Real-time polyphonic octave doubling for the guitar

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master_Thuillier_Etienne_2016.pdf (12.11 MB)

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Volume Title

Sähkötekniikan korkeakoulu | Master's thesis
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Authors

Date

2016-04-04

Department

Major/Subject

Acoustics and Audio Signal Processing

Mcode

S3004

Degree programme

TLT - Master’s Programme in Communications Ecosystem (TS2005)

Language

en

Pages

66+7

Series

Abstract

This thesis studies digital signal processing solutions for enriching live guitar sound by way of mixing-in octave-doubled versions of the chords and melodies performed on the instrument in real-time. Following a review of techniques applicable for real-time polyphonic octave doubling, four candidate solutions are proposed, amongst which two novel methods: ERB-PS2 and ERB-SSM2. Performance of said candidates is compared to that of three state of the art effect pedal offerings of the market. In particular, an evaluation of the added roughness and transient alterations introduced by each solution in the output sound is conducted. The ERB-PS2 method, which consists in doubling the instantaneous phases of the sub-bands signals extracted with a constant-ERB-bandwidth non-decimated IIR filter bank, is found to provide the best overall performance amongst the candidates. This novel solution provides greatly reduced latency compared to the baseline pedals, with comparable, and in some case improved, sound quality.

Description

Supervisor

Välimäki, Vesa

Thesis advisor

Kargo, Jens Peter
Arknaes, Lars

Keywords

real-time, pitch-shifting, multi-resolution, sub-band, modulation, roughness

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https://urn.fi/URN:NBN:fi:aalto-201604201818

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[dipl] Sähkötekniikan korkeakoulu / ELEC