Cisco Webex DX70 User Manual - Page 24

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Intelligent Proximity

On the Cisco Proximity Ultrasound Signal

Cisco video systems emit ultrasound as part of

the Proximity feature. Most people are exposed to

ultrasound more or less daily in many environments,

including industry, commercial applications and

home appliances.

Even if airborne ultrasound may cause subjective

effects for some individuals, it is very unlikely that any

effects will occur for sound pressure levels below

75 dB. Guidelines for ultrasound exposure limits vary

heavily between countries, but 75 dB is the lowest limit

presently found for the frequency band around 20 kHz,

which is where the Cisco proximity signal is emitted.

A good reference for this information is Health

Canada´s guidelines,

semt/pubs/radiation/safety-code_24-securite/

index-eng.php#a2.2.2.

These guidelines state that sound pressure levels

lower than 120 dB have not been demonstrated

to cause hearing losses, neither permanently nor

temporarily.

D1510422 User Guide

Cisco Webex DX70, DX80

Produced: September 2018 for CE9.5

For Cisco video systems for group use with

integrated loudspeakers the ultrasound sound

pressure level is below 75 dB at a distance of 50 cm

or more from the loudspeaker.

For Cisco video systems for personal use the

ultrasound sound pressure level is below 70 dB at a

distance of 20 cm or more from the loudspeaker.

For Cisco WebEx Boards the ultrasound sound

pressure level is below 75 dB at a distance of 20 cm

or more in front of the display. The level can be

slightly higher right below the display due to the

downward-facing loudspeakers.

In most practical cases the level at the ear of the

http://www.hc-sc.gc.ca/ewh-

user will be much lower than these max levels, due

to loudspeaker directivity, distance attenuation, and

high degree of high frequency absorption in typical

rooms. The levels will range from what for audible

sound would be typical background / ambient

noise levels in meeting spaces up to so-called

conversational levels of normal speech.

It is therefore deemed safe for humans to be

continously subjected to the proximity signal.

Most people will not be aware of the presence

of the signal, and suffer no effects from it. A few

individuals with especially acute high frequency

hearing can, however, be able to hear it, this is

most likely to happen directly in front of and close

to the loudspeaker.

It is obvious that animals like dogs will hear the

proximity signal, since their frequency range of

hearing is so much wider.

However, the effect of sound is also level

dependent, and the level range of a dog´s hearing

is not significantly different from that of a human.

The hearing threshold of dogs at 20 kHz can be as

low as 0–10 dB, similar to the threshold of a human

ear in its most sensitive frequency range.

Cisco has not done testing or qualification of the

possible effects the signal can have on dogs. Due

to the limited levels it is believed that while the

signal is clearly audible it is not bothersome to

dogs.

A dog in an office or meeting room will be subject

to ultrasound at levels comparable to normal

background noise, or at most conversational

levels. There has been no reports of animals being

bothered by the signals in the years we have had

this feature in our products.

However, the question of ultrasound effect on dogs

is fair, since dog repeller devices using ultrasound

do exist. These devices typically claim to use

discomforting, but not harmful ultrasound. Cisco

does not have insight into dog repeller design, but

scanning the specifications of such devices typically

reveals that the exposure levels typically are 100 dB

and upwards.

For solutions using Cisco video codecs with 3rd

party loudspeaker systems Cisco is not able to

control the ultrasound sound pressure level. In

most cases the necessary loudspeaker sensitivity

and frequency response will result in levels below

the 75 dB limit. However, if excessive external

amplification is applied, or the loudspeaker system

has an emphasized high-frequency response,

levels in excess of the limit can be produced.

About Proximity

The Intelligent Proximity feature allows

you to share content from a computer

wirelessly on the video system. Smart

phones and tablets are also able to

view the shared content directly on

their own screens.

You can even use your own smart

phone, tablets, PC or MAC to control

calls on the video system.

Observe the following:

You will need to download (free of

charge) the Cisco Intelligent Proximity

app from App Store or Google Play.

Windows or OS X users, go to

https://

proximity.cisco.com/.

Your video support team may have

activated none of the features, all of

them, or just a subset of them.

Intelligent Proximity makes use of

ultrasound when connecting users

(see more at left). Do not block the

microphone of your computer, smart

phone or tablet.

Intelligent Proximity has been designed

not to work outside the meeting room

when doors to the room are kept

closed. You will need to be in close

proximity of the video endpoint to use

the feature.

When privacy dictates, always keep the

meeting room entrance doors closed

to avoid possible eavesdropping from

adjacent rooms.