Re: Action item. definition and use of Clean audio in European television

On Tue, May 24, 2011 at 1:41 PM, David Singer <> wrote:
> On May 23, 2011, at 17:57 , Silvia Pfeiffer wrote:
>> On Tue, May 24, 2011 at 12:43 AM, David Singer <> wrote:
>>> On May 21, 2011, at 2:39 , Silvia Pfeiffer wrote:
>>>>> I don't think we should (a) stray from normal industry parlance or (b) assume that it's always the speech that is the main program content.
>>>> I agree. Since we are talking about a technology that diverges from
>>>> what the industry labels as "clean audio", we should therefore not use
>>>> the same term.
>>> Can you say how you think we are differing from the concept of 'clean audio'?  I agree that the way clean audio is achieved in various systems varies (quite widely) -- e.g. by isolating to a channel or two in some multi-channel environments, but I think we can achieve clean audio in HTML (and we should, and should at least conceive of the labeling for all sorts of conditions, such as high-contrast video).
>> Calling a video track that has high-contrast video "clean" is not
>> really appropriate either. I'd much prefer such a track to actually be
>> called "high-contrast" so its content makes sense.
> Agreed, I didn't mean to imply otherwise.
>> But back to audio.
>> I am mostly objecting to the term "clean audio" from the point of view
>> that most people understand something else as "clean audio" - just
>> search for the term and you will find that it refers to the quality of
>> an audio recording more than to the ETSI/BBC way of using it: it means
>> avoidance of clipping, interference, noise reduction, audio
>> restoration etc. To an audio person, a "clean audio" channel indicates
>> that this is a replacement recording to the main audio channel with a
>> higher-quality recording.
>> However, where ETSI/BBC and us use "clean audio", we refer to the
>> possibility of separately increasing the volume of the foreground
>> sound. And it ETSI's spec in particular it is reduced to adding a
>> speech-only channel. This is why I am suggesting the term "speech" to
>> be more appropriate.
> Ah.  I originally called this "high contrast" audio, as indeed the program material is highlighted against the background audio.  But it's not the industry term.
> I think "clean audio" means this, though: the program material (usually, but not always, speech) has been 'cleaned' of extraneous sound effects, background music etc.

Not quite when you look at those that talk about "clean audio" in the
way that we do. There, only "foreground dialogue and speech" is
explicitly mentioned, e.g. Note
that the overall effect of the presentation may be to receive "clean
audio" in the way that you describe, but the track's content is not
clean audio, but only "foreground dialogue and speech".

>> ETSI actually call a channel that contains speech-only for "clean
>> audio" purposes a "hearing impaired" channel. At least this describes
>> what the channel is being used for. "speech" would describe what it
>> contains. "clean audio" give a false indication of better sound
>> quality. I would be ok with "foreground sound", too, but I would be
>> very unhappy about the term "clean audio".
> How do you feel about 'contrast enhanced' or 'high contrast' or 'low distraction'?
> you say...I'd like to use industry terms even if, to our ear, they are not ... very clean. :-)

I think you believe that other sounds than speech and dialogue are
also enhanced/extracted for "clean audio". That is explicitly not the
case IIUC.


Received on Tuesday, 24 May 2011 04:40:07 UTC