directional microphone technology - Phonak

Peter Stelmacovich 

FM Classroom and February SF 2013 Product Manager

2 

• What are the options for improving Signal to Noise Ratio 

• Noise Reduction Algorithms? 

• Directional Microphone Technology 

• Remote Mic + ComPilot 

• Fixed gain FM (Digital and FM) 

• Adaptive Gain FM 

• Pros and Cons of each approach 

• Selecting Ideal Candidates 

FM Classroom February 2013

SNR in typical Listening situations 

• One-on-One 

• Television 

• Small groups 

• Place of Worship 

• Car 

• Concert/movie 

• Restaurant 

• Large group 

+10 dB 

+5 dB 

+3 dB 

0 dB 

0 dB 

+3 dB 

-5 dB 

-10 dB 




1) Directional hearing instruments 

2) Active noise reduction in hearing instruments 

3) Multiple programs 

4) Wireless transmission of the desired acoustic signal 

to the hearing instrument 

Almost always: binaural use of any technique shows better 

results than monaural use 


Pediatric_A_GB 

without dNC 

with dNC medium 

Time 

• Optimized algorithm for channel 

dependent noise detection and 

supression 

• 3 levels to control the degree of 

reduction - light, moderate or strong to 

addresses individual needs 

• Improves comfort and “ease of 

listening” in noisy surroundings 

• Helps concentration - crucial for 

learning 


• No documented empirical evidence 

demonstrating improved speech 

understanding in noise from hearing aid 

circuitry alone (Killion, 1997; Bentler, 2004; 

Ricketts 2004)) 

• Useful for Comfort but does not improve 

signal to noise ratio. Works well when used 

in combination with directional microphones 

(Plyler, 2007; Mueller et al 2006) 


• Improvements in SNR for directional microphone technology over 

omni directional microphones has been well documented. 

• Kochkin (Market Trak) use of directional microphone technology leads 

to increased performance and greater end user satisfaction. 

• Improved speech understanding (Valente et al, 1995; Gravel et al, 1999; 

Kuk et al, 1999; Preves et al, 1999; Pumford et al 2000; Rickets et al, 2000, 

2005; Cord, M, Surr, R, Walden, B, Olson, L., 2002; Bentler et al, 2006) 

• Documented range of improvement: 3-8 dB (Hawkins &Yacullo, 1984; 

Valente et al 1995; Gravel et al, 1999; Ricketts & Dhar, 1999; Pumford et al, 

2000, Valente et al, 2000). 


• Sound waves coming from in front 

are enhanced 

• Sound waves coming from the side 

or behind are reduced 

• Improved speech understanding in 

noise regardless of the direction of 

noise 

• Studies show substantial benefit for 

adults in noisy environments 

(Condie et al 2002, Gravel, Hanin 

et al 2004.) 



Directional Microphones 


13 

-35° 

0° 

35° 

- 60° 

60° 

-90° 

wider beam 

narrower beam 

90° 

-120° 

120° 

-150° 

180° 

150° 


14 

Less wind noise 

Wind noise detection 

Wind noise detection 

Streaming 

The signal is filtered and 

mixed by the receiving 

hearing instrument 


• Directional microphones have proven benefits (3-5 dB improvement in SNR) 

• BUT, microphone location is still at the ear level 

• Higher SNR‟s can be obtained by moving the microphone closer to the signal 

of interest


• By moving a microphone from 

the ear level to a much closer 

proximity to the talker‟s 

mouth, we can achieve higher 

signal-to-noise ratios 

• Phonak‟s solution involves the 

use of the Remote 

Microphone in conjunction 

with either a ComPilot or an 

iCom (backwards 

compatibility)

1. Improved SNR compared to ear level Directional Microphones 

2. Ease of Use. Simple and intuitive 

3. Convenient. ComPilot + Remote Mic gives client many solutions with just 

2 devices 

4. Cost. Very affordable solution, much less than FM

19 

• Wireless, omnidirectional microphone 

• Voice transmission directly to the HIs via ComPilot 

• Streaming up to 20 meters (60 ft) 

• Up to 8h streaming time 

• No audible delay 

• Lightweight 


• One-on-One conversations in noisy places 

• Listening to a speaker who is more than 2 meters away 

• Listening to a speaker who often changes position 

• When you cannot face the speaker (ie. in a car) 


• Wear it at the correct location 

– Clipped to a shirt 

• Max 20 meters (66 ft) is the official number 

• 20 cm from speaker‟s mouth in noise 

– Can be placed on a table in quiet situations 


Feature Phonak Dynamic FM Bluetooth Microphones 

Range 15m indoors. Up to 50 meters outdoors 15m (best case). Comfortable range is 8m 

SNR Up to 24 dB 12 dB 

Mic Selection Omni, Zoom, SuperZoom Omni only 

Connectivity 

Multiple receivers (ear level as well as 

inductive neck loop). Compatible with all 

brands of HI and CI. Audio input of all 

transmitters . Bluetooth on SmartLink+ 

Sends only to one receiver (body-worn 

streamer) 

Operating Time 10-12 hours 

5 hours 

Applications Single speaker, report style, conference Single speaker only

• To achieve an improvement in SNR up from a Bluetooth Microphone system 

would be to use a fixed gain wireless system 

• Examples include: 

– Phonak‟s 2 nd Generation systems such as Campus, SmartLink SX, 

ZoomLink, EasyLink (silver casing) 

– Oticon Amigo 

– Comfort Audio Digisystem 

• These are all examples of fixed gain systems and achieve similar results 

• Most incorporate directional microphones on the transmitters and therefore 

can achieve higher SNR‟s than Bluetooth microphones 

• Additional benefits include greater operating ranges and longer battery life 

• However, cost is significantly higher

• 48 adults, 2 sites 

• Presbycusis 

• Transmitter 3 inches from 

loudspeaker 

• Correlated HINT noise 

from 4 other loudspeakers 

• SuperZoom setting on 

HandyMic, Claro HI‟s. 

• 

Source: Valente 2002 


• Dynamic FM is different than fixed gain systems in that 

it adjusts the FM gain depending on the environmental 

noise level 

• Additional gain is added if the background noise level 

increases 

• Ambient noise levels are measured by the FM 

transmitter during speech pauses 

• If the ambient noise level rises to over 57 dB SPL, a 

command is sent from the transmitter to the Dynamic 

FM receivers to increase the FM Advantage 

• Examples: inspiro, SmartLink+, ZoomLink+, 

EasyLink+ and any 3 rd generation Phonak receiver (eg 

MLxi, ML9i to ML16i)

• The blue bar symbolizes the HI signal level 

• The FM level is usually louder 

• The difference is the SNR 

• Dynamic FM increases the FM level in noisy situations 

• Compression will reduce both the HI and the FM signal 

• The increased SNR is not affected by the compression in the 

hearing instrument 

SNR 

FM 

HI 

HI output 

signal levels 


• Ambient noise levels are estimated by the FM transmitter during speech 

pauses 

• If the ambient noise level rises to over 57 dB SPL, a command is sent from 

the transmitter to the Dynamic FM receivers to increase the FM Advantage 

• This command is a digital code, sent with the FM signal at a different 

inaudible audio frequency 

• If the noise level drops again, the FM Advantage is smoothed (reduced) 

appropriately. 


Dynamic FM gives 50% 

better word recognition than 

traditional FM in 73 dB(A) 

ambient noise! 

Reference: Benefits of Adaptive FM Systems on Speech Recognition in Noise for Listeners Who Use 

Hearing Aids. Linda Thibodeau. American Journal 36 of Audiology • Vol. 19 • 36–45 • June 2010 



• Candidacy: 

– Audiogram approach 

– LiSN-S/LiSN-S PGA 

– COSI 

• Factors to consider: 

– Dexterity 

– Technologically „Savy‟? 

– Ease of use 

– Listening situations 

– Cost 


1. Children with hearing loss that attend special (deaf) schools 

2. Children with hearing loss that attend regular schools 

3. Adult hearing instrument users 

4. Children and adults with cochlear implants 

5. Children and adults with unilateral hearing loss 

6. Children and adults with auditory processing disorder 

7. Non native learners (ESL) 

8. Adults with multiple sclerosis 

9. Children with Autism spectrum disorder 


• LiSN-S means Listening in Spatialized Noise – Sentences Under 

headphones a virtual 3D space is created with target sentences coming from 

the front and distracting sentences are coming from the left and the right. 

• It is like having a free field test under headphones with real life like conditions 

• The patient‟s task is to repeat sentences. 

• The distracting sentences are spoken by different voices than the target 

sentences, the condition is also called „Different voices ± 90º‟. 

• The professional enters the number of correct words. 

• LiSN-S is an adaptive test, the presentation level of the target sentences is 

adjusted automatically based on how many words were correct in the last 

sentence 

• The test ends automatically within 5 minutes. 

• LiSN-S has some unique features which will help fitters to justify their 

recommendations and which will convince patients of their hearing status and 

the required intervention 


• LiSN-S PGA is a brand new diagnostic test that measures speech 

understanding in noise in patients with a hearing loss. 

• PGA means Prescribed Gain Amplifier the stimuli are amplified according 

to the pure tone audiogram according to the NAL RP rule. 

• If there is a conductive component in the hearing loss, bone conduction 

thresholds are taken into account. 

• LiSN-S accurately measures a patients ability to understand speech in noise 

as if they were wearing hearing instruments (amplification), and by comparing 

a patient‟s performance on LiSN-S PGA with normative data stored in the 

software, LiSN-S PGA predicts accurately the patient‟s performance in noisy 

situations compared to normal hearing listeners of the same age, and if the 

predicted performance is not good, LiSN-S PGA gives clear, individual, 

technology recommendations how to improve speech understanding in noise. 

• So based on the responses by the patient to the sentences, the patient gets 

an evidence based recommendation. 


• Who should be tested with LiSN-S PGA? 

LiSN-S PGA has norms for age 6 to 60. Patients above 60 years old will be 

compared to the norms for 60 years old. The test is available in Australian 

English for Australia, New Zealand and UK and North American English for 

USA and Canada. 


Run the test 

Professional clicks „start‟ button 

competing sentences are played back. 

Professional clicks „next‟ button. 

Patient hears a beep and then 

the target sentence. 

Patient repeats the sentence. 

Professional enters the number of correctly 

repeated words 


• LiSN-S PGA is an adaptive test, which ends automatically. 


LiSN-S PGA‟s results mention clearly loss in signal-to-noise ratio (dB) 

The value (Loss in SNR) has been 

calculated by comparison with normative 

data for the average person of the same 

age with normal hearing. 

A cross (x) is displayed in the bar 

diagram indicating the individual 

score of the patient. 

Next to the x the technology 

recommendations are listed, in clear 

wordings for both the professional 

and the patient 


X 

With amplification the patient‟s loss of speech understanding in 

noise is very mild, and the patient should be able to understand 

speech almost as well as people with normal hearing. 


X 

Even with amplification, the patient will require speech to have a SNR 

significantly better than people with normal hearing in order to understand 

the speech. In many situations (where there is a close target talker or a 

close dominant noise source) advanced directional microphone 

technology will enable the patient to understand speech in noise almost 

as well as people with normal hearing. 


X 

Even with amplification, the patient will require speech to have a SNR 

significantly better than people with normal hearing in order to understand 

the speech. Bluetooth RemoteMic technology or fixed gain FM will 

enable the patient to understand speech in noise almost as well as people 

with normal hearing. 

Lower Yellow or Upper Red 


X 

FM Classroom February 2013 

Even with hearing aids incorporating advanced directional microphone 

technology the patient will require speech to have a SNR significantly better 

than people with normal hearing in order to understand the speech. In 

adverse listening conditions the patient is likely to be able to understand 

speech only with the aid of Dynamic FM technology coupled to the 

patient‟s hearing aids.

Peter Stelmacovich 

FM Classroom and February SF 2013 Product Manager

directional microphone technology - Phonak

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