Thread Subject: Re: Volume Gain (2.2-E)

Note

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From: Diane Golden
Date: Tue, Sep 11 2007 12:05 PM

Correct me if I am wrong, but as I read 68.317 the FCC minimum requirement
for gain is only 12 dB without significant peak clipping. The 18 dB is a
gain maximum that can only be exceeded if the phone is equipped with the
automatic reset to default. So I'm not sure how many phones are actually
built to much beyond the 12 dB level . . .

Diane

-----Original Message-----
From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]
Sent: Tuesday, September 11, 2007 12:18 PM
To: = EMAIL ADDRESS REMOVED = ; 'TEITAC Committee'
Subject: RE: [teitac-committee] Volume Gain (2.2-E)


Thanks Diane,


Couple things.

1) Also include the "products typically held up to the ear" part. This
eliminates computers and other things including speaker phones.

2) We removed telecom from this language. Term is ambiguous now.

3) You said FCC as 12-18 in one place then 12 in another.
Did you meant to change 20 db limit down to 18?

Changing it from 20 db down to 18 db to match FCC would reduce perceived
loudness by only 15%.

If phones today do 18db but not 20 db. Can we move down to this?


(dropping from 20 db down to 12 db is a loss of volume of almost half (it
would be 43% lower perceived volume.)


20 db = 4x
12 db = 2.3x (43% less than 20 db)
18 db = 3.48x (13% less than 20 db)


CONCLUSION:
We could drop from 20 db to 18 db to meet FCC but 12 db would be a
significant drop- close to half.



Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.



> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED =
> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf
> Of Diane Golden
> Sent: Tuesday, September 11, 2007 11:59 AM
> To: TEITAC-Committee (E-mail)
> Subject: [teitac-committee] Volume Gain (2.2-E)
>
> Sorry for the length of this message, but I've attempted to
> summarize what I think are the issues/problems with the
> volume gain standard (currently 2.2-E part 3 in the Sept 3
> version). The current wording reads: "All other
> telecommunications products or systems that provide a
> function allowing voice communication must provide a gain
> adjustable from the normal unamplified level to at least 20
> dB above the normal unamplified level as measured in
> accordance with the provisions of the FCC regulation §68.317
> for volume control. The volume at the normal unamplified
> level setting must also meet the requirement in FCC
> regulation 68.317."
> 1) It appears that the intent of this volume gain standard
> (and the current
> one) was to require 20dB of built-in gain in every phone
> purchased. If it had meant compatibility with add-on AT
> (in-line amplifiers) or the ability to swap out hand sets
> with the required gain it should have read something like
> "Products shall have modular connectors to allow for the
> insertion of and/or compatibility with assistive technologies
> that provide at least 20 dB of volume gain without conflict
> with the FCC required built-in gain of 12 dB."
>
> 2) It appears that government agencies are unable to
> purchase phones with 20 dB of built-in volume gain as a
> feature of a ?standard phone? because such phone are not
> manufactured. When I posed the question about any purchases
> that did conform, the Access Board responded that they met
> the standard by adding on in-line amplifiers to all standard
> phones purchased.
> At a state level, I'm not aware of any agency who has
> purchased phones with built-in 20 dB of gain as a standard
> feature. I've not heard of any federal agency who has. So
> the only options seem to be purchasing add-on AT for every
> phone or purchasing all phones with a specially amplified
> handset that delivers the 20 dB gain. Both these options are
> really adding an external amplifier on to each and every
> product and it is unclear how compatible this is with the 12
> dB gain already built-in to every phone and how the reset to
> default requirement is met.
>
> 3) It appears that the built-in volume gain available on
> phones as a standard feature is the 12-18 set by the FCC.
> While the Section 508 standards attempted to set a higher
> level, it did not result in any products being manufactured
> to meet that higher level. As a result, agencies either
> bought the 12 dB level available and added-on AT or swapped
> out handsets only as needed by individuals -- or in a few
> cases (like the Access Board) an agency added-on AT to every
> phone purchased regardless of individual needs.
>
> 4) It appears two core questions need to be answered:
>
> A. Should the 508 standard continue to require 20 dB of
> built-in gain for every phone purchased? If so, then the
> standard should be re-written to clearly require that as
> there is obviously confusion about whether this is a built-in
> requirement for every phone versus it being OK to add-on as needed.
>
> B. Or should the 508 standard be revised to require 12 dB of
> built-in gain on all phones purchased (harmonize with the FCC
> requirements) and then require compatibility with add-on AT
> to reach gain levels of 20 dB or above?
>
> C. With either A or B, the standard should also address
> compatibility issues with add-on amplification (in the form
> of AT and/or a swapped out amplified handset) and the 12 dB
> gain that must be built-in per FCC requirements.
> Specifically, do the add-on?s ?double-up? amplification and
> what impact does that have on the distortion if delivered via
> a handset that cannot accommodate the doubled-up gain and
> if/how does the reset to default apply and work with the add-on?
>
> Diane Golden
> NASCIO
>
>

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