Audio Optica, Channel Free

8/2/2019 Audio Optica, Channel Free

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1. To make important sounds audible andcomfortable by providing: – frequency specific amplification

– level specific amplification

1. Maximize speech understanding

1. Provide high sound quality

Goals of Amplification

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary



• First instruments were single channel with

some frequency shaping• Good sound quality, but reduced flexibilityto fit varying dynamic ranges and non-linear targets

Single Channel

Channels

ChannelFreeTM


Benefits of Speed

Summary



• Multiple channels were developed thatwere finally able to achieve frequency andlevel-dependent amplification

• BUT these systems didn’t always soundso good

Multiple Channels

Channels

ChannelFreeTM


Benefits of Speed

Summary



• Why didn’t it sound so good?

• Gain in each channel was varied based on thefrequency and intensity of the signal

• With fast time constants, the contrast between thepeaks and valleys of the signal are reduced (i.e. itspectrally smears)

Amplified

with many

channel

system

Original

vowel /ee/

F1

F2

F3

Multiple Channels

40

50

60

70

90

80

Key

O u t p u t ( d

B

S P L )

Frequency (Hz)

500 350030002500200015001000 4000 4500 5000 5500 6000

Channels

ChannelFreeTM


Benefits of Speed

Summary



• So the engineers thought again andfound...

• It was possible to achieve less signaldegradation via two mechanisms:

Multiple Channels

Slower time constants in eachchannel

Overlapping channels

Channels

ChannelFreeTM


Benefits of Speed

Summary



slow

Number of channels

S p e e d o

f c o m p

r e s

s i o n

fast

low high

Equal sound

quality

Slow time constants & multiplechannels

Channels

ChannelFreeTM


Benefits of Speed

Summary



• Loss of audibility of soft consonants

• Errors of undershoot and overshoot

Slow time constants - Drawbacks

Channels

ChannelFreeTM


Benefits of Speed

Summary



• Channels no longer act independently

• They take into account more of what ishappening in their adjacent channels

Overlapping Channels

Frequency (Hz)

I n t e n s

i t y ( d B S

P L )

Channels

ChannelFreeTM


Benefits of Speed

Summary



• What you give with one hand you takewith the other:

– In other words, what you gain in sound

quality you lose with adjustment flexibility

Overlapping Channels -Drawbacks

Channels

ChannelFreeTM


Benefits of Speed

Summary



Multi-channels: The Report Card

• Today’s multi-channel amplification has overcomeproblems but has introduced compromises:

–Single channel sounded good but poor fitting flexibility

–Multi-channel fast had good fitting flexibility but sounded bad

–Multi-channel slow sounded better but issues of undershoot and overshoot introduced

–Multi-channel overlapping sounded better but issues of fitting flexibility introduced

Channels

ChannelFreeTM


Benefits of Speed

Summary



Multi-channels: The Report Card

M I X E D

Channels

ChannelFreeTM


Benefits of Speed

Summary







• Bernafon engineers looked at the mixedreport card of multichannel systems

• ... and they thought out of the box!

What is ChannelFreeTM?

• Instead of dividing the signal into many

channels...

Divided and recombined

sound path

Channels

ChannelFreeTM


Benefits of Speed

Summary



• They developed ChannelFreeTM: a uniquedigital signal processing strategy

What is ChannelFreeTM?

• Looks simple… but it offers the benefits of multi-channel amplification and more.........without compromises

Unbroken ChannelFree

sound path

Channels

ChannelFreeTM


Benefits of Speed

Summary



Channels

ChannelFreeTM


Benefits of Speed

Summary

ChannelFreeTM

No channels and extremely fast processing



• With ChannelFreeTM, speech is amplifiedin its entirety therefore the natural

structure is preserved• Research shows that spectralcharacteristics are most important for speech understanding

– Van Schijndel et al (2001)

– Boothroyd (1996)

Benefits of no channels

Maximum Speech Understanding

Channels

ChannelFreeTM


Benefits of Speed

Summary



ChannelFree

ChannelFreeTM = no spectral smearing



Amplified

with many

channel

system

Original

vowel /ee/

F1

F2

F3

40

50

60

70

90

80

Key

O u t p u t ( d B

S P L )

Frequency (Hz)500 350030002500200015001000 4000 4500 5000 5500 6000

Channels

ChannelFreeTM


Benefits of Speed

Summary



• All sounds processed without breakingsound into channels

• Natural characteristics of sound

maintained as with speech- e.g. timbre characteristics of music aremaintained


Clear, natural sound

Channels

ChannelFreeTM


Benefits of Speed

Summary



Channels

ChannelFreeTM


Benefits of Speed

Summary

ChannelFreeTM

Extremely fast processing



• Average speech carries ~10 phonemes per second

• ChannelFreeTM analyses and makes gainadjustments 16,000 times per second tocapture individual phonemes


Benefits of fast processing

Channels

ChannelFreeTM


Benefits of Speed

Summary



Using time domain processing, ChannelFreeTM:

1. Analyzes and make adjustments on everysample – Sampling rate is 16,000/second therefore

16,000 analyses and gainadjustments/second

– Instant response to the environment 1. Has a fast throughput time



Channels

ChannelFreeTM


Benefits of Speed

Summary



• Research shows that long throughput timecan interfere with sound quality, especiallyfor own voice

• Additional research shows that frequency-dependent throughput delay reducessound quality



Channels

ChannelFreeTM


Benefits of Speed

Summary



Proof

•Sound quality comparisons of 5 premium classinstruments for different input signals

Symbio, Diva, Claro, Canta 7 and Triano S

•Objective measurements were also made to seewhat correlates with subjective preference (low timedelay, low noise)

•Symbio got highest average rating by hearing

impaired subjects for male and female voice, andmusic*

•Symbio was significantly preferred for listening inquiet room (normal hearing)

Premium class sound quality:

NAL studyChannels

ChannelFreeTM


Benefits of Speed

Summary

* not statistically significant



Because:

• Symbio XT doesn't split sound into channels

• Symbio XT is extremely fast

• ChannelFreeTM is a radical departure from

traditional multi-channel amplification. It hasno compromises and therefore delivers:

ChannelFreeTM – The Report Card

Channels

ChannelFreeTM


Benefits of Speed

Summary

Maximum speech understanding




R E V O L U T I O N

ChannelFreeTM – The Report Card

Channels

ChannelFreeTM


Benefits of Speed

Summary



ChannelFreeTM SoundDemonstration



ChannelFreeTM





Next presenter:

Anna O’Brien

Topic: - OpenFit™

Documents

Audio Optica, Channel Free