aparate auditive - channel free
TRANSCRIPT
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™