Discrimination of Data-Reduced Sustained Musical Instrument Tones

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Discrimination of Data-Reduced Sustained Musical Instrument Tones"

By

Mr. Chung LEE


Abstract

We know that musical instrument tones are recognizable even if they are 
altered. The current study investigates the perception of musical 
instrument tones altered by two data reduction methods: MP3 compression 
and piecewise linear approximation (PLA) of additive synthesis amplitude 
envelopes. Sustained musical instrument tones were data-reduced using the 
above methods to determine how the detection of data-reduced tones varies 
with instrument and the degree of data reduction. Sounds with 
harmonically-flattened frequencies were compressed by MP3 compression and 
PLA of amplitude envelopes. Listeners were asked to discriminate the 
altered sounds from reference sounds resynthesized from the original data. 
This allowed us to determine which degree of data reduction produces 
near-perfect, (above 90%), moderate (around 75%), and poor discrimination 
(around 50-60%). Statistical analysis showed that discrimination was 
different from instrument to instrument. Discrimination scores were 
strongly correlated with a number of spectral measurements of the original 
tone. Objective error metrics including relative spectral error were 
compared for their correspondence with the discrimination scores. Other 
than discrimination, multidimensional scaling (MDS) was done to search for 
salient timbral attributes other than spectral centroid and attack time. 
In addition to that, in follow-up work we plan to do a study where 
listeners will be asked to rate the dissimilarity between the 
MP3-compressed instrument tones. MDS solutions of the compressed 
instrument sounds and the originals will be compared to determine if MP3 
compression causes significant impact on instruments・ relative positions 
within the timbre space.


Date:			Thursday, 18 August 2011

Time:			2:00pm – 4:00pm

Venue:			Room 3588
 			Lifts 27/28

Chairman:		Prof. Philip Mok (ECE)

Committee Members:	Prof. Andrew Horner (Supervisor)
 			Prof. Jogesh Muppala
 			Prof. David Rossiter
                      	Prof. Richard So (IELM)
                         Prof. Lonce Wyse (National Univ. of Singapore)


**** ALL are Welcome ****