# Re: About importance of "phase" in sound recognition

```It is my understanding that the response to a 'metric' question would be a number, or a formula, and the response to a psychometric question will be statistical. Regarding time delay, question one would be, "Is there time delay?". Question two would be, "Do you hear [the] time delay?"

My understanding is that the original question about phase was a psychometric question.

>> I've been confused about the role of "phase" information of the sound (eg speech) signal in speech recognition and more generally human's perception of audio signals.

It is also my understanding that there is a distinction between time delay caused by acoustics, and "phase" (shift) within the signal, from the source. I read that time delay would be characterized by the entire signal being "phase shifted", and internal (frequency region) phase shift would be characterized by some part(s) of the signal being 'out of phase'.

My next question may be arise depending on if I've got this right so far.

Kevin

On 2010, Oct 7, at 8:21 AM, Laszlo Toth wrote:

> On Thu, 7 Oct 2010, ita katz wrote:
>
>> I think that the distinction between signals which have or do not have phase
>> is not binary - it is a gradual transition between the two, since the
>> question 'when is a signal (semi) periodic?' does not have one answer, not
>> mathematically and not psychoanalytically - A sinosuid of .5 a period is
>> clearly not periodic, but a sinosuid of 100 periods clearly is - where is
>> the transition between the 'periodic' and 'non-periodic'? it is not a
>> point-transition.
>
> Matematically a function f is periodic if f(x)=f(x+p) for some p>0 for ALL
> values of x. So _mathematically_ your argument is clearly incorrect.
> It is another thing that I understand your argument and admit that it
> would make sense to have same more practical, "pschychoacoustic"
> definition of "periodic" and "phase". But my feeling is that such a
> definition does not exist, and this causes confusion.
>
>               Laszlo Toth
>        Hungarian Academy of Sciences         *
>  Research Group on Artificial Intelligence   *   "Failure only begins
>     e-mail: tothl@xxxxxxxxxxxxxxx            *    when you stop trying"
>     http://www.inf.u-szeged.hu/~tothl        *
```