ear and head dimensions measurement and experiment design of hrtf measurement supervisor: dr richard...
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Ear and head dimensions measurementEar and head dimensions measurementandand
Experiment design of HRTF Experiment design of HRTF measurementmeasurement
Supervisor: Dr Richard SoSupervisor: Dr Richard SoSpeaker: Brian NganSpeaker: Brian Ngan
ContentsContents• Introduction• Ear and Head dimensions of 1059 UG students
– Motivation– Data collected– Methodology of measurement– Next step
• Experiment design of HRTF measurements– Motivation– Preparation of Manikin head– Preparation of external ear model– Design of experiment
• Summary• Q & A
IntroductionIntroduction• Sound Localization of human
– Filtering effect of pinna, head and torso – Brain process those data and percept an
auditory event
• Head-related Transfer function (HRTF)– Frequency responses and time delay
between sounds that originate from different positions and their corresponding destination of sounds measured between the ear canals and the pinnae
IntroductionIntroduction• The shape of ear and head is highly
correlated to Head-Related Transfer Function (HRTF)
• Clustering people according to their ear and head dimensions
Ear and Head Ear and Head dimensions of dimensions of
1059 UG 1059 UG studentsstudents
MotivationMotivation• Study the relationship between
ear/head dimensions and sound localization performance
• Cluster subjects and collect a set of HRTF from each cluster
Ear and Head measurements
Data collectedData collected• 1059 UG students• 610 males, 449
females• Head dimensions
– Chin to top of head– Bitragion Breadth– Head Length
Ear and Head measurements
• Ear dimensions– d1 cavum concha height– d2 cymba concha height– d3 cavum concha width– d4 fossa height– d5 pinna height– d6 pinna width– d7 intertragal incisure
width
Ear and Head measurements
Data collectedData collected
From V. R. Algazi et. al. (2001)
Methodology of Methodology of measurementmeasurement
• Head measurement– Using anthropometer to measure
Ear and Head measurements
Methodology of Methodology of measurementmeasurement
• Ear measurement– Using digital
camera to take ear photos
– Measure different dimensions with a program provided by Mr. Leung Wai Keen
Ear and Head measurements
Methodology of measurementMethodology of measurementEar and Head measurements
The program that used for ear measurement
Next step….Next step….• The progress: ear measurement• Cluster subjects according to their
ear/head dimensions• Invite students from each cluster to
be subjects of sound localization performance experiment
• Check if the sound localization performance is different in different cluster
Ear and Head measurements
Next step….Next step….• Collect 1 or 2 subjects’ ear models
from each cluster• Measure sets of HRTF from those ear
models• Verify those HRTFs if it gives a good
sound localization performance for people belonged to that cluster
Ear and Head measurements
Experiment Experiment design of HRTF design of HRTF measurementsmeasurements
MotivationMotivation• Investigate the effect of head size on
HRTF• Investigate which type of material
(wax or ABS) is more suitable for making HRTF-measurement-purpose manikin head
• Investigate the differences of HRTF between human and manikin head with ear model
Experiment design of HRTF measurements
Preparation of Mannequin Preparation of Mannequin headhead
• Dimensions:– 5%tile, 50%tile and 95%tile of head
height, breath and length of male data collected in UST
– Using rapid prototype machine to make the model• FDM – ABS (a kind of polymer)• ThermoJet – Wax
Experiment design of HRTF measurements
Experiment design of HRTF measurements
Preparation of external ear Preparation of external ear modelmodel
• Dr. Aaron Leung (certified prosthetist-orthotist) helped making external ear model
• Ear models are made of silicon• 2 sets of external ear models were made now
(Brian’s and Dr. So’s) Will invite 2 more subjects.
Experiment design of HRTF measurements
Design of experimentDesign of experiment• Due to limitation of time, it may only
possible to collect 20 set of HRTF• Material deciding : 1,2,3• Head size effect: 1,7,8• Individual difference: 1,4,5,6
Experiment design of HRTF measurements
Wax ABS
95%til
e50%til
e 5%tile95%til
e50%til
e 5%tile Real
Brian 7 1 8 15 2 16 3
Ear Dr So 9 4 10 20 17 21 -
Subject 1 11 5 12 22 18 23 -
Subject 2 13 6 14 24 19 25 -
*Numbers are the working sequence
Design of experimentDesign of experiment• What I am expecting:
– Wax head will give nearer values of real man HRTF than ABS
– The head size does not affect too much on HRTF
– The shape of external ear (pinna) contributes most part of HRTF
– HRTF collected will give high sound localization performance to its owner
Experiment design of HRTF measurements
SummarySummary• We have collected 1059 students’
head dimensions and ear photos• We are going to
– test which material is the best for HRTF measurement
– Test the differences of HRTF collected with human and manikin head
Q & AQ & A