The K Music Assist Device (K-MAD) was invented and built for this experiment. K-MAD is a tactile sound device that divides the sound spectrum into multiple frequency ranges and uses vibrating speakers to apply these ranges through multiple points of contact to a user’s body. K-MAD has six outputs with preset frequency ranges. The vibrating speakers convert music into vibrations. Two devices enabled a stereo effect during parts of testing.
Fourteen subjects were tested: two with normal-range hearing and twelve with significant hearing loss, six with cochlear implants and six with hearing aids. Both hearing-loss groups had one subject over 65 years old.
Subjects were asked to listen to song Penny Lane by the Beatles throughout testing until K-MAD optimal position was set. Then 4 other musical pieces tested.
1. Subjects asked to set hearing device to normal everyday setting.
2. Using regular speakers, baseline hearing measured: lowest perceptible volume.
3. Using regular speakers, “quality” hearing measured: comfortable level of song volume.
4. Using House Ear Institute test, subjects’ tone discrimination, pitch discrimination and volume hearing capability measured.
5. Final baseline: song perception. Using regular speakers, thirty seconds of Penny Lane at “quality” level. Rating from 1 to 10, described as “One is barely hearing song,” and “ten is an excellent experience hearing song.”
Since K-MAD is an original device, it was unknown which body parts would respond best to vibrations. For users’ practicality, fingers, sternum, and back of the neck were tested. K-MAD uses same sound source as the regular speakers, at same “quality” volume level, but using vibrating speakers.
6. Individual body part: Subjects give 1-10 rating as each frequency-range is individually tested on each finger of each hand (dominant hand first), sternum and back of neck.
7. Three Fingers. Most sensitive three fingers on sensitive hand tested simultaneously at best frequency ranges. Then speakers rotated on those three fingers. 1-10 for each attempt.
8. Full hand. Five fingers on one hand simultaneously with lowest 5 frequency ranges.
9. Two hands. Best frequency ranges on three most sensitive fingers on sensitive hand and same frequencies on three most sensitive fingers on the other hand. 1-10.
10. Two hands again. Full sound spectrum with three best frequencies on the sensitive hand and three remaining frequencies on sensitive fingers of other hand. 1-10.
11. Two hands and Sternum. Five speakers on most sensitive five fingers and one on sternum (or back of neck) with best frequency. 1-10.
Subject’s optimal combination for tactile sound on the K-MAD is now known.
12. Penny Lane played for one minute on regular speakers, but now with K-MAD in optimal position. Tester plugs, unplugs K-MAD so subject can sense effects. 1-10.
13. Two more songs, two classical pieces. Subjects asked to hum melody, tap beat and identify lyrics. Pieces: New York New York, Frank Sinatra (strong male voice, orchestra), Stop Your Sobbing, Pretenders (strong female voice, rock band), Mozart’s Violin Concerto 3 (strings, orchestra), Rachmaninov’s Piano Concerto 2 (piano, strings, orchestra).
Experiment averaged 2.5 hours.