Author(s): Madison M. Ward, Kellyn Barrow, Katharine A. Tesar, Samantha Brooks, Chaoran Li
Mentor(s): Lynn H. White
Institution SUU
Analog recordings (e.g. vinyl records, cassette tapes) create sound waves that are identical to the live sounds they recorded. These sound waves are continuous and sinusoidal. Conversely, digital recordings start off as analog, but they are then converted to binary code. Stored often as mp3 or wav files, the playback device converts them back to analog so that the brain can process the signal. Importantly, the sound waves emitted from digital devices (e.g. smartphones, PCs, modern TVs) are unlike live sounds. These sound waves are discrete and follow a square wave pattern. To date, no one except our lab has investigated the effect of digital vs analog sound on any dependent variable, in humans or in animals. Previously, we showed that digital recordings of the song Lean on Me produced different effects on autonomic activity compared to analog recordings of the same song. Specifically, the digital recording 1. had no effect on skin conductance whereas analog recordings decreased it, 2. increased heart rate whereas analog recordings had no effect, and 3. failed to increase heart rate variability as much as the analog recording did (manuscript in progress). These results suggest that digital recordings increase sympathetic nervous system activity and detract from overall well-being. The present study tested the effect of two different recording types (digital and analog) of a nature sound on skin conductance (SC), heart rate (HR) and heart rate variability (HRV), as well as mood, aggression, and empathy. We connected participants to a Biopac MP36 system to record the physiological measures of sympathetic nervous system activity. After a five-minute baseline, they completed the PANAS mood questionnaire. Next, they were randomly assigned to hear a babbling brook on either a cassette tape or an mp3 player. After listening to the brook for five minutes, they completed the PANAS again. This was followed by a state aggression questionnaire, and a questionnaire to measure state empathy. The sound of the brook continued until the last questionnaire was finished. We hypothesized that compared to analog, digital recordings will 1. increase SC, 2. Increase HR, 3. decrease HRV, 4, decrease mood, 5. Increase state aggression, and 6. decrease state empathy. So far, only the PANAS surveys have been analyzed and preliminary results show that digital sound significantly decreased positive mood, whereas analog sound had no effect on mood.