Jonathan Madden


Do we prefer music with ultrasonic content? “An investigation into the potential, positive or negative perceptual effect of frequencies above the audible range of hearing”.


Although it is generally acccepted that humans cannot perceive frequencies above 20kHz, recent research has shown that we can through bone conduction. This research has shown that frequencies above the audible range of hearing do have an affect on the brain. When compared with audible frequencies affect on the brain, the results are almost equal. Professor James Boyk of the Californian Institute of Technology, has shown that “one member of each instrument family Strings, Woodwinds, Brass and Percussion produces energy up to 40kHz or above”. Conventional audio equipment generally limits the frequencies which they can record and reproduce, from 20Hz to 20kHz. This stems from the 70’s when the compact disk was being created and storage mediums were very small. Limiting the frequencies saved space.   The question asked in this thesis was “Do we prefer music with ultrasonic content?” This was the idea that possibly, the reason we prefer going to a classical concert more than listening to the cd of that concert is because at the concert we also have ultrasonic content, produced from some of the instruments affecting our brain and perception of the music, whereas the cd does not have any ultrasonic frequencies.   In this study we aim to discern weather or not the ultrasonic content in music has a positive or negative impact on the listener. Tests were conducted in which 29 participants took part 15 women and 14 men. Each subject was shown 20 pairs of audio samples. One sample contained only audible frequencies, the other contained audible frequencies and ultrasonic frequencies. The results show that 51% of the time participants preferred the sample with ultrasonic and audible frequencies. 32% of the time they preferred the sample with just audible frequencies and 17% of the time they had no preference.   These results suggest that ultrasonic frequencies do have a positive perceptual affect and that the audio industry may be missing out by excluding these frequencies in their commercial recordings. Further and more detailed testing however is recommended.

Jonathan Madden