussive tones played backwards) to test whether differences in overall energy might account for this effect, finding they did not lead to the same level of performance as percussive tones. Experiment 4 varied the envelope at encoding and retrieval to determine which stage of the task was most affected by the envelope manipulation. Participants hearing percussive tones at both encoding and retrieval performed significantly better than the other three groups (i.e., flat at encoding/percussive at retrieval, etc.). We conclude that amplitude envelope plays an important role in learning and memory, a finding with relevance to psychological research on audition and associative memory, as well as practical relevance for improving human–computer interface design.

KEYWORDS:

• Amplitude envelope
• Auditory perception
• Audition
• Memory
• Timbre
• Paired associates

Acknowledgements

The authors wish to thank Dennis Proffitt for his assistance and encouragement in designing these experiments, as well as Charissa Beaver, Andrew Carberry, Jose Dominguez, Annika van Hove, and Daniel Paris for their help in collecting the data.

Notes

† Supplemental materials including samples of sound sequences can be accessed at www.maplelab.net/memory.

1 However, studies have shown that music can aid memory (Simmons-Stern, Budson, & Ally, 2010; Wallace, 1994).

2 As our research in this paper is focused exclusively on amplitude envelope (rather than spectral envelope), for the sake of brevity we often use the term “envelope” for compactness.

3 Informal listening illustrated that percussive tones sounded shorter than flat tones of the same acoustic duration. A research assistant chose these values based on a desire to balance tone spacing, duration, and tempo in a “musical manner”.

4 In subsequent experiments we altered this approach using equal spacing between notes, demonstrating that differences in onset rate did not confound our results

5 Chance performance on old/new sequence recognition is 50%.

6 Dividing the number of correct sequence–object associations by the number of correctly recognized “old” sequences. With 10 objects, chance performance on the sequence–object association question is 10%

7 We chose a criterion of 70% based in part on the widely recognized limits in memory capacity with respect to the “magic number 7” (Miller, 1956). Had our goal been only to assess sequence object recall performance, a higher criterion for learning sequence–object associations—such as 100%— may have been preferable. However, this approach would be problematic for our goal of obtaining reliable measures of both sequence recognition as well as sequence–object recall. Even with only one exposure in the first experiment, performance on the sequence recognition task was around 70% for both conditions—after the distractor task. Requiring 100% performance on the sequence–object association task would have surely led to ceiling effects when assessing sequence recognition—undermining our ability to explore any potential differences in performance between the two measures across the four experiments.

8 This analysis used all 52 participants from the first two experiments, 34 from the third experiment (those in the percussive and flat conditions), and 40 from the fourth experiment (those in the percussive–percussive and flat–flat conditions).

9 A power analysis using the R package pwr reveals that given the effect size across these four experiments (d = 0.342), it would be necessary to run 270 participants to obtain 80% power for detecting an effect of envelope on sequence recognition.

Additional information

Funding

We would also like to acknowledge financial assistance for this research through grants to Michael Schutz from the Natural Sciences and Engineering Research Council of Canada [grant number NSERC RGPIN/386603-2010]; Ontario Early Researcher Award [grant number ER10-07-195]; McMaster University Arts Research Board; and the Canadian Foundation for Innovation [grant number CFI-LOF 30101].