Next presenter: Cameron Martland

Topic: - ChannelFree™

1. To make important sounds audible and comfortable by providing:– frequency specific amplification– level specific amplification

2. Maximize speech understanding

3. 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 flexibility to fit varying dynamic ranges and non-linear targets

Single Channel

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• Multiple channels were developed that were finally able to achieve frequency and level-dependent amplification

• BUT these systems didn’t always sound so good

Multiple Channels

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• Why didn’t it sound so good?

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

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

Amplified with many channel system

Original vowel /ee/

F1

F2

F3

Multiple Channels

40

50

60

70

90

80

Key

Ou

tpu

t (d

B S

PL

)

Frequency (Hz)500 350030002500200015001000 4000 4500 5000 5500 6000

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• So the engineers thought again and found...

• It was possible to achieve less signal degradation via two mechanisms:

Multiple Channels

Slower time constants in each channel

Overlapping channels

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

slow

Number of channels

Spe

ed o

f c o

mpr

essi

on fast

low high

Equal sound quality

Slow time constants & multiple channels

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• 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

• Channels no longer act independently

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

Overlapping Channels

Frequency (Hz)

Inte

nsity

(dB

SP

L)

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• What you give with one hand you take with 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

Multi-channels: The Report Card

• Today’s multi-channel amplification has overcome problems 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

Multi-channels: The Report Card

MIXED

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• Bernafon engineers looked at the mixed report 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

• They developed ChannelFreeTM: a unique digital 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

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

ChannelFreeTM

No channels and extremely fast processing

• With ChannelFreeTM, speech is amplified in its entirety therefore the natural structure is preserved

• Research shows that spectral characteristics 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

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

Ou

tpu

t (d

B S

PL

)

Frequency (Hz)500 350030002500200015001000 4000 4500 5000 5500 6000

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• All sounds processed without breaking sound into channels

• Natural characteristics of sound maintained as with speech

- e.g. timbre characteristics of music are maintained

Benefits of no channelsClear, natural sound

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

ChannelFreeTM

Extremely fast processing

• Average speech carries ~10 phonemes per second

• ChannelFreeTM analyses and makes gain adjustments 16,000 times per second to capture individual phonemes

Maximum Speech Understanding

Benefits of fast processing

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

Using time domain processing, ChannelFreeTM:

1. Analyzes and make adjustments on every sample

– Sampling rate is 16,000/second therefore 16,000 analyses and gain adjustments/second

– Instant response to the environment

2. Has a fast throughput time

Benefits of fast processingClear, natural sound

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

• Research shows that long throughput time can interfere with sound quality, especially for own voice

• Additional research shows that frequency-dependent throughput delay reduces sound quality

Benefits of fast processingClear, natural sound

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

Proof

•Sound quality comparisons of 5 premium class instruments for different input signals

Symbio, Diva, Claro, Canta 7 and Triano S•Objective measurements were also made to see what correlates with subjective preference (low time delay, low noise)

•Symbio got highest average rating by hearing impaired subjects for male and female voice, and music*

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

Premium class sound quality: NAL study

Channels

ChannelFreeTM

Benefits of no Channels

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 has no compromises and therefore delivers:

ChannelFreeTM – The Report Card

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

Maximum speech understanding

Clear, natural sound

REVOLUTION

ChannelFreeTM – The Report Card

Channels

ChannelFreeTM

Benefits of no Channels

Benefits of Speed

Summary

ChannelFreeTM Sound Demonstration

ChannelFreeTM

Next presenter: Anna O’Brien

Topic: - OpenFit™