Distortion is more than harmonic distortion.

If any output does not replicate the input in amplitude and frequency response,
there is distortion ... period!

If a 1 Vp-p pure sine wave swept between 300 Hz and 3000 Hz goes into a device
and produces an output of 2 Vp-p pure sine wave between 300 Hz and 3000 Hz there
is a uniform gain of 2 and NO distortion.

If a 1 Vp-p pure sine wave swept between 300 Hz and 3000 Hz produces 2 Vp-p at
300 Hz, then rises to 2.5 Vp-p at 1000 Hz and further rises to 2.8 Vp-p at 3000
Hz, the signal is distorted! The output is NOT a constant multiplier of the input.

Run the test I posted. Or run it against a spectrum analyzer. Or, simply admit
the output does not replicate the input. Lack of replication, in amplitude,
frequency response or internal non-linearity, is distortion.

A-D is specifying harmonic distortion ONLY.

Speech compression is the deliberate introduction of distortion [to provide some
desired result]

In the recording industry, when analog recording was the norm, the recording
studio distorted the recorded signal by the addition of 'pre-emphasis'. That is
shaping the frequency response to compensate for known frequency variations in
the recording media. The playback electronics may have had 'de-emphasis',
depending upon recording media, to remove the effects of pre-emphasis and media
distortion so that the output replicated the input. That is controlled
distortion to achieve a desired result.

Speech compression in radio-telephony is intentional distortion to achieve a
perceived desired result.

In mathematical terms TD = THD + dA/dF + dA/dT + dA/dV + d(Af(F))/dF ... should
I continue?

TD = Total distortion
THD = Total Harmonic Distortion
dA/dF = Intentional Amplitude variation as a function of frequency
dA/dT = Amplitude variation as a function of temperature
dA/dV = Amplitude variation as a function of bias voltage [AKA common mode, bias
effects]
d(Af(F))/df = Amplitude and gain variations as a function of gain roll off of
the active device [a function of device gain rolloff [AKA gain*bandwidth product]].

I can add some more terms if you like.

As a Chief Engineer I know and understand exactly what I am stating.

A speech compression circuit deliberately produces a dA/dF, a variation in gain
as a function of frequency, to achieve an intended result. It is distortion!

As a company advertising and marketing a device, you should be precise in your
language or define your terms explicitly.

As far as I'm concerned this topic is dead, the funeral has been held, and the
grave has been covered. I have no need to defend myself.

Deek




Telstar Electronics wrote:

On Sep 19, 12:58 pm, Deek wrote:

I'm sure they will acknowledge that it introduces controlled distortion.


I'm surprised at you... being a chief engineer and all... you should
realize that in this audio application we're talking strictly about
harmonic distortion. After all, that's what you can hear. In the
Analog Devices datasheet (page2)... this is given for the SSM2166 as
"Total Harmonic Distortion including internal chip noise" of typical
0.25%... and a maximum of 0.5%. These figures rival the finest audio
equipment!
www.telstar-electronics.com