A hybrid method for impulse response measurements with synthesized musical tones and Masked-MLS Stimuli
type: CreativeWork
description: Impulse responses or transfer functions are descriptions of acoustic and audio transmission channels, which completely characterise point-to-point propagation of sound in room acoustics or input-output relationships of linear systems in electroacoustics. Measurements of impulse responses or transfer functions are routinely carried out first to determine critical room acoustics parameters of enclosures such as concert halls, theatres and auditoria, or technical specification of electroacoustic transducers, i.e. loudspeakers and microphones. In room acoustics measurements, tradition techniques employ noisy testing signals as probe stimuli, which are unpleasant and intolerable to audiences. This hinders occupied measurements to be taken in many cases. Predicted in-use parameters from unoccupied measurements are known to be unreliable and problematic. It is also well appreciated in room acoustics research community that the use of musical or music-masked probe stimuli can mitigate problems of occupied measurements. It is therefore hypothesised as a starting point of this thesis that the use of musical tone like stimuli or musically masked testing signals can be used to determine impulse responses or transfer functions. Based on the above hypothesis, this thesis develops a new hybrid technique, in which narrow band linear chirps, called “presto-chirps” centred on musical notes are used to measure impulse responses in low to mid frequency bands, and music-masked maximum-length-sequences are deployed to obtain those in higher frequency bands. Broadband impulse responses are then obtained by combining the measured lower and higher frequency impulse responses. To test the hypothesis and identify the potential and limitations of the developed technique, mathematical formulation and analysis, computer simulations and real room measurements have been carried out and documented in this thesis. Investigation results show that purposely tailored and windowed narrow chirps that emu…
abstract: Impulse responses or transfer functions are descriptions of acoustic and audio transmission channels, which completely characterise point-to-point propagation of sound in room acoustics or input-output relationships of linear systems in electroacoustics. Measurements of impulse responses or transfer functions are routinely carried out first to determine critical room acoustics parameters of enclosures such as concert halls, theatres and auditoria, or technical specification of electroacoustic transducers, i.e. loudspeakers and microphones. In room acoustics measurements, tradition techniques employ noisy testing signals as probe stimuli, which are unpleasant and intolerable to audiences. This hinders occupied measurements to be taken in many cases. Predicted in-use parameters from unoccupied measurements are known to be unreliable and problematic. It is also well appreciated in room acoustics research community that the use of musical or music-masked probe stimuli can mitigate problems of occupied measurements. It is therefore hypothesised as a starting point of this thesis that the use of musical tone like stimuli or musically masked testing signals can be used to determine impulse responses or transfer functions. Based on the above hypothesis, this thesis develops a new hybrid technique, in which narrow band linear chirps, called “presto-chirps” centred on musical notes are used to measure impulse responses in low to mid frequency bands, and music-masked maximum-length-sequences are deployed to obtain those in higher frequency bands. Broadband impulse responses are then obtained by combining the measured lower and higher frequency impulse responses. To test the hypothesis and identify the potential and limitations of the developed technique, mathematical formulation and analysis, computer simulations and real room measurements have been carried out and documented in this thesis. Investigation results show that purposely tailored and windowed narrow chirps that emu…
author: Serafini, Massimo
language: en
date published: 2026
date modified: 2026-07-24T04:26:41Z
provider: U. of Salford
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: U. of Salford