Session N Tuesday, May 15 8:30 - 13:00 hr Room C/D
Psychoacoustics, Perception and Listening Tests, Part 1
Chair: Nick Zacharov, Nokia Research Center, Tampere, Finland
8:30 hr N-1
An Investigation of
Interaural Time Difference Fluctuations. Part 1: The Subjective Spatial Effect
of Fluctuations Delivered over Headphones
Russell Mason, Bart
de Bruyn & Francis Rumsey
University of Surrey, Guildford, UK
The subjective spatial effect of noise signals with
sinusoidal ITD fluctuations was investigated. Both verbal and non-verbal
elicitation experiments were carried out to examine the subjective effect of
the ITD fluctuations with a number of fluctuation frequencies and fluctuation
magnitudes. It was found that the predominant effect of increasing the
fluctuation magnitude was an increase in the perceived width of the sound.
Paper 5383
9:00 hr N-2
A New Listener
Training Software Application
Sean Olive
Harman International, Northridge, CA, USA
A new computer-based listener training application is
described that trains listeners how to detect, classify and rate linear
distortions added to program material. All signal processing is performed
natively on the computer eliminating the need for expensive external hardware
or large sound file libraries of pre-processed signals. The software adapts to
the listeners' ability and performs automatic statistical analysis and storage
of the results on a database server. It provides a useful tool for selecting
the most discriminating and consistent listeners for listening tests and
product evaluation.
Paper 5384
9:30 hr N-3
Active Listening Room
Simulator: Part 1
Amber Naqvi &
Francis Rumsey
University of Surrey, Guildford, UK
The main objective of the 'active listening room' project
is to design a critical listening environment where the key acoustic features
of the room can be actively modified. The aim is to create a truly variable
listening condition in a reference listening room by means of active simulation
of key acoustic parameters such as the early reflection pattern, early decay
time and reverberation time. These parameters are likely to affect the
subjective assessment of reproduced sound quality in a listening environment.
Aims of the project are described, together with results of preliminary experiments.
Paper 5385
10:00 hr N-4
Evaluation of Five
Commercial Stereo Enhancement 3D Audio Software Plug-ins
Sean Olive
Harman International, Northridge, CA, USA
Objective and subjective measurements were conducted on
five commercial software-based plug-ins intended to provide spatial enhancement
of stereo reproduction at the computer workstation. Listeners rated the sound
quality of each using several different scales such as preference, timbral
balance, three different spatial attributes, audible distortion, in addition to
giving comments. Regular stereo (no enhancement) was included as a hidden
reference. The listening test results revealed clear winners and losers. Stereo
was preferred over three of the five plug-ins tested. The subjective results
tend to correlate with their measured frequency response.
Paper 5386
10:30 hr N-5
Perceptual and
Semantic Scaling for User-Centered Control over Distortion-Based Guitar Effects
William Martens &
Atsushi Marui
University of Aizu, Aizu-Wakamatsu, Japan
Multidimensional perceptual and semantic differential
analyses were performed for a set of stimuli that were generated by submitting
a pre-recorded guitar performance to a popular multi-effects processor. Within
three nominal types of distortion effect (Overdrive, Distortion and Fuzz), the
�drive� setting of the effect was varied between minimum and maximum levels
while adjusting the volume of the resulting sounds to maintain constant
loudness. As the meaning of the �drive� parameter varies across these effects,
changing the tone color for some, while changing only the loudness for others,
the loudness of the processor outputs was equalized prior to subjective rating
sessions in order to determine what perceptual attributes the �drive� parameter
affects besides loudness.
Paper 5387
11:00 hr N-6
Graphical Elicitation
Techniques for Subjective Assessment of the Spatial Attributes of Loudspeaker
Reproduction - a Pilot Investigation
Natanya Ford, Francis Rumsey & Bart de Bruyn
University of Surrey, Guildford, UK
Non-verbal elicitation techniques may be used in
addition to verbal methods in order to obtain meaningful subjective responses
about the spatial attributes of reproduced sound. By analyzing results from a
preliminary graphical investigation, the provision of such responses has been
appraised and practical considerations highlighted. Data analysis indicates
that non-verbal responses uphold conventional expectations with respect to the
effect of loudspeaker and listener location on perceived sound images. With
this in mind, it is suggested that the technique be used to assess variables
which have not been subject to such intensive study, or be employed in
situations where a verbal language may not be appropriate. Further
investigations are therefore proposed with respect to the findings of this
paper.
Paper 5388
11:30 hr N-7
An Investigation of
Interaural Time Difference Fluctuations.
Part 2: Dependence of the
Subjective Spatial
Effect on Audio Frequency
Russell Mason, Francis Rumsey & Bart de Bruyn
University of Surrey, Guildford,
UK
The effect of the audio frequency of narrow-band noise
signals with a sinusoidal ITD fluctuation was investigated. To examine this, a
subjective experiment was carried out using a match to sample method and
stimuli delivered over headphones. It was found that the magnitude of the
subjective effect is dependent on audio frequency and that the relationship
between the audio frequency and a constant subjective effect appears to be
based on equal maximum phase difference fluctuations.
Paper 5389
12:00 hr N-8
A Jitter Simulator on
Digital Data
Shogo Kiryu &
Kaoru Ashihara
Electrotechnical Laboratory, Tsukuba, Japan
A simulator is proposed to examine detection threshold of
the distortion due to time jitter. Signals with artificial time jitter are
simulated on digital data using over-sampling, interpolation, and decimation.
With this method, quantitatively controlled distortion is added to musical
signals and the signals can be presented to human subjects through a
conventional DA converter. The amount of the distortion hardly depends on the
equipment. We are examining detection threshold of time jitter. Preliminary
results show that some subjects can detect jitter of several hundreds
nanoseconds.
Paper 5390
12:30 hr N-9
Variance of Sweet
Spot Size with Head Location for Virtual Audio
John Rose, Boaz Rafaely, Takashi Takeuchi & Philip Nelson
University of Southampton, Southampton, UK
3D audio systems are
effective when the listener�s head location is close to the head location
assumed when the system was designed. In order to accommodate head movement, it
is possible to design 3D sound systems that continuously select appropriate
virtual audio filters that correspond to a listener�s varying head position.
The required spatial resolution of the audio filters depends on the size of the
sweet spot. Here the size of the sweet spot of a two speaker 3D audio system is
evaluated subjectively at symmetric and asymmetric head locations.
Paper 5391
