frequency-place-transformation

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Presentation for the "Models of Auditory Perception Seminar". This presentation is about the auditory system and, in particular, the inner ear. After explaining the mechanics of the cochlea in details, I am focusing on the Frequency-Place-Transformation, which takes place along the basilar membrane. This process is then closely connected to the so-called auditory filters and the masking effect. Finally, I am comparing how all these different scales are related to each other.

TRANSCRIPT

Frequency-Place Transformation AIPA: Models of Auditory Perception Seminar

20 November 2014

The speaker

Francesco Bonadiman franzbona@hotmail.it

Computer Science

Bachelor @UniTN (Trento, IT)

2/29

The speaker

Francesco Bonadiman franzbona@hotmail.it

Computer Science

Bachelor @UniTN (Trento, IT)

2/29

The speaker

Francesco Bonadiman franzbona@hotmail.it

Computer Science

Bachelor @UniTN (Trento, IT)

2/29

The outer ear

3/29

The outer ear

3/29

[Raake2014]

The outer ear

3/29

[Raake2014]

catalyzes the sound

The outer ear

3/29

[Raake2014]

catalyzes the sound

The middle ear

[Raake2014]

4/29

The middle ear

[Raake2014]

4/29

The middle ear

[Raake2014]

3 smallest bones in the body

4/29

[Blausen2014] 5/29

2 membrane- covered openings

[Blausen2014] 5/29

2 membrane- covered openings

[Blausen2014] 5/29

2 membrane- covered openings

[Blausen2014] 5/29

2 membrane- covered openings

[Blausen2014] 5/29

2 membrane- covered openings

opposite directions

How it works [Kidsdiscover2014]

6/29

How it works [Kidsdiscover2014]

6/29

difference of sound pressure

How it works [Kidsdiscover2014]

acoustic energy (air) → fluid oscillations

6/29

difference of sound pressure

How it works [Kidsdiscover2014]

impedance matching

acoustic energy (air) → fluid oscillations

6/29

difference of sound pressure

The inner ear

[Amplifon2014] 7/29

The inner ear

[Amplifon2014] 7/29

The inner ear

[Amplifon2014] 7/29

The cochlea: traditional view

8/29

The cochlea: traditional view

[Zwicker,Fastl2007] 8/29

The cochlea: traditional view

[Zwicker,Fastl2007] 8/29

The cochlea

[Wierstorf2014] 9/29

The cochlea

[Wierstorf2014] 9/29

2½ turns for saving space

The cochlea

[Wierstorf2014]

[RobinsonLibrary2014]

9/29

2½ turns for saving space

32 mm “unwound”

The cochlea

[Wierstorf2014]

[RobinsonLibrary2014]

[Wikipedia2014] 9/29

2½ turns for saving space

32 mm “unwound”

The cochlea

[Wierstorf2014]

[RobinsonLibrary2014]

[Wikipedia2014] 9/29

2½ turns for saving space

32 mm “unwound”

The cochlea

[Wierstorf2014]

[RobinsonLibrary2014]

[Wikipedia2014]

helicotrema 9/29

2½ turns for saving space

32 mm “unwound”

Channels and membranes

[Flanagan1972] 10/29

Channels and membranes

[Flanagan1972] 10/29

Channels and membranes

[Flanagan1972] 10/29

hydromechanically → single unit

Channels and membranes

[Flanagan1972] 10/29

Channels and membranes

[Flanagan1972] 10/29

fluids = oscillations

Overview [WhatWhenHow2014]

11/29

Overview [WhatWhenHow2014]

11/29

O H R

Overview [WhatWhenHow2014]

11/29

O H R

Is this enough?

12/29

Organ of Corti

[MixBag2014]

13/29

Organ of Corti

[MixBag2014]

13/29

Organ of Corti

[MixBag2014]

13/29

membranes excitation → nervous impulses (firings)

Organ of Corti

[MixBag2014] [Zwicker,Fastl2007]

13/29

membranes excitation → nervous impulses (firings)

Organ of Corti

[MixBag2014] [Zwicker,Fastl2007]

13/29

membranes excitation → nervous impulses (firings)

Organ of Corti

[MixBag2014] [Zwicker,Fastl2007]

13/29

IHC → brain OHC → tuning

membranes excitation → nervous impulses (firings)

14/29 [GalleryHip2014]

14/29

membranes shearing → HC-cilia → nerve fibers

[GalleryHip2014]

15/29

Frequency-Place-Transformation

[Mandel, Ellis2009] 16/29

Frequency-Place-Transformation

[Mandel, Ellis2009] 16/29

Frequency-Place-Transformation

[Mandel, Ellis2009] 16/29

Frequency-Place-Transformation

[Mandel, Ellis2009] 16/29

BM = kind of Fourier Analysis

Waves and peaks

[Moore2013] 17/29

Waves and peaks

[Moore2013] 17/29

Waves and peaks

[Moore2013] 17/29

Waves and peaks

[Moore2013] 17/29

spatial envelope

Waves and peaks

[Moore2013] 17/29

place + growth ← frequency

spatial envelope

Waves and peaks

[Moore2013] 17/29

place + growth ← frequency

spatial envelope

Waves and peaks

[Moore2013] 17/29

place + growth ← frequency

spatial envelope

Waves and peaks

[Moore2013] 17/29

place + growth ← frequency

spatial envelope

Characteristic Frequencies

[Zwicker,Fastl2007] 18/29

Characteristic Frequencies

[Zwicker,Fastl2007] 18/29

BM’s maximum displacement

Characteristic Frequencies

[Zwicker,Fastl2007] 18/29

BM’s maximum displacement

Mechanical Reasons [Skidmore.edu2014]

19/29

Mechanical Reasons [Skidmore.edu2014]

19/29

stiff thick narrow < 0.1 mm

Mechanical Reasons [Skidmore.edu2014]

19/29

stiff thick narrow < 0.1 mm

flexible thinner wider ∼0.5 mm

Mechanical Reasons [Skidmore.edu2014]

19/29

stiff thick narrow < 0.1 mm

flexible thinner wider ∼0.5 mm

[Wikipedia2014]

Mechanical Reasons [Skidmore.edu2014]

[Wikipedia2014] 19/29

stiff thick narrow < 0.1 mm

flexible thinner wider ∼0.5 mm

Von Békésy (1947) Pioneering work Light microscope

Human cadaver ear

20/29

Masking

21/29 [Wikipedia2014]

Masking

21/29

shows the limits of frequency selectivity (FPT)

[Wikipedia2014]

Masking

21/29

shows the limits of frequency selectivity (FPT)

auditory system → not distinguish between frequencies

[Wikipedia2014]

Masking

21/29

shows the limits of frequency selectivity (FPT)

depends on both signal and masker

auditory system → not distinguish between frequencies

[Wikipedia2014]

Masking

21/29

Detailed talk about it

shows the limits of frequency selectivity (FPT)

depends on both signal and masker

auditory system → not distinguish between frequencies

[Wikipedia2014]

Fletcher Experiment

22/29 [Wikipedia2014]

Fletcher Experiment

22/29 [Wikipedia2014]

masker = 65 dB

masked = 40 dB

Fletcher Experiment

22/29 [Wikipedia2014]

masker = 65 dB

masked = 40 dB

NO!

Fletcher Experiment

22/29 [Wikipedia2014]

masker = 65 dB not masked = 55 dB

masked = 40 dB

NO!

Fletcher Experiment

22/29 [Wikipedia2014]

masker = 65 dB not masked = 55 dB

masked = 40 dB

NO! YES!

Fletcher Experiment

22/29 [Wikipedia2014]

masker = 65 dB not masked = 55 dB

masked = 40 dB

NO! YES!

detect the shape of the so-called

Auditory Filters

Auditory Filters (Critical Bandwidth) [AcousticLab.org2014]

[Wikipedia2014] 23/29

Auditory Filters (Critical Bandwidth) [AcousticLab.org2014]

[Wikipedia2014] 23/29

USUALLY: sounds located singularly

limited range of frequencies different center frequency

Auditory Filters (Critical Bandwidth) [AcousticLab.org2014]

[Wikipedia2014] 23/29

USUALLY: sounds located singularly

limited range of frequencies different center frequency

MASKING: single, broader maximum signal perceived as one same critical bandwidth

BM frequency selectivity = fail

Critical-band Rate Scale

[Zwicker,Fastl2007]

24/29

Critical-band Rate Scale

[Zwicker,Fastl2007]

24/29

new unit leading to critical-band rate scale

Critical-band Rate Scale

[Zwicker,Fastl2007]

24/29

boundaries of the critical bands

new unit leading to critical-band rate scale

Critical-band Rate Scale

[Zwicker,Fastl2007]

24/29

boundaries of the critical bands

new unit leading to critical-band rate scale

audible frequency range in 24 bands

Critical-band Rate Scale

[Zwicker,Fastl2007]

25/29

Critical-band Rate Scale

[Zwicker,Fastl2007]

25/29

from 0 to 24 unit = Bark

(linear)

Critical-band Rate Scale

[Zwicker,Fastl2007]

25/29

higher frequency = bigger amplitude = broader filters from 0 to 24

unit = Bark (linear)

Critical-band Rate Scale

[Zwicker,Fastl2007]

25/29

higher frequency = bigger amplitude = broader filters

mechanical reasons of the membrane

(rigid = high frequencies)

from 0 to 24 unit = Bark

(linear)

Back to the Cochlea

[Zwicker,Fastl2007]

26/29

Back to the Cochlea

[Zwicker,Fastl2007]

26/29

GOLDEN RULE: FPT → Inside our ear, frequencies are mapped onto certain locations

Back to the Cochlea

[Zwicker,Fastl2007]

26/29

SILVER RULE: Mapping not linear but ∼linear up to 500 Hz ∼logarithmic above

GOLDEN RULE: FPT → Inside our ear, frequencies are mapped onto certain locations

27/29

28/29

References ● Brian C.J. Moore, 2003 - An introduction to the psychology of hearing, 6th Edition

● Zwicker and Fastl, 2007 - Psychoacoustics: facts and models, 3rd edition

● Mandel, Ellis, 2009 - Speech & Audio Processing & Recognition - Lecture 4

● Other slides and scripts from professors Raake and Möller

● Huge help given by www.google.com/imghp to find images and references

29/29

AcousticLab.org: 23 Amplifon: 7 Blausen: 5

Flanagan: 10 GalleryHip: 14 Kidsdiscover: 6

Mandel, Ellis: 16 MixBag: 13 Moore: 17

Raake: 3, 4 RobinsonLibrary: 9 Skidmore.edu: 19

WhatWhenHow: 11 Wikipedia: 9, 19, 21, 22, 23 Wierstorf: 9

Zwicker, Fastl: 8 13 18 24 25 26

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