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 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• Loss of audibility of soft consonants

• Errors of undershoot and overshoot

Slow time constants - Drawbacks

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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Multi-channels: The Report Card

 M I X E D

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

ChannelFreeTM

No channels and extremely fast processing

8/2/2019 Audio Optica, Channel Free

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• 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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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ChannelFree

ChannelFreeTM = no spectral smearing

Benefits of no channels

Maximum Speech Understanding

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 no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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• All sounds processed without breakingsound into channels

• Natural characteristics of sound

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

Benefits of no channels

Clear, natural sound

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

ChannelFreeTM

Extremely fast processing

8/2/2019 Audio Optica, Channel Free

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• Average speech carries ~10 phonemes per second

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

Maximum Speech Understanding

Benefits of fast processing

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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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

Benefits of fast processing

Clear, natural sound

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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

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

Benefits of fast processing

Clear, natural sound

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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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 no Channels

Benefits of Speed 

Summary 

* not statistically significant

8/2/2019 Audio Optica, Channel Free

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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 no Channels

Benefits of Speed 

Summary 

Maximum speech understanding

Clear, natural sound

8/2/2019 Audio Optica, Channel Free

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 R E V O L U T I O N

ChannelFreeTM – The Report Card

Channels

ChannelFreeTM 

Benefits of no Channels

Benefits of Speed 

Summary 

8/2/2019 Audio Optica, Channel Free

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ChannelFreeTM SoundDemonstration

8/2/2019 Audio Optica, Channel Free

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ChannelFreeTM

8/2/2019 Audio Optica, Channel Free

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Next presenter:

Anna O’Brien

Topic: - OpenFit™